FOOD Exam

Weight maintenance

- Maintaining weight loss long-term is more difficult than losing weight - Regular physical activity has been shown to help e.g. brisk walking for 60 mins/day - It is better to prevent weight gain in the first place

What are the health implications of consuming too much saturated fat?

Saturated fats up-regulate the production of cholesterol in the liver and decrease its removal from the body. High amounts of LDL-cholesterol are correlated with increased CHD rates and atherosclerosis.

What are the predominant sources of sodium in the general population?

Table salt and processed foods

What is the full name of the co-enzyme termed THF?

Tetrahydrofolate

The roles of the muscles of the oesophagus

The muscles that make up the oesophagus: - Contract the allow for the passage of food - Relax to allow the passage of food - Push the bolus of food down towards the stomach

Salts dissolve in the water (ions dissociate) and the water molecules cluster around them

The negative ions attract the positive part of the water (hydrogens) while the positive ions attract the negative part of the water (oxygen)

The disaccharide maltose is composed of which two simple sugars?

Two glucose

What is the composition of maltose?

Two glucose units

Adequate Intake (AI)

Used when an RDI cannot be determined. The average daily intake level based on observed or experimentally determined approximates of nutrient intake by a group that are assumed to be adequate

Estimating energy expenditure

Uses equations and an estimate of physical activity levels (PAL)

What is the full name of the co-enzyme termed NAD?

Nicotinamide adenine dinucleotide

If vitamin E is good for you, should we take a vitamin supplement 'just in case'?

No

Is haemophilia linked to vitamin K deficiency?

No

What compound supports good bacteria in the large intestine?

Non-digestible fibre

The 2013 Australian Dietary Guidelines

- "Summarise the evidence underlying food, diet and health relationships that improve public health outcomes" - "The guidelines, together with the underlying evidence base, provide guidance on foods, food groups and dietary patterns that protect against chronic disease and provide the nutrients required for optimal health and wellbeing" - To achieve and maintain a healthy weight, be physically active and choose amounts of nutritious food and drinks to meet your energy needs - Enjoy a wide variety of nutritious food from the five food groups every day and drink plenty of water - Limit intake of foods containing saturated fat, added salt, added sugars and alcohol - Encourage, support and promote breastfeeding - Care for your food, prepare and store it safely

Energy density of different foods

- 1 carrot = 72g - Energy content = 130kj - Energy density = 130/72 = 1.81 kj/g 1 serve of chips = 50g - Energy content = 698kj - Energy density = 698/50 = 14 kj/g

2017-2018 Australian overweight and obesity figures

- 1/4 children and adolescents where overweight or obese - 2/3 adults were overweight or obese - 1/3 of Australian adults were obese

Fatty acids and blood cholesterol levels

- 12:0, 14:0, 16:0 (saturated) and trans fatty acids increase plasma cholesterol levels - 18:1, 18:2 and 18:3 (mono and polyunsaturated) fatty acids decrease plasma cholesterol levels

Problems of overweight and obesity

- 2011-2012 over 2.3 million Australians (13%) over the age of 15 yrs reported being on a diet to lose weight or for another health reason - 15% of females - 11% of males - Few people succeed in losing weight - Even fewer lose weight permanently

Waist circumference

- >88cm is considered substantially increased risk for women - >102cm is considered substantially increased risk for men - Indicator of fat distribution and central obesity - Sometimes waist-to-hip ratio used, but waist circumference is easier

Vitamin B12 (Various cobalamins) Functions

- A cobalt containing organic molecule - Cyanocobalamin is a synthetic form of vitamin B12 found only in supplements while methylcobalamin (CH3-B12) is a naturally occurring form that you can get through either food sources or supplements - When cyanocobalamin enters your body, it's converted into either methylcobalamin or adenosylcobalamin, which are two active forms of vitamin B12 in humans - Works in conjunction with folate. The cobalamin removing a methyl group from the folate and in doing so activating both the folate and cobalamin - Vitamin B12 is indirectly necessary for DNA and RNA synthesis and cell multiplication as it converts the inactive methyl-THF to the active THF form of folate to support these functions - Vitamin B12 itself also maintains the myelin sheath around nerve fibres. Nerve cell damage results from B12 deficiency. Bone cell activity and metabolism are also B12 dependent - Vitamin B12 is only available from animal foods. It is made by bacteria in the GI tract of many animals, including us. But we cannot absorb this B12 as it is made in the lower part of the GI tract Folate and B12 often work as a pair and one doesn't work without the other

Correlations and causality

- A correlation occurs when the results of studies show a relationship between two factors - This is not evidence of causation! But an indication as to a possible association that needs to be investigated in the lab

Diet planning principles - Variety

- A diet can be adequate (it meets the NRVs), balanced (it meets all the NRVs, not just one or two), energy-appropriate, nutrient-dense and low in 'empty calories' but it could still be lacking in variety - E.g. the person may eat the same foods day after day - It is important to select foods from each of the food groups - AND - To vary which foods are selected from each food group - E.g. eat a 'rainbow' of fruit and vegetables

Healthy GI tract

- A healthy diet promotes a healthy GI tract and optimal nutrient absorption - Good sleep assists with the maintenance and repair of the GI tract - Physical activity promotes good GI muscle tone - Released mealtimes promote good regulatory hormonal control - In summary: balance, moderation, variety and adequacy should feature in everyday eating

Laterile - fictitiously called Vitamin B17 - vitamin imposter

- A number of compounds have been proposed by the nutraceuticals industry as well as social bloggers and convicted fraudsters as new vitamins with "scientific" evidence to support these claims - In some cases the vitamin compound can actually be dangerous (e.g. laetrile) - The US National Institutes of Health evaluated the evidence separately and concluded that clinical trials of laetrile showed little or no effect against cancer. The authors reported that "the hazards of the therapy were evidenced in several patients by symptoms of cyanide toxicity or by blood cyanide levels approaching the lethal range" - The study concluded "Patients exposed to this agent should be instructed about the danger of cyanide poisoning and their blood cyanide levels should be carefully monitored. It was concluded Laetrile is a toxic drug that is not effective as a cancer treatment" - Some North American cancer patients have travelled to Mexico for treatment with this substance. One of the patients was actor Steve McQueen, who died in Mexico following cancer treatment with laetrile and surgery

Iron deficiency

- A number of situations are linked to iron deficiency: - Poor vitamin C intake - Poor bioavailable intake (particularly vegans) - Blood losses from ulcers, GI parasites, blood donation, injuries, menstrual cycle - Iron deficiency symptoms: - Fatigue - Pale skin - Headaches - Cold hands and feet - Brusibng easily - Stages of iron deficiency - Iron stores depleted (ferritin) - Transport iron decreases (transferrin) - Haemoglobin production falls - Haemoglobin and haematocrit values measured in full blood examination (FBE) are late indicators of iron deficiency - Result of iron deficiency is anaemia (small (microcytic) pale (hypochromic) red blood cells) - Important to intervene early Anaemia: - Severe depletion of iron stores resulting in lowered haemoglobin stores - Formation of small, pale red blood cells incapable of carrying normal oxygen load from lungs to tissues - Faltering energy metabolism, followed by fatigue, weakness, headaches, apathy and pallor - Results in lack of motivation, apathy and restlessness

Ratios

- Another way to look at information regarding a person's diet for comparison between people and too standard recommended values is to use ratios - A comparison of 2 or 3 values where one is reduced to the value of one (often the lowest but not always). Often used to indicate the proportion of the different types of fat in the diet

Vitamin B3 (Niacin (nicotinic acid), Nicotinamide) Functions

- A single ring structure composed of C, H, O, N - Exists in two molecular forms: nicotinic acid and nicotinamide which are easily inter-converted - Niacin has two enzymes forms in the body: Nicotinamide adenine dinucleotide (NAD) and its phosphate form NADP - Both participate in many energy transfer reactions and carry Hydrogen and their high energy electrons from the TCA cycle to the ETC in a similar manner to riboflavin coenzymes - Some niacin can be made in the body from the amino acid tryptophan, through the conversion rate is poor (1:60), i.e. 1 mg niacin from 60 mg ingested tryptophan

How many times a year do we select what to eat (make food choices)?

- About 2200 times a year - If we assume a person makes 15 choices a day, it would mean that they make 5000+ decisions per year about what to eat

Energy out: the kilojoules the body expends

- About two-thirds of the energy a person expends/day = basal metabolism - Basal metabolic rate (BMR) is the rate that the body expends energy to maintain essential body function - E.g. breathing, heart beat, maintaining body temperature, filtering waste

Absorption of nutrients

- Absorption process varies depending on the type of nutrient and can be one of three types: - Simple diffusion - E.g. water and small lipids - Cross freely into the intestinal cells - Facilitated diffusion - E.g. water-soluble vitamins - These require a specific carrier to transport them from one side of the cell membrane to the other - Active transport - E.g. glucose and amino acids - These nutrients move against the concentration gradient which requires energy

Zinc-Iron interaction

- Absorption, transport and an excess or a deficiency of one can greatly impact on another - Iron and zinc bind to transferrin in the intestinal mucosal cells, for transport into the blood - A dietary ratio greater than 2:1 (iron:zinc) impairs zinc absorption - Conversely high zinc intake can impair iron absorption

Peristalsis

- Action that moves food along the GI tract and prevents food from going the wrong way - The majority of the GI is composed of two muscular layers; circular muscle (on the inside of the lumen) and longitudinal muscles (on the outside of the lumen) - Peristalsis occurs when the inner circular muscles contract and the tube tightens. When the outer longitudinal muscles contract the circular muscles tighten and so the tube is loose. As the circular and longitudinal muscles tighten and relax, the bolus moves ahead of the constriction

Vitamin K recommendations

- Adequate intake: - Men = 70 μg/day - Women = 60 μg/day - Vitamin K sources: - Bacterial synthesis in the digestive tract - Liver - Green, leafy vegetables and cabbage-type vegetables - People typically get 50% from bacterial synthesis and 50% from food - To improve absorption, it is best to eat vitamin K foods with some fat. So drizzle some olive oil or add diced avocado to your favourite leafy green salad

Vitamin A in the body

- After absorption via the lymphatic system, vitamin A is stored in the liver (in the form of retinyl esters which can be converted to retinol) - A special transport protein, retinol-binding protein transports vitamin A in the blood - The body can convert retinol to other active forms of vitamin A as needed - E.g. retinal (reversible) to participate in vision or retinoic acid (irreversible) to regulate growth

Factors affecting basal metabolic rate (BMR)

- Age - lean body mass diminishes with age, v BMR - Height - in tall, thin people, the BMR ^ - Growth - In children and pregnant women, the BMR ^ - Body composition (gender) - The more lean tissue, the ^ the BMR (males have a higher BMR than females). The more fat tissue, the v BMR - Fever - Fever ^ BMR - Stresses - Stresses ^ BMR - Environmental temperature - Both heat and cold ^ BMR - Fasting/starvation - Fasting v BMR (loss of lean body tissue) - Malnutrition - malnutrition v BMR - Hormones (gender) - The thyroid hormone thryroxine, e.g. can speed up or slow down the BMR. Premenstral hormones slightly raise the BMR - Smoking - Nicotine ^ energy expenditure - Caffeine - ^ energy expenditure - Sleep - BMR is lowest when sleeping - Physical activity - Physical activity ^ BMR - Gender - men generally have a higher BMR - Growth - BMR is high in people who are growing - Age - BMR declines as lean body mass decrease - Physical activity - Activities are clustered by intensity and vary considerably - Body composition and body size - BMR is higher in people with lots of body mass than in those with less

The special case of alcohol

- Alcohol (drinking) = ethyl alcohol (ethanol) - There are potential health benefits to consuming low amounts of alcohol, but alcohol is a poison and moderate-high intake leads to many health problems - Alcohol behaves like a drug, altering many body functions, including brain activity, leading to high risk and dangerous behaviour - Alcohol in the body is quickly absorbed (mostly directly from the stomach) - Carbohydrate foods may slow the absorption of alcohol to a small extent - Alcohol abuse can cause fatty liver and is the first stage of liver deterioration - Fibrosis is the second stage - Cirrhosis is the most advanced stage of liver deterioration

What are the long-term consequences of excessive alcohol consumption on someone's vitamin status?

- Alcohol-induced thiamine (vit B1) deficiency - Alcohol displaces food from the diet and lowers thiamine intake and increases urinary excretion of thiamine - Alcohol-induced pyridoxine (vit B6) deficiency - Acetaldehyde (metabolised from alcohol) separates the PLP coenzyme (vit B6 is a big part of PLP coenzyme) from its enzyme → PLP coenzyme excreted → pyridoxine (vit B6) deficiency - Alcohol-induced folate (vit B9) deficiency - High alcohol intake initiates GIT injury → folate deficiency → decreased absorption of other nutrients too - Niacin (NAD) deficiency

Who do the ADG apply to?

- All healthy Australians - People of all ages and backgrounds in the general healthy population, including people with common diet-related risk factors such as being overweight - They do not apply to: - People with medical conditions requiring specialised dietary advice - Frail elderly people at risk of malnutrition

Alternative sweeteners

- All of the sweeteners have been tested and deemed safe for use by Food Standards Australia New Zealand (FSANZ) - There are three groups of alternative sweeteners, which all have different effects on blood glucose levels and weight - Artificial sweeteners - these are also known as 'non-nutritive sweeteners' because they provide no energy and no carbohydrate. e.g. aspartame, sucralose - Herbal products - e.g. stevia. A herbal product that provide no energy or carbohydrates - Sugar alcohols - these are also known as 'natural sweeteners' because they still provide kilojoules. They will evoke a blood sugar response. E.g. Isomalt, mannitol, sorbitol

Metabolic processes: Enzymes

- All reaction steps in any metabolism process require enzymes - Enzymes are protein molecules that facilitate rapid chemical reactions without being changed themselves and are able to be used over and over again actin as catalysts - Each enzyme requires a coenzyme, a small organic molecule that binds to and assists the enzyme - Some reactions in energy metabolism are coupled reactions. Energy released from breakdown of one compound is used to create a bond in a new compound - However the energy released from macronutrient breakdown has to be captured in ATP molecules first, then transferred to another reaction

Metabolism of Alcohol

- Although alcohol contains available energy (29kj/g), its metabolism is handled differently in the body, compared with the three macronutrients - Alcohol metabolism interferes with the metabolism of the other macronutrients and impairs health and nutrition Impairs absorption of vitamins and minerals - Although alcohol contains energy (29kj/g), the energy it releases is largely converted to fat in the liver - It also causes energy from the macronutrients to be converted to fat due to its high demand for NAD molecules, thus fewer available for the normal TCA cycle function - If NAD is insufficient for TCA cycle activity, the macronutrient molecules being broken down to acetyl-CoA have to be converted to fat - As the coenzyme NAD is based on the niacin molecule, people with high alcohol intake have a higher demand for niacin in their diet - High alcohol intake has been observed to cause Wernicke-Korsakoff syndrome, through severe thiamine deficiency due to alcohols interference with thiamine uptake by the GI tract. Hence high alcohol intake also results in a higher demand for thiamine in the diet - Thiamine forms a critical coenzyme (thiamine pyrophosphate (TPP)) involved in glucose metabolism and in the TCA cycle

Protein turnover

- Amino acid pool is made of degraded proteins and those from dietary protein intake - Amino acids can be used to make new proteins, other biological molecules containing Nitrogen (i.e. DNA) or as an energy source - In a healthy adult, when protein degradation = protein synthesis, 'Nitrogen balance' - Positive nitrogen balance occurs when people take in more protein (nitrogen) than being excreted: Nin > Nout - E.g. childhood, pregnancy and recovery from illness - Negative nitrogen balance when people lose more protein (nitrogen) than being consumed: Nin < Nout - E.g. occurs in illness, starvation, excessive training

Measuring protein quality

- Amino acid scoring - This is the ratio of a gram of the limiting amino acid in a test food to the same amount of the corresponding amino acid in a reference protein (e.g. whole-egg protein) multiplied by 100. Scoring is based on the limiting amino acid (the one that falls shorted compared to egg) - Biological value (BV) - A measure of the proportion of retained protein from a food (that which gets incorporated into the proteins of the body) to the amount of protein that is absorbed. It summarises how readily the broken down protein can be used in protein synthesis in the cells of the organism - Proteins from animal sources generally have a higher BV than proteins from plant sources because the pattern of amino acids in animal cells is comparable to the pattern in human cells - Net protein utilisation - The net protein utilisation, or NPU, is the ratio of amino acid converted to proteins (retained) to that which is supplied (consumed) - Protein Efficiency Ratio - Protein efficiency ratio (PER) is based on the weight gain of a test subject divided by its intake of a particular food protein during the test period - Protein Digestibility Corrected Amino Acid Score (PDCAAS) - A method of evaluating the protein quality based on both the amino acid requirements of human and their ability to digest them. The amino acid score is multiplied by the food's protein digestibility percentage to determine PDCAAS

Glucogenic vs ketogenic amino acids

- Amino acids are either glucogenic or ketogenic - They enter the energy metabolism pathway at different points - Which amino acids are glucogenic versus ketogenic is a complex and confusing area - Generally any amino acids that can be converted to glucose is glucogenic - Those that enter the metabolic pathway via pyruvate in the cytoplasm are clearly glucogenic as they can undergo gluconeogenesis to form glucose - Some others that enter as acetyl-CoA or a TCA cycle intermediary can also form glucose by other pathways. If they cannot they are termed ketogenic

Diet planning principles - Adequacy

- An adequate diet provides sufficient energy and enough of all of the essential nutrients to meet requirements - E.g. for iron: - The body loses some iron each day - If this is not replaced via the diet, over time, symptoms of iron-deficiency may develop - E.g. person may feel weak, tired and listless (lacking energy or enthusiasm) - To prevent this occurring, a person needs to consume adequate amounts of iron - This is the same for all other essential nutrients

Vitamin E recommendations

- An adequate intake (rather than EAR/RDI) was set for vitamin E based on median intakes of healthy populations in Australia and New Zealand - Adequate intake: - 10 mg/day for men aged 19+ - 7 mg/day for women aged 19+ - Upper level = 300 mg/day for adults aged 19+

Iron (Fe, Fe3+, Fe2+)

- An essential nutrient that is dangerous at high intakes - Second most significant nutrient deficiency in the world and the most prevalent in western society - Iron exists in 2 interchangeable ionic states in food and the human body: Fe2+ (Ferrous) and Fe3+ (Ferric) - Iron is a cofactor to enzymes involved in oxidation reduction reactions - Involved in cellular energy production, in the TCA cycle, attached to some enzymes and in electron carrier proteins for the electron transport chain (ETC) - Approx. 2.4g iron in the human body - Although these above functions are critical, they use only a small amount of iron - Most of the bodies iron is found in 2 particular proteins where it is involved in oxygen transport and storage (haemoglobin and myoglobin) - Iron is conserved in the body, most is recycled from one form to another with only minor losses - Losses must be replaced via absorption from food

Where is stearic acid commonly found?

- Animal fat - Cocoa butter (chocolate)

Fatty acid composition of different fats and oils

- Animal fats and the tropical oils of coconut and palm are mostly saturated fatty acids - Coconut oil - Butter - Beef tallow - Palm oil - Lard - Some vegetable oils, such as olive and canola are rich in monounsaturated fatty acids - Olive oil - Canola oil - Peanut oil - Many vegetable oils are rich in polyunsaturated fatty acids - Safflower oil - Flaxseed oil - Walnut oil - Sunflower oil - Corn oil - Soybean oil - Cottonseed oil

Effects of milling and processing on vitamin content of grains

- Decreases thiamine (B1), niacin (B3) and pyridoxine (B6) contents - Germ (outer layer) of the grain has high contents of vitamins - removing this decreases the vitamin content

Vitamin E summary

- Antioxidant (stabilisation of cell membrane, regulation of oxidation reactions, protection of polyunsaturated fatty acids (PUFA) and vitamin A) - Deficiency symptoms Erythrocyte haemolysis, nerve damage - Toxicity symptoms = Haemorrhagic effects - Significant sources = vegetable oils, nuts and seeds

Phospholipids in foods

- Apart from their presence in cell membranes, phospholipids are used in the food industry to suspend lipids in an aqueous environment (emulsifiers) - This property is due to the fact that phospholipids have a non-polar (lipophilic) region (the two fatty acid) and a polar (hydrophilic) region (the phosphate/base group)

Drivers of food intake - Appetite and Hunger

- Appetite - Prompts a person to eat - or to not eat - Hunger - Irritating feeling - prompts thoughts of food - Motivates us to eat - Is controlled by chemical messengers in the brain, particularly the hypothalamus - Influenced by presence or absence of nutrients in the bloodstream, size and composition of the previous meal, customary eating patterns, climate (heat reduces eating, cold increases), exercise, hormones and physical and mental illness - Stomach acts as a hopper - around 4 hours after a meal, all the food has left the stomach

Body shape and risk of chronic diseases

- Apple - Higher risk of heart disease, diabetes, cancer and high blood pressure - Not normal - More common in men - Causes lower-back pain - Shape can be changed. Fat stores around the middle respond well to low-fat eating and exercise - Pear - No health risk (only a fashion risk) - Normal - More common in women - Doesn't cause back pain - Shape is difficult to change. Low-fat eating and exercise will produce a smaller pear

Calcium absorption

- Approx. 20-30% of ingested calcium is absorbed, remainder passes through the GI tract bound to other substances - Acidity keeps calcium in a soluble form. Best absorbed with meals due to secretion of stomach acid generated by foods - Vitamin D, milk lactose and dietary phosphorous aid calcium absorption - Degree of absorption is regulated by production of calcium binding protein (CBP - Vitamin D affected) required to bind calcium in the GI tract mucosal cells and subsequent transport into the blood - Absorption is higher in children and pregnant women (50-60% absorption) - Absorption is hindered by high levels of: fibre, phytates (grains) and oxalates (vegetables) and high protein intakes Food sources: - broccoli, milk, plain yoghurt, cheddar cheese, tofu, sardines with bones, bok choy

Small intestine - structure

- Approximately 3-4 metres long with a diameter of 2-3cm - Layers of the small intestine from inside = Mucosa (protective layer), Lumen, Circular muscle layer, Longitudinal muscle layer, Serosa - The lumen's surface has folds and ridges which increase the SA and are called the valves of Kerckring - The valves of Kerckring have villi which further increase the SA - Villi have microvilli which further increase the SA - The microvilli provide the large absorptive surface (equivalent to a tennis court in area) - Any nutrient molecule small enough to be absorbed will become trapped among the microvilli in crypts - The large surface area allow nutrients to enter mucosal cells and pass into the blood stream or lymphatic vessels (lacteals)

Amount of minerals in a 60kg human body

- Arbitrary choice of definition of major minerals (i.e. 5g level in the body) - In retrospect a better cut off may have been 2g

Vitamin B2 (Riboflavin) Deficiency

- Ariboflavinosis: which may result in: - Cheilosis (cracks in the lips), - High sensitivity to sunlight, - Angular cheilitis (cracks and redness at corners of mouth), - Glossitis (inflammation of the tongue), - Painful, smooth, purple tongue - Seborrheic dermatitis (general skin inflammation with greasy scales), - Pharyngitis (sore throat), etc. - Inflamed eyelids

Health risks of obesity

- Arthritis - Asthma - Cancer - Back problems - Mental and behavioural problems - Hypertension - Chronic obstructive pulmonary disease - Diabetes - Heart, stroke and vascular disease - Kidney disease

Vegetarian diet planning

- As with any type of diet - there are examples of the good, the bad and ugly - Just because it is vegetarian/plant-based/vegan doesn't mean its healthy - Use Australian Guide to Healthy Eating recommendations and select foods from all fibre healthy food groups

Zinc losses

- As with iron, the body constantly loses zinc - Skin and hair contribute to loss, as well as seminal fluid in males

Fluid and electrolyte balance

- As with water, the amount of electrolytes in the body must remain constant. This involves a balance between intake and excretion - It is controlled by the excretory side of the process by the GI tract and the kidneys - Excretion via the sweat glands is an obligatory loss that is not controlled - Cell membrane transport - Transport proteins (cell membrane) regulate positive ion movement into and out of cells, negative ions then follow positive ions by attraction and water then flows toward the more concentrated side of the membrane by osmosis - The sodium potassium pump is an example of a membrane transport protein

Vitamin C toxicity

- At levels of 100 mg/day, tissues are saturated with Vitamin C - Some people take vitamin C at levels 20-40 times greater than the RDI. At this level the vitamin acts more like a drug than a vitamin and may take on many unknown functions - The majority of the excess above bodily vitamin needs however are quickly excreted in the urine - Excess intake (>1-2 gams/day) can lead to: - Nausea, - Diarrhoea and - Abdominal cramps - Can interfere with anticoagulants such as warfarin and heparin although the method is unclear - In metabolic abnormalities can form kidney stones if intake is high - High vitamin C intake can lead to increased iron absorption and release from body tissue leading to iron overload in the blood - High vitamin C intake and excretion can give false positive urinary diabetes tests as vitamin C can be falsely identified as glucose due to their similar structure - The body adapts to high vitamin C intake by upregulating efficiency of excretion - A sudden drop in intake to normal RDI levels may cause a deficiency (withdrawal reaction) as the body is still excreting large amounts and take time to adjust

Deficiency and toxicity of trace minerals

- Each trace mineral has a range of deficiency symptoms, some are severe, others are mild and difficult to identify - Main effect of deficiency is poor growth in children - Most are toxic even slightly above the recommended intake - Excessive intake is unlikely from food but is possible from supplementation - Trace minerals interact with each other: An excess or deficiency of one trace mineral can cause problems with other minerals

Digestion and absorption of lipids

- Average western diet contains approximately: - 50-100g triglycerides per day, - 4-8g of phospholipids per day and - 300-450mg cholesterol/plant sterols per day - Lipids do not mix well in the aqueous environment of the GI tract where lipase enzymes are located - A number of digestive processes are therefore required for lipid breakdown and absorption - Digestion of triglycerides by lipase enzymes in the first section of the small intestine usually leads to a monoglyceride and two fatty acids - Before this chemical reaction can take place the physical reaction of separating the particles of fat into small particles via bile needs to occur

B group vitamins in energy metabolism

- B group vitamins form a range of coenzymes that are involved in all metabolic processes - They are particularly relevant to the energy metabolism system that releases the energy from macronutrients at almost every stage in the processes of glycolysis, TCA cycle and ETC - In most cases, the vitamin is a small but essential part of the coenzyme structure as in: - NAD and NADP (niacin B3) - Nicotinamide adenine dinucleotide and nicotinamide adenine diphosphate) - FMN and FAD (riboflavin B2) - Flavin mononucleotide and flavin adenine dinucleotide - TPP (thiamin B1) - Thiamin pyrophosphate - THF (folate B9) - Tetrahydrofolate - PLP (B6) - Pyridoxal phosphate - CoA (Pantothenic acid B5) - Coenzyme A - Biotin and Vitamin B12 tend to act as coenzymes in the unchanged molecular form

Metabolic processes: Enzymes and coenzymes

- B group vitamins form coenzymes to assist enzymes in metabolic processes - The coenzyme is usually made up of a B group vitamin with other chemical components attached - The coenzyme complex now fits neatly into the much larger protein enzyme molecule making it active - The entire unit is now ready to catalyse a chemical reaction, either catabolic or anabolic. Once the reaction occurs, the enzyme-coenzyme unit is reused many times over

Fit and fat versus sedentary and slim

- BMI and weight gains do not tell us the whole story - Cardio fitness is a major key in health and longevity - Overweight but fit people may have lower risks than normal-weight unfit people - But this is an area of scientific research and debate

What are BMIs limitations?

- BMI does not reflect body composition - Not relevant to all population groups (ethnicities, not consider muscle mass) - Does not indicate distribution fats in the body

Diet planning principles - Balance

- Balance involves consuming enough - but not too much - of each type of food - For example: - Meat and eggs are a good source of iron but low in calcium - Dairy foods are a good source of calcium but are low in iron - There needs to be room in the diet for both sources of iron and sources of calcium, plus other foods that supply the other nutrients we need

What are the qualifiers for something to be a vitamin?

- Be essential for life - Not be manufactured in the body (in sufficient amounts)

Behaviour and attitude to promote weight loss

- Behaviour modification - how to change behaviour to increase energy expenditure and decrease energy intake - Awareness of behaviour is the first key - Changing behaviours one at a time works best - Do not grocery-shop when hungry - Eat slowly - Exercise while watching television - Cognitive restructuring can replace negative thoughts - Frequent self-monitoring is required - Support groups can be helpful in making changes

Physical activity to promote weight loss

- Being active boosts the metabolism for up to several houses after excising - Active people have a lower percentage of body fat - Exercise may curb appetite - Include exercise as part of a weight-control program as it can: - Increase energy expenditure - Help to control appetite - Reduce stress (and stress-related eating) - Enhance physical and psychological wellbeing

Vitamin B9 (Folate) Food sources

- Best sources are liver, legumes and vegetable and folate fortified foods. Dairy products are a poor source and folate is destroyed easily by cooking - Broccoli, Tomato juice, Pinto beans, Lentils, Asparagus - Folate is the most vulnerable B group vitamin in terms of interactions with drugs, leading to deficiency - In Australia, from 13 Sept 2009, mandatory folic acid fortification began requiring the addition of folic acid to all wheat flour for bread making, with the exception of organic bread - Decreasing spina bifida cases in USA since folate fortification of foods began in 1996

Vitamin B7 (Biotin) Functions

- Biotin has an unusual ring structure containing C, H, O, N, S attached to a short chain fatty acid - Forms a coenzyme that is involved in several important metabolic pathways - The most critical function of biotin in energy metabolism is in facilitating the reaction of CO2 with pyruvate (3C) to yield oxaloacetate (4C) (critical for TCA cycle continuity) - Pyruvate + CO2 ---(biotin)---> Oxaloacetate - A coenzyme for carboxylase enzymes, needed for synthesis of fatty acids and in gluconeogenesis

Blood glucose homeostasis

- Blood glucose concentrations should be between 4-10 millimoles/litre 1. When a person eats, blood glucose levels rise 2. High blood glucose levels stimulate the pancreas to release insulin into the bloodstream 3. Insulin stimulates the update of glucose into cells and storage as glycogen in the liver and muscles. Insulin also stimulates the conversion of excess glucose into fat for storage 4. As the body's cells use glucose, blood levels decline 5. Low blood glucose stimulates the pancreas to release glucagon into the bloodstream 6. Glucagon stimulates liver cells to break down glycogen and release glucose into the blood 7. Blood glucose levels begin to rise

The glycaemic response

- Blood glucose levels rise after digestion of carbohydrate - Foods that cause a rapid and large rise in blood glucose are called high glycaemic index (GI) foods - E.g. white bread, potatoes, rice, sugary foods and drinks - Low GI foods result in a slower, more gradual rise in blood glucose following a meal and do not reach the same high blood glucose concentration - Carbohydrates found in wholegrain product and those combined with fat and fibre tend to have a lower GI

12 requirements of a food label in Australia

- Food identification - Percentage labelling (e.g. contains 6% strawberries) - Nutritional information panel - Information for people with food allergies/intolerances - Date marking - Ingredient list - Labels must tell the truth - Food additives - Directions for use and storage - Legibility requirements - Country of origin - Nutrition and health claims

Blood volume and pressure

- Blood volume correlates with blood pressure (BP) - Blood volume and pressure are controlled by several mechanisms: - Antidiuretic hormone (ADH) - ADH is released from the pituitary gland in response to concentrated blood (low blood volume or low BP) - ADH stimulates kidneys to reabsorb more water from that which it has just filtered into urine and decrease excretion of urine - Renin-angiotensin system - Juxtaglomerular apparatus of the kidney nephrons detect low BP and release the enzyme renin in to the circulatory system. Renin then: - Activates the angiotensin(ogen) hormone (produced in the liver) to cause vascular constriction - Angiotensin then induces aldosterone release from adrenal glands, that cause the kidneys to reabsorb sodium (and hence water is reabsorbed by osmosis)

Iron overload

- Body normally absorbs less iron when body stores are full - Haemochromatosis, a genetic defect can lead to iron overload - Due to dietary supplements, blood transfusions and rare metabolic disorders - In hemosiderosis, large deposits of the protein haemosiderin storing excess iron occurs - Symptoms include: fatigue, headaches, irritability, enlarged liver, lethargy, skin pigmentation, joint disease, body hair loss - Condition is exacerbated by alcohol consumption - Iron overload can increase the risk of diabetes, heart disease, liver cancer

Storage of excess energy as fat

- Both the glucogenic and ketogenic amino acids can be converted to storage fat if eaten in excess of bodily protein and energy needs - Pyruvate from glucogenic amino acids can be converted to acetyl-CoA and used to make fatty acids in the same way that acetyl-CoA from ketogenic amino acids are used to produce fatty acids - Fatty acids are then linked to glycerol to produce triglycerides for storage. Thus high protein diets can build fat as well as muscle - Similarly excess carbohydrate and fat itself can be converted to storage body fat

Fatty acids in the diet

- Both triglycerides (TG) and phospholipids (PL) contain fatty acids - Each TG has 3 fatty acids that may be a mixture of chain lengths and double bond numbers - Each fat or oil contains a mixture of many different TG molecules with various combinations - If the fat or oil has a majority of PUFAs overall, it is termed a polyunsaturated lipid (but it will still have some saturated and monounsaturated fatty acids) - If the fat or oil has a majority of MUFAs overall, it is termed a monounsaturated lipid (but it will still have some saturated and polyunsaturated fatty acids)

From guidelines to shopping trolley

- Breads and cereals: - Refined products may have lost many nutrients - Enriched products may have had vitamins and minerals added - Wholegrain products are high in fibre and support good health and should comprise the majority of bread and cereal choices - Vegetables: - Can be fresh, frozen or canned - Aim to choose those without added fat or salt - Good sources of vitamins and minerals - Legumes are also a great low-fat, high-fibre option - Meat, fish and poultry: - Provide essential minerals e.g. iron - 120g raw meat = ~100g cooked meat - Try cooking without adding fat - Trim visible fat or buy lean cuts - Milk: - Low-fat milk contains approx. 1.5% or 1.5g/100mls of fat - Milk can be fortified (e.g. with vitamins A and D) - Non-dairy alternatives need to be calcium fortified (at least 100mg/100ml)

During periods of feasting, how are metabolic fuels used differently compared to their use with a healthy, consistent diet?

- Carbohydrate -> glucose -> glycogen stores + body fat stores - Fat -> fatty acids -> body fat stores - Protein -> amino acids -> body proteins + body fat stores

Digestion within the mouth: chewing and swallowing, with little digestion

- Carbohydrate digestion begins as the salivary enzymes start to break down the starch from bread and peanut butter - Digestive fibre covering on the sesame seeds is crushed by the teeth which exposes the nutrients inside the seeds to digestive enzymes - Fat digestion is minimal. Some hard fats begin to melt as they reach body temp - Protein foods are moistened by saliva

Digestion within the stomach: collecting and churning, with some digestion

- Carbohydrate digestion continues until the mashed sandwich has been mixed with the gastric juices; the stomach acid of the gastric juices inactivates the salivary enzymes and carbohydrate digestion ceases - Proteins from the bread, seeds and peanut butter begin to uncoil when they mix with the gastric acid making them available to the gastric protease enzymes that begin to digest proteins - Fat from the peanut butter and seeds forms a separate layer on top of the watery mixture

Digestion within the small intestine: digesting and absorbing

- Carbohydrate digestion picks up when the pancreas sends pancreatic enzymes to the small intestine via the pancreatic duct to break down starch. Enzymes of the surface of the small intestine cells complete the process of breaking down starch into small fragments that can be absorbed through the intestinal cell walls and into the hepatic portal vein. Sugars from the banana require so little digestion that they begin to traverse the intestinal cells immediately on contact - Fat from the peanut butter and seeds is emulsified with the watery digestive fluids by bile. Now the pancreatic and intestinal lipases can begin to break down the fat into smaller fragments so that they can be absorbed through the cells of the small intestinal wall and into the lymph - Protein digestion depends on the pancreatic and intestinal processes. Small fragments of protein are liberated and absorbed through the cells of the small intestinal wall and into the hepatic portal vein - Vitamins and minerals are absorbed

Energy-yielding nutrients

- Carbohydrates - Contain C, H, O - 17 kj energy/gram - Sugars/starches/some fibre (non-energy) - Lipids (fats and oils) - Contain C, H, O - 37 kj energy/gram - Several classes (TG, PL, sterols etc.) - Protein - Contain C, H, O, N (S) - 17 kj energy/gram - Made up of amino acids

The chemistry of carbohydrates

- Carbohydrates are made up of C, O, H - Carbon forms 4 bonds - Oxygen forms 2 bonds - Hydrogen forms 1 bond - Hydrates of carbon - The molecular formula takes the form (CH2O)n (a 'hydrate of carbon) - C:H:O = 1:2:1 - Monosaccharides = mono (one) + saccharide (sugar) - The three simple sugars important to nutrition are; fructose, glucose and galactose - Fructose, glucose and galactose have different structures but the same molecular formula - CH12O6

Function of carbohydrates

- Carbohydrates provide fuel for the central nervous system and the working muscles - Glucose is the primary energy substrate in the brain. The functional blood-brain barrier allows glucose to cross, but does not permit the passage of other pathogens or solutes in the body - Glycogen (the storage form of carbohydrates) provides about half of the energy that muscle and the body tissues use - Carbohydrates also prevent protein from being used as an energy source

The 2013 Australian Dietary Guidelines - Guideline 5

- Care for your food, prepare and store it safely - If buying packaged food, check its best-before or use-by date - Use an esky, insulated bad or box with an ice pack if you need to travel more than half an hour home or if it's hot outside. Store your food at home as soon as you can - Chill foods in the fridge to slow growth of micro-organisms. Keep cool foods cool and frozen foods frozen - Keep fridges at or below 5ºC and the freezer between -15 - -18ºC - Keep your fridge and freezers clean and get rid of those old shrivelled vegetables, left-overs or frozen foods lurking in the corners for too long - Store foods away from cleaning agents and insecticides - If you are not going to eat cooked dishes and foods straight away, put them in the fridge as soon as you can

Protein - Transport

- Carrier proteins in blood for transporting lipids, fat soluble vitamins, oxygen and minerals - Proteins attached to lipoprotein particles help suspend the particle in water (blood), so the fat rich particle can travel around the body - Act as pumps in cell membranes, transferring compounds from one side of the cell membrane to the other e.g. active transport of sodium and potassium

Role of water in the body

- Carries nutrients and waste products - Participates in metabolic reactions - Solvent for minerals, vitamins, amino acids, glucose and others - Lubricant and cushion around joints, inside the eyes, the spinal cord and in amniotic fluid during pregnancy - Regulation of body temperature - Maintains blood volume

Overview of Digestion

- Cells require a constant supply of nutrients - Nutrients are supplied via the blood of the circulatory system - Digestion - involves the mechanical and chemical breakdown of food, extraction of nutrients and breakdown of macronutrients - Absorption - is the transfer of nutrients from the lumen of the small intestine to the blood or lymphatic capillaries surrounding the digestive tract - Excretion - is the process of eliminating any remaining food waste after digestion and absorption are finished

Energy release - Carbohydrates

- Cellular respiration of Carbohydrates - The overall process of cellular respiration of carbohydrates follows the following equation: - Dietary carbs -> C6H12O6 (glucose) + 6O2 -> 6CO2 + 6H2O + 38 ATP (energy) - However this does not happen in one reaction or even one part of the cell, but in a series of stages spread over the cytoplasm and the mitochondria - There are four distinct stages: - Glycolysis - Acetyl-CoA formation - TCA (Krebs) Cycle - Electron transport chain (ETC)

How do calcium requirements change throughout the different life stages?

- Children and adolescents need to consume enough calcium and Vitamin D to create denser bones (growing) - For men >70 yrs and women >50 yrs, more calcium intake is required, to compensate bone loss involved with osteoporosis for the elderlies

Entero-hepatic recirculation of bile

- Cholesterol in bile is a critically important compound in the body - It is produced in the liver for many bodily functions including cell membrane function and hormone and vitamin D production etc. - The body has evolved a process by which it conserves cholesterol by reabsorbing bile after it is used for emulsification - Cholesterol products in bile are excreted into the duodenum and function as a fat emulsifier. They are then reabsorbed into the blood and returned to the liver for reuse

Zinc toxicity

- Chronic intake of slightly above RDA can lead to copper depletion and subsequent heart muscle degeneration - Acute very high doses (?2g/day) causes vomiting, diarrhoea, exhaustion and possible death - Nutrient reference values - Men (>19) = 14mg/day - Women (>19) = 8 mg/day

Lipoproteins differ in percentage composition as well as size

- Chylomicron - ~80% TG - ~7% Phospholipid - ~8% Cholesterol - ~2% Protein - VLDL - ~50% TG - ~20% Phospholipid - ~20% Cholesterol - ~10% Protein - LDL - ~10% TG - ~22% Phospholipid - ~48% Cholesterol - ~20% Protein - HDL - ~10% TG - ~20% Phospholipid - ~20% Cholesterol - ~50% Protein

Segmentation

- Chyme is subjected to localised contractions of circular smooth muscles which constricts the intestines into "segments" in a process called segmentation - Segmentation mixes the chyme with digestive juices and brings particles into contact with the wall of the GI tract so that nutrients can be adequately be absorbed

Protein - Provides building blocks for most of the body structures (e.g. muscles, blood, skin, bone, hair)

- Collagen (protein matrix) that makes up bone, skin, artery walls, ligaments - Replacement of dead or damaged cells (skin cells life span 30 days, GI tract cells replaced every few days, hair and fingernails continue to grow)

Important terms when considering protein quality

- Complementary proteins - Limiting amino acid - Poor quality protein - Complete protein

Peptide bond formation

- Condensation reactions involve the formation of a peptide bond between two amino acids - The -OH group from the acid end and the -H from the amino end (NH2) join and breakaway as H20, leaving a new bond joining the two amino acids - Dipeptides have two amino acids bonded together - The amino and acid terminal groups can then condense with another amino acid to form a tripeptide and so on - Polypeptides have several amino acids joined together

How can vegetarians improve the protein quality of their diet?

- Consume food with high protein content such as legumes, nuts, seeds, eggs, soy products, wholegrains (combinations of these, complementary proteins). - Consume different types of high protein ingredients during the day that complement each other (e.g. eat legumes and grains) - Tofu is a good source of protein.

Uncoupling proteins

- Coupled reactions - energy from the breakdown of a compound is used to create a bond in the formation of another compound - Uncoupled reactions - the energy is released as heat - Genes also code for proteins that influence the storing and expenditure of energy - Different efficiencies - In different types of fat

How can saturated fat intakes be decreased if they are above the recommended intake? List specific examples/modifications.

- Decrease fried food, eat more fruits and vegetables and lean meats, such as chicken and fish, decrease intake of butter, - Replace saturated fats in the diet with MUFA and PUFA - Avoid visible fats and chose lean cut meats - Select low-fat dairy products - Grill, bake, air-fry rather than deep fry

Vitamin B6 (Pyridoxine, pyridoxal, pyridoxamine) Deficiency and Toxicity

- Deficiency can lead to: - Weakness, - Kidney stones, - Pink eye, - Irritability, - Insomnia, - Anaemia, - Dermatitis, - Seborrheic dermatitis-like eruptions, - Depression - Eventually this can result in: - Growth failure, - Impaired motor function, - Convulsions, - Impaired immune function - Deficiency can be caused by drugs and alcohol - Many drugs interact with vitamin B6 - E.g. INH (isonicotinic acid hydrazide), a drug which inhibits tuberculosis bacterium, but inactivates vitamin B6 by binding to it and leading to a deficiency - Alcohol interacts seriously with vitamin B6 - Acetaldehyde from alcohol oxidation interferes with PLP coenzyme - PLP is separated from its enzyme and is excreted, therefore alcohol is responsible for vitamin B6 deficiency - Toxicity - Difficult to reach toxicity from normal food intake. Some women using concentrated supplement for PMS have suffered from nerve damage, bloating, depression, fatigue and headaches - Nutrient reference values for vitamin B6 are: - RDI = 1.3 mg/day for men/women (19-50 yrs) - RDI = 1.7 mg/day for men (>50 yrs) - RDI = 1.5 mg/day for women (>50 yrs) - RDI = 2 mg/day for women (lactating)

Vitamin B5 (Pantothenic acid) Deficiency

- Deficiency is rare (as B5 is ubiquitous in most foods) but results in general failure of bodily systems, with nervous system faults often being early signs (insomnia/fatigue), followed by nausea and vomiting - can result in acne and paraesthesia (pins and needles) - Toxicity symptoms - None known - Nutrient reference values for pantothenic acid are: - AI = 6 mg/day for men (>19 yrs) - AI = 4 mg/day for women (>19 yrs) - AI = 5 mg/day for women (pregnant) - AI = 6 mg/day for women (lactating)

Vitamin B12 (Various cobalamins) Deficiency

- Deficiency is rare due to poor diet but if it does occur, it is most likely in vegans and elderly people - Deficiency is usually due to poor absorption rather than inadequate intake. Major reasons being low stomach HCl levels (atrophic gastritis) or lack of intrinsic factor (pernicious anaemia) - Pernicious anaemia is characterised by large red blood cells (megablastic anaemia) as in folate deficiency, weakness and nerve dysfunction. All have a slow onset - Low B12 also leads to folate deficiency. Although the diet may have adequate folate, it is trapped as the inactive form (methyl-THF) due to the absence of sufficient B12 to activate it - Vitamin B12 deficiency has been often misinterpreted as folate deficiency and treated with folate supplements resulting in disability or death from the underlying, untreated Vitamin B12 deficiency - Incorrect info has been communicated to vegetarians that B12 can be obtained from mushrooms (only if unwashed and contaminated with faecal bacteria), spirulina tempeh and a number of other plant sources. There are not active B12 molecules but "analogous" that do not have B12 functionality in humans - Symptoms include: - Macrocytic anaemia, - Elevated methylmalonic acid and homocysteine, - Peripheral neuropathy (nerve cell damage), - Memory loss and other cognitive deficits. - It can also cause symptoms of mania and psychosis. - In rare extreme cases, paralysis can result - Nutrient reference values for Vitamin B12 are: - RDI: 2.4 ug/day for men/women (>19 yrs) - RDI: 2.6 ug/day for women (pregnant) - RDI: 2.8 ug/day for women (lactating)

Deficiency of vitamin K

- Deficiency is rare, but may occur in the following instances: - Malabsorption of fat (e.g. bile production fails, vitamin K absorption diminishes) - Medications interfere with vitamin K synthesis (e.g. antibiotics) and action in the body (e.g. warfarin and other anticoagulants) - Newborns because vitamin K does not cross the placenta and because bacteria in the GI tract takes weeks to establish. Newborns are given vitamin K at birth

Deficiency of vitamin E

- Deficiency is rare. Susceptible individuals are those who have digestive disorders or do not absorb fat properly (i.e. pancreatitis, cystic fibrosis, celiac disease) - Signs of deficiency include: - Erythrocyte haemolysis (vitamin E treatment corrects haemolytic anaemia) - Neuromuscular dysfunction (loss of control of body movements and speech) - Retinopathy (damage to the retina of the eyes that can impair vision)

Nutritional Risk factors

- Definition: A condition or behaviour associated with an elevated frequency of a disease - but not definitely known to cause the disease status - Clusters: Risk factors tend to cluster, which indicates a degree of interaction. - E.g. obesity, physical inactivity, high BP and high blood cholesterol are often seen together and all impact heart disease - Types of risk factors - Modifiable risk factors contributing to deaths: - Smoking, diet, physical inactivity, alcohol, obesity etc. - Non-modifiable risk factor - Genetics, age, sex - Measurable risk factors (biomarkers) - Blood pressure, plasma lipids, BMI, insulin resistance etc.

Diabetes

- Diabetes is a condition of poorly controlled glucose - There are two main types: - Type 1 diabetes - Pancreas is faulty and insulin is not produced, usually childhood onset, in the past it was fatal, now controlled with insulin injections (cause unknown) - Type 2 diabetes - Generally large amounts of insulin secreted but the insulin receptor on the body's cells are faulty and cells fail to respond to take up glucose as they should. Generally adult onset with fat gain also some genetic component (i.e. insulin resistance)

Bulimia Nervosa

- Diagnosed based on criteria such as: - Number and frequency of binge eating episodes - Inappropriate compensatory behaviours to prevent weight gain (e.g. self-induced vomiting or misuse of laxatives) - Self-evaluation unduly influenced by body shape and weight - Like the person with anorexia nervosa, the person with bulimia nervosa spends much time thinking about body weight and food but bulimia is not the same disease as anorexia nervosa - A bulimic binge is characterised by a sense of lacking control over eating - A vicious cycle of restricting, binging and purging often accompany this disorder

Binge-eating disorder

- Diagnosed based on recurring episodes of binge eating, with a marked sense of lack of control - Can occur in people of normal weight as well as those who are severely overweight

Anorexia Nervosa

- Diagnosed when someone has distorted body image that overestimates personal body fatness - Cannot be self diagnosed - After a few months - Most people have protein-energy malnutrition (PEM) that is similar to marasmus - Females suffer from amenorrhea (periods stop)

Nutrient composition of food is determined by chemical analysis

- Food is heated to 100ºC to remove the water content - Food is heated to 300ºC to burn the foods to remove the organic matter and leave only the mineral content (calcium, iron, zinc etc.)

Fibre

- Dietary fibres are non-starch polysaccharides (i.e. cellulose, inulin, lignans, pectins, oligosaccharides) - Fibre differs from starch in that the bonds between the glucose molecules cannot be broken by human enzymes - It passes through the body mostly undigested and thus contributes little to energy. Some fibre is fermented by gut bacteria in the large intestine, producing short-chain fatty acids (which provide a small amount of energy) - Cellulose is a polysaccharide consisting of linear chains of several hundred to many thousands of glucose units. It is a straight-chain polymer and the hydrogen bonds between each of the chains give its structural rigidity - Ruminant animals can breakdown cellulose with the aid of cellulase-producing bacteria

Nutrient density

- Dietary modelling process preference foods with the most nutrients for the least number of kj - Helped ensure people with low energy needs met recommended intake of all essential nutrients - This is why recommendation is 'mostly reduced-fat' dairy - Recent research suggests benefits of whole fat dairy

Food sources of Phosphorous

- Diets with adequate energy and protein would normally contain adequate phosphorous as it is found in all animal tissue, milk and most plant tissue, particularly legumes - Yoghurt, cheese, sunflower seeds and liver are particularly rich sources - Broccoli, Milk. Plain yoghurt, Cottage cheese, Sunflower seeds, Tofu, Liver - Deficiency - Dietary deficiency is unknown. Some drugs however bind to phosphorous making it unavailable leading to bone loss, weakness and pain - Toxicity - Rare but can lead to lowered calcium levels

Fat-soluble vitamins: A, D, E and K

- Differ from water-soluble vitamins: - Insoluble in watery GI juices - Require bile for absorption - Absorbed in to the lymphatic system - Many require transport (carrier) proteins - Stored in cells associated with fat, mainly in the liver and in adipose tissue - Less readily excreted; do not need to be replenished daily - The risk of toxicity is greater (can build up in the body) - A generally healthy diet provides adequate amounts - Fat-soluble vitamins are integrated into micelles and absorbed by simple diffusion. Inside mucosal cells, they are packaged into chylomicrons and enter the lymphatic system

Why is variety important?

- Different foods contain a different combination of nutrients - E.g. strawberries are rich in vitamin C but apricots are rich in beta-carotene - Variety can help to ensure nutritional adequacy - Also if a food contains a contaminant there is less chance of consuming a harmful amount if a variety of different foods are consumed - Eating a variety of foods can be more enjoyable

Calcium Nutrient Reference Values

- Difficult to determine as blood level does not reflect calcium status - Requirements have been determined by balance studies i.e. absorption must equal excretion - Men (19-70 years) RDI = 1000mg/day - Men (>70 years) RDI = 1300 mg/day - Women (>50 years) RDI = 1300 mg/day - Women (<50 years)/ Women (lactating)/Women (pregnant) RDI = 1000 mg/day - Men and women UL = 2500mg/day

Phosphorous (P) Nutrient Reference Values

- Difficult to determine as blood level does not reflect phosphorous status. Requirements have been determined by balance studies i.e. absorption must equal excretion - Men/Women/ Women (pregnant)/Women (lactating) RDI = 1000mg/day - Men and women UL = 3000-4000 mg/day

Disaccharides

- Disaccharides are formed from a condensation reaction, where separate monosaccharides link with a single oxygen and produce water - Hydrolysis reaction breaks a disaccharide into two monosaccharides with the help of a water molecule - Disaccharides include: - Sucrose (glucose + fructose), - Lactose (galactose + glucose), - Maltose (glucose + glucose)

The hypothalamus's role in food consumption

- Dozens of chemicals in the brain participate in appetite and energy balance - These chemicals are complex in behaviour - E.g. Neuropeptide Y can cause food cravings, decrease energy expenditure and increase fat storage

The small intestine's secretions

- Duodenum - place where most digestion occurs - Delivery of chyme/HCl - Liver/gallbladder - delivers bile (emulsifier) - Pancreas - delivers pancreatic juice (digestive enzymes and bicarbonate) - Brush border enzymes - Jejunum - place where most absorption of nutrients occurs - Ileum - absorption of some important nutrients (vitamins B12, A, D, E and K)

Protein - Blood clotting

- During blood vessel injury, the protein collagen is exposed - Platelets adhere to the exposed collagen - Substances are secreted that induce platelets to aggregate and initiate a cascade of reactions leading to the formation of a blood clot - This reaction involves numerous proteins - Process results in formation of fibrin strands (protein) that cross link platelets and red blood cells to form a stable clot - Fibrinogen and prothrombin are two of the clotting factor proteins found in blood

Cori Cycle

- During extreme exertion O2 is inadequately supplied to the mitochondria and pyruvate is converted to lactic acid rather than entering the mitochondria - Relaxation allows the blood to clear lactic acid to the liver where it is reverted back to glucose - This glucose is then available to be returned to cells for glycolysis - A critical aspect of lactate (lactic acid) production is NAD regeneration for glycolysis - Lactic acid formation generates a little energy, but the liver uses energy to reconvert lactic acid to glucose

Fat cell overview

- During growth fat cells increase in number - When energy intake exceeds energy expenditure fat cells increase in size - When fat cells have enlarged and energy intake continues to exceed energy expenditure, fat cells may increase in number again - With fat loss, the size of the fat cells shrinks but not the number

Fat cell expansion

- During positive energy balance, fat cells accumulate triglycerides and become larger - Obesity due to increase in size of fat cells is called hypertrophic obesity

Schofield equations can be used to calculate approx. BMR

- E.g. for males 18-29 yrs BMR = (63 x weight in kg) + 2896 - E.g. for females 18-29 yrs BMR = (62 x weight in kg) + 2036

Roles of vitamin A in the body

- Each form of vitamin A has specific tasks in the body - Retinol - Supports reproduction - Major transport and storage form - Retinal - Active in vision - Retinoic acid - Acts like a hormone - Regulates cell differentiation, growth and embryonic development

The changing relationship of diet and health

- Early nutrition research was primarily focussed on diseases of nutritional deficiency, which were once very common when diets were poor and unbalanced - In modern times however most nutritional research is focussed on chronic diseases, which in general result from over-nutrition in an environment where food is plentiful - In particular the food available in western societies has become more processed and hence more energy-dense, leading to excess energy intake and weight gain as fat and chronic diseases such as CVD, cancers, diabetes etc. - Micronutrient deficiencies can still occur if a diet is processed food dominated, but in a society where broad food type availability is common it shouldn't be an issue

Health effects of low GI diets

- Eating a low GI diet has been linked to improvements in: - Body weight (although research findings are mixed) - Blood lipids - Blood glucose control (type 2 diabetes) - However, the usefulness of the GI has been debated because: - Relatively few foods have been tested - Responses to food vary widely between individuals - Not always indicated on nutritional levels and is not intuitively apparent - Cooking method and how its eaten (i.e. mixed meal, standard serve vs 50g CHO portion) can effect the glycaemic response

Overriding hunger and satiety

- Eating can be triggered by other signals, e.g. stress or anxiety - Cognitive influences to overeat might include: - Large portion sizes - Memories - Intellect - Social interactions - Hunger can also be suppressed by signals other than satiety, such as: - Stress and how people perceive it - Eating disorders - Enforced discipline

There are positive and negative associations with food choice, such as:

- Eating for emotional comfort - Body weight and image - Political views or environmental concerns - The nutrition and health benefits of foods, such as whole modified or fortified foods

Electrolytes

- Electrolytes are products of the salts that dissolve in water and dissociate to produce ions, either positive (cations) or negative (anions) - E.g. sodium chloride (NaCl) -> Na+ + Cl- - Examples of electrolytes: - Sodium (Na+) - Calcium (Ca+) - Chloride (Cl-) - Potassium (K+) - Magnesium (MG2+) - Phosphate (PO4-) - Bicarbonate (HCO3-) - Sulphate (SO4(2-)) - Iron (Fe3+) - Electrolyte solutions in the body usually have equal total positive and negative charges (mEq), not equal numbers of individual ions - Charge density and ion type outside a cell is different to inside the cell and is measured in milliequivalents (mEq) i.e. there may be a higher concentration of positive ions outside a cell than inside - One of the principle functions of electrolytes is to control movement of water into and out of cells, by the action of osmosis

Healthy Eating patterns

- Emphasise nutritional adequacy - Adequate kilojoules are provided by a balanced diet of fruits, vegetables, whole grains, lean meats and alternatives and lower-fat milk products - Eat small portions - Use small plates and utensils - Lower energy density - Eat from the five food groups - Avoid excessive amounts of nutrient poor, energy-dense discretionary foods - Focus on fibre - High-fibre foods tend to be low in energy and high in nutrients - Promote satiety - Choose fats sensibly - Choose foods with lowered fat content - Avoid excessive amounts of saturated fat - Select carbohydrates carefully - Each high-fibre, low-GI options in the appropriate volumes to complement the other five food groups - Watch for empty kilojoules/discretionary choices - Be cautious of excess energy from foods rich in fat, sugar and/or alcohol

The 2013 Australian Dietary Guidelines - Guideline 4

- Encourage, support and promote breastfeeding - Exclusive breastfeeding for around 6 months

Metabolism Intro

- Energy metabolism involves extraction of energy from carbohydrates, proteins (amino acids) and lipids (fatty acids and glycerol) - The cytoplasm in the cell contains no oxygen. The initial stages of cellular respiration (glycolysis) occurs there and is therefore anaerobic. It thus has a low efficacy of energy release molecules - Once the initial breakdown products of carbohydrates, plus fatty acids and amino acids enter the oxygen-rich environment of the mitochondria, high levels of energy are released in an aerobic process. This involves the TCA cycle and the electron transport chain (ETC) - The breakdown of energy-containing molecules is termed catabolism - The synthesis of fat and other molecules from the breakdown of products when energy surplus occurs is called anabolism

Weight-gain strategies

- Energy-dense foods can be included, but choose wisely - Regular meals each day must become a priority - Use large portions and expect to feel full - Consume extra snacks between meals - Juice and whole milk are easy ways to increase kilojoules - Exercising to build muscles will support increases in muscle mass

Action to prevent obesity in Victoria

- Engage and support local communities to develop and lead their own healthy eating and physical activity initiatives - Protect children from unhealthy food and drink marketing - Implement a state-wide public education campaign to encourage healthy eating - Implement initiatives to improve family diets, particularly in children's early years - Support schools to increase student's physical activity and physical literacy - Increase the scope of and strengthen compliance with the existing school canteens and other school food services policy - Develop a whole-of-government policy that requires healthy food procurement - Develop and implement a strategy to get Victorians walking more

The 2013 Australian Dietary Guidelines - Guideline 2

- Enjoy a wide variety of nutritious food from the five food groups every day and drink plenty of water - Plenty of vegetables, including different types and colours and legumes/beans - Fruit - Grain (cereal) foods, mostly wholegrain and/or high cereal fibre varieties, such as breads, cereals, rice, pasta, noodles, polenta, couscous, oats, quinoa and barley - Lean meats and poultry, fish, eggs, tofu, nuts and seeds and legumes/beans - Milk, yoghurt, cheese and/or alternatives, mostly reduced fat (reduced fat milks are not suitable for children under 2 years old) - And drink plenty of water

Further fat cell development

- Enlarged fat cells stimulate the production of more fat cells - People with obesity have more fat cells than healthy weight people and their fat cells are larger

Fat loss

- Enzymes controlling the release of lower body fat are less active in women than men - Release of upper body fat is similar in men and women - Rate of fat breakdown is lower in women than men - Overall, women find losing fat from hips and thighs difficult

Essential and non-essential amino acids

- Essential amino acids must be supplied by the foods people consume - Methionine - Threonine - Histidine - Valine - Phenylalanine - Isoleucine - Tryptophan - Leucine - Lysine - Conditionally essential amino acids are amino acids that are normally non-essential but essential under certain conditions (e.g. illness, trauma, PKU or if the diet cannot supply the amino acid) - Non-essential amino acids, also called dispensable amino acids, are ones the body can create - Alanine - Arginine - Asparagine - Aspartic acid - Cysteine - Glutamic acid - Glutamine - Glycine - Proline - Serine - Tyrosine

Essential Fatty Acids

- Essential fatty acids (18:2n6 and 18:3n3) cannot be made by the body - Classic deficiency symptoms include growth retardation, reproductive failure, skin lesions, kidney and liver disorders - Linoleic acid (18:2n6) from vegetable oils is from the omega-6 family and can make arachidonic acid (20:4n6) in vivo, a conditionally essential fatty acid, also consumed preformed in meats and fish - Alpha-Linolenic acid (18:3n3) from canola, flax and some other plants is essential for health and is from the omega-3 family. It can be turned into EPA (20:5n3) and DHA (22:6n3) in vivo, but not well in humans - These long chain omega-3 fatty acids (EPA and DHA) are important for eyes, brain and heart structure and function and can be consumed preformed from animal foods (fish and grass fed red meat) - Eicosanoids, made from arachidonic acid (20:4n6) and EPA are 'hormone like substances' that include prostaglandins, thromboxanes and leukotrienes, which control many cell, tissue and organ functions

Recommended dietary intakes of protein

- Estimates are based on essential amino acid needs - Recommended Dietary Intake (RDI) - Grams/kg body weight/day = 0.84g/kg/day for adult males and 0.75g/kg/day for adult females - Acceptable macronutrient distribution range (ADMR) - Percentage of energy = 15-25% - Assumptions: - People are healthy - Protein is mixed quality - The body will use protein efficiently

Nutrition assessment of individuals

- Evaluates the many factors that influence or reflect nutritional health - Historical information regarding diet, healthy statis, drug use and socioeconomic status is gathered - Anthropometric data measures physical characteristics including height, weight, body fat composition, waist: hip ratio and BMI - Physical examinations, including hair, eyes, tongue, fingernails etc. require skill but can reveal possible nutrition imbalances - Laboratory tests detect early signs of malnutrition, particularly blood and urine tests, where measurements are compared with population normal values

Health effects of dietary fat

- Examination of blood lipid profile is an indicator of health impact of dietary fat - Factors to consider include: - Some saturated fatty acids cause blood cholesterol levels to rise - The short chain saturated fatty acids and stearic acid (18:0) do not raise blood cholesterol levels - Only medium chain (C12-16) saturated fatty acids increase blood cholesterol levels - Some trans fats behave like saturated fatty acids - PUFA in the diet lowers LDL cholesterol - Intake of MUFA and cholesterol have no significant effect on blood cholesterol levels - Omega-3 fatty acids in the diet lower blood triglycerides and CHD risk - Exercise and female sex hormones increase HDL cholesterol levels and therefore decrease risk of CVD

What is a healthy body weight?

- Excess body fat is a risk factor for several serious diseases - E.g. heart disease, type 2 diabetes and some cancer - Weight is a health issue - not just a fashion - Health outcomes should be used to determine guidelines for healthy weight - Body mass index (BMI) measures relative weight for height - BMI = weight (kg) / height (m2) - Underweight BMI = <18.5 - Overweight BMI = >25 - Obese BMI = >30 - Different cut-offs for older adults and different ethnic groups - BMI does not reflect body composition, so is not relevant to all population groups

Fat cell development

- Excess energy is stored in fat cells - Fat cell numbers increase more rapidly in later childhood and early puberty - After we stop growing, fat cell numbers continue to increase whenever energy balance is positive - Obesity due to an increase in the number of fat cells is called hyperplastic obesity

Drawbacks of a high fibre diet

- Excessive intake of dietary fibre can: - Cause malnourishment (too much bulk) in some individuals (elderly and young children) - Cause abdominal discomfort, gas, diarrhoea and distention due to excessive fermentation - Inhibit absorption of nutrients (mineral absorption) by speeding up GI transit time and binding to minerals

Vitamin B6 (Pyridoxine, pyridoxal, pyridoxamine) Functions

- Exists in 3 forms - All can be converted to the active coenzyme forms: PLP (pyridoxal phosphate) and PMP (pyridoxamine phosphate) - PLP + NH3 -> Pyridoxamine phosphate (PMP) - Pyridoxamine phosphate -> PLP + NH3 - The three forms consumed in our diet are (easily inter-converted): - Pyridoxal - Pyridoxine - Pyridoxamine - Primary function of the PLP coenzyme is in amino acid metabolism - PLP has the ability to transfer amino groups from one amino acid to other compounds such as keto acids, therefore helping to synthesise non-essential amino acids - Also involved in protein and urea metabolism - Involved in conversion of the amino acid tryptophan to niacin and the neurotransmitter serotonin - Involved in the synthesis of haem protein, nucleic acids and lecithin - Influences cognitive development, immune function and steroid hormone activity - Different to other water-soluble vitamins because it can be stored in muscle tissue

The latest and greatest weight-loss diet - again

- Fad diets appeal for many reasons - They promise fast results with minimal effort, decreasing choice in diet - After completing a fad diet, people often put on more weight than they started at pre-diet - They can be expensive to complete, dangerous for health and are not ideal compared to making diet and lifestyle changes that are more long-lasting

Trans fatty acids and cholesterol in the diet

- Food sources of elaidic acid (18:1 trans-9) include deep-fried foods using vegetable shortening, cakes, biscuits, doughnuts, pastry, crackers, snack chips, margarine, imitation cheese - This trans fatty acid does raise blood cholesterol levels - Food sources of naturally fatty acids (CLA and vaccenic acid) are meat and diary products including breast milk - Neither alter blood cholesterol levels and both appear to have health benefits - Also dietary cholesterol itself has little or no effect on blood cholesterol levels - Food sources of cholesterol include egg yolks, milk products, red meat, poultry, fish and particularly shellfish (but not plants)

Food sources of iron

- Main sources are meat, fish and poultry - Wholegrains, cereals, legumes, tofu - Vegetables in particular dark green Broccoli Tomato juice - Vitamin D helps to absorb the calcium effectively

During periods of fasting, how are metabolic fuels used differently compared to their use in people with a healthy consistent diet?

- Fasting stage 1 - Liver and muscle glycogen stores are broken down to glucose and used as energy for the brain, nervous system, and red blood cells as well as energy for other cells. - Body fat stores are broken down to fatty acids which are used as energy for cells (but not brain, nervous and red blood cells). - Fasting stage 2 - Body proteins are broken down to amino acids which are broken down to glucose and ketone bodies (loss of nitrogen in urine). Glucose and ketones are used for energy in the brain, nervous system and other cells. - Body fat is broken down to fatty acids which are used for energy in other cells. - Fatty acids are also broken down to ketone bodies which are used for energy for other cells and the brain and nervous system. - Negative effects/symptoms of starvation - Muscle wasting, organ failure, decreased immunity - Decreased heart rate, respiratory rate, metabolic rate and body temperature - Impaired vision, depression and anxiety

Body fat determination

- Fatfold measures - Hydrodensitometry - Bioelectrical impedance - Waist: hip ratio - Waist: hip ratio should always be <1 (waist should be smaller than hips) - Body mass index (BMI) - Body weight/height^2 - Mortality risk follows a J-curve (increased risk at extremes)

Types of PUFAs

- Fatty acids can have extra carbons added to make them longer or more double bonds added to make them more unsaturated by various enzymes in your body - Humans do this well for omega-6 and 9 fatty acids, but are very poor at doing this with omega-3 PUFA - ALA -> EPA ~5% - ALA -> DHA ~0.1% - Also humans cannot interconvert fatty acids between series i.e. once an omega-6 fatty acid is consumed, it may become longer and have more double bonds but remains an omega-6 fatty acid - Shorter chain fatty acids can be found in both plants and animals - Longer chain fatty acids are found in animals only

Fructose and FODMAPS

- Fermentable Oligosaccharides - Fructans; wheat, rye, garlic, artichokes, inulin, oligosaccharides - Galactans: beans, lentils and chickpeas - Disaccharides - Lactose: milk, yoghurt, ice cream, pudding and custard - Monosaccharides and - Fructose (in excess of glucose): honey, watermelon, apples, asparagus and sugar snap peas - Polyols - Sorbitol/mannitol: sugar-free gum, blackberries, apples, pears, peaches, cauliflower, mushrooms and snow peas - FODMAPS are a large group of short-chain carbohydrates and sugar alcohols that are found in all sorts of foods and drinks - These sugars can be poorly absorbed in the small intestine and are fermented by bacteria to produce gas - For some people a diet in FODMAPS can cause a range of abdominal symptoms such as bloating, excess wind, distension, abdominal pain, constipation or diarrhoea - Following a low FODMAP diet can help manage these abdominal symptoms - 75% of people with IBS experience relief from their symptoms with a low FODMAP diet

Complex carbohydrates

- Few (oligosaccharides) or many (polysaccharides) monosaccharides bound together in straight or branched chains - Three important types of polysaccharides: - Glycogen - Storage form of glucose in the body - Provides a rapid release of energy when needed - Starches - Storage form of glucose in plants - Found in grains, tubers and legumes - Fibres - Structural part of plants - Yield little energy

Functional (Globular) vs Structural (Fibrous) proteins

- Fibrous proteins - Long and narrow shape - Structural purpose - Repetitive amino acid sequence - mechanically strong - Less sensitive to changes in pH, temperature etc. - more durable - E.g. Collagen, myosin, fibrin, actin, keratin, elastin - Generally insoluble in water - Globular proteins - Round/spherical shape - Functional purpose - Irregular amino acid sequence - More sensitive to changes in pH, temperature etc. - less durable - E.g. Enzymes: haemoglobin, insulin, immunoglobulins - Generally soluble in water - great transport molecules

Digestion within the large intestine: absorbing and eliminating

- Fluids and some minerals are absorbed - Some digestive fibre from the seeds, whole-wheat bread, peanut butter and banana is partly digested by the bacteria living in the large intestine and some of the products are absorbed - Most digestive fibre passes through the large intestine and is excreted as faeces: some fat, cholesterol and minerals bind to the fibre and are also excreted

Vitamin B9 (Folate) as a methyl group donor

- Folate and vitamin B12 interact substantially and are important in cell division and multiplication and a number of other metabolic steps where transfer of a methyl group is critical - I.e. Vitamin B12 acts as the transfer agent, transferring a methyl group from folate to the compound requiring a methyl group

How does folate impact health?

- Folate deficiency leads to impaired cell division and protein synthesis. This affects DNA, and GI tract mucosal cells the most. - Folate donates a methyl group to B12 - this activates both compounds. A deficiency in folate (or B12) means that neither of these compounds are activated sufficiently. - Folate deficiency results in visually large immature red blood cells (megablastic anemia) - Low levels of folate during pregnancy increase the risk of neural tube defects in the child

Vitamin B9 (Folate) Digestion, transport and storage

- Folate in food has a chain of glutamates (amino acids) attached (thus folate is said to be in a bound form). Intestinal cell wall enzymes remove all but one glutamate (free form) then attach a methyl group. This form of folate (methyl-THF) is inactive - Absorption into blood follows, then storage in cells occurs as the inactive methyl-THF form. Excess folate is secreted by the liver into the gall bladder with bile. The intestines reabsorb some of this folate and return it to the liver (enterohepatic circulation), any excess transits the GI tract and is removed in faeces

Energy metabolism overview

- Food -> energy nutrients (proteins + carbohydrates + lipids) - Proteins -> amino acids - Amino acids build new proteins - Carbohydrates -> glucose - Glucose travels to the liver and forms glycogen for energy storage - Lipids -> Glycerol and fatty acids - Glycerol and fatty acids are stored for long term energy storage

Diet Planning Principles

- Food choices made over years influence the body's health - Consistently poor choices increase the risk of developing chronic diseases - Ideally, we need to create a diet that supports health - Fortunately, most foods provide several nutrients - Wise diet-planning involves selecting a combination of foods that deliver a full array of nutrients

Protein - Antibodies

- Giant protein molecules that combat antigens (foreign invaders) - Without sufficient protein, the body can't manufacture its army of antibodies

Vitamin A recommendations

- Food sources of vitamin A (retinoids and carotenoids) are expressed in micrograms of retinol equivalents (RE) - 1 μg retinol = 1 RE = 6 μg beta-carotene - RDI men = 900 μg RE/day - RDI women = 700 μg RE/day - Upper level for adults = 3000 μg RE/day

Nutrients in foods and the body

- Foods contain organic and inorganic compounds - Organic compounds = protein, carbohydrate, lipids and vitamins - Inorganic compounds = minerals and water - Our bodies can derive all the energy, structural materials and regulating agents we need from the foods we eat - Chemical analysis of your body would show that it is made of materials similar to those found in foods - We are a collection of atoms, molecules, cells, tissues and organs. There is truth in the saying 'you are what you eat' - Cells die (either lost or broken down) and new cells are created - Oldest red blood cell is ~120 days old, - Intestinal lining cells are renewed every 3 days - Skin is totally replaced every 7 years - Food replenishes bodily requirements for structure and energy - It is the nutrients found in food that makes this possible

Diet planning principles - Moderation

- Foods rich in fat and sugar tend to provide a high amount of energy in relation to the other nutrients - These foods add enjoyment to the diet - A person practising moderation would eat 'empty calories/kJ' only occasionally

Recommended dietary intake for Carbohydrate

- For carbohydrate intake, recommendations are based on a proportion of one's energy requirement - AMDR: 45-65% of total energy intake - Predominantly from low energy density and/or low glycaemic index foods - For an average adult diet of 8000kj, this equates to CHO contributing 3600-5200kj (200-325 gm) - Individual dietary requirements may be higher or lower depending on age, gender, height, weight and physical activity levels

The role of bile

- For lipids to break down they must be drawn into the watery environment of the GI tract - This process is termed emulsification and is made possible by the action of bile - Bile is a mixture of liver produced substances, the main ingredient (bile acids) is made from cholesterol - Active form is a bile salt or bile acid that is combined with an amino group - Bile made from cholesterol - Bile is made in the liver - Bile is stored in the gall bladder - Bile has a non-polar and a polar end - allows its emulsifying property - Amino acid end = hydrophilic - Cholesterol end = hydrophobic

Vitamin B 12 (Various cobalamins) Food Sources

- Found exclusively in foods from animals such as meat, milk, cheese, eggs - Vegans need to consume fortified soy milk, fortified TVP (textured vegetable protein, soy based) or take supplements - Miso (soybean paste) spirulina, yeast and mushrooms do not contain Vitamin B12 even though many non-scientific references suggest they do - Mushrooms may have some Vitamin B12 on them from contamination by faecal matter from the growing medium - Vitamin B12 is produced by bacteria in the GI tract of animals (even humans) so is rich in faecal matter

Phospholipids in the body

- Found mainly in the membrane of cells where they make up an important part of the lipid bi-layer structure - The fatty acids in the phospholipids of the cell membrane vary considerably. However most are Mono-unsaturated fatty acids and polyunsaturated fatty acids and the specific types with differing lengths and shapes control much of the cell membranes fluidity (what is able to pass through)

Facts about cholesterol

- Found only in animal foods - Dietary cholesterol consumption has little or no effect on blood cholesterol - The liver produces cholesterol and the blood level rises due to saturated fat intake causing the liver to make more cholesterol and remove less - Some cholesterol in the body is essential - Cell membranes contain cholesterol as part of their structure - Several hormones and vitamin D are made from cholesterol in the body - However high cholesterol levels in blood LDL is linked to CVD

Hydrogenation

- Full hydrogenation removes all of the double bonds - Partial hydrogenation only removes some double bonds - This occurs in margarine manufacture and trans formation is an artefact (unintended side reaction)

Protein and denaturation

- Functional protein showing a quaternary structure - Heat, acid or other conditions alters the intramolecular bonds of the protein - Unfolding of the polypeptide structure which results in loss of function

Health claims levels

- General level - Refer to a nutrient or substance in a food, or the food itself, and its effect on health. Must NOT refer to a serious disease/biomarker of a serious disease - E.g. calcium for healthy bones and teeth - Companies can self-substantiate a food-health relationship - Companies can use one of more than 200 pre-approved food-health relationships - High level - Refer to a nutrient or substance in a food and its relationship to a serious disease/a biomarker of a serious disease - E.g. diets high in calcium may reduce the risk of osteoporosis in people 65+ yrs - E.g. phytosterols may reduce blood cholesterol - Companies must apply to FSANZ for pre-approval of a food-health relationship - Companies can use one of 13 pre-approved food-health relationships

Causes of obesity

- Genetic deposition - Environment - Metabolic - Culture - Behavioural - Psychological - Socioeconomic

Genetic and epigenetic causes of obesity

- Genetics play a true causal role in very few cases of obesity - E.g. Prader Willi syndrome - excessive appetite, massive obesity - Little change in the human genes over the past 30 years, but massive changes in rates of overweight and obesity - More than 100 sites of the human genome associated with obesity and fat distribution - Epigenetics = influence of environmental factors (e.g. diet) on gene expression - Adopted children - weight more similar to biological parents than adoptive parents - Twin studies - identical twins are more likely to weigh the same than fraternal twins - Role for genetics in determining susceptibility to obesity - Not necessarily cause obesity - Some people gain more weight than others when over-consuming a similar amount - Some people lose more weight than others when over-exercising a similar amount

Ghrelin, the hunger hormone

- Ghrelin (Gastric Hormone Released IN (empty state)) is a hormone, secreted by stomach cells, which tells the brain when it's empty or full - Empty stomach stimulates ghrelin release - Ghrelin receptors are found in the hypothalamus - Full stomach stops ghrelin release - In addition to regulating appetite control, ghrelin plays an important role in glucose and energy homeostasis, cardio-protection and muscle atrophy

Palm oil production expansion

- Global production of palm oil has doubled over the last decade. By 2000, palm oil was the most produced and traded vegetable oil accounting for 40% of all vegetable oils traded internationally. By 2006, the percentage gad risen to 65% - New plantations are being developed and expanded in Indonesia, Malaysia and other Asian countries, as well as in Africa and South America - But this expansion comes at the expense of tropical forest - which forms critical habitat for a large number of endangered species, as well as an important atmospheric carbon trap

Glucose for brain function

- Glucogenic amino acids can also be used to fuel the CNS activity via glucose formation from pyruvate (gluconeogenesis), whereas dietary fatty acids are unable to do this - Thus dietary protein will maintain brain function better than fat - In the case of a high protein diet, nitrogen may be a problem. Due to increased urea there is a greater water loss in the urine. Also the liver can only make a certain amount of urea per day (MRUS) - Ammonia from proteins above the level that can be dealt with (liver production of urea) will lead to a toxic effect

Nutrients for energy summary

- Glucose and fatty acids are primarily used for energy, amino acids to a lesser extent - Glucose is made from all carbohydrates, most amino acids and the glycerol portion of fat - Glucose can be made into non-essential amino acids if nitrogen is present - All energy-yielding nutrients consumed in excess can contribute to fat storage - The conversion of glycerol to pyruvate is easy because they are both 3C compounds - Fatty acids-to-acetyl-CoA reactions are called fatty acid oxidation - Fatty acids cannot be used to synthesise glucose as acetyl-CoA cannot exit the mitochondria - Glucose must be available to provide energy to the red blood cells, brain and nervous system, as these cannot use fatty acids or amino acids, hence the advantage of amino acids and glycerol (glucogenic) over fatty acids (not glucogenic) for brain function

Severe fasting

- Glucose is needed for the brain and nerves as they cannot use fatty acids or amino acids (unable to cross the blood-brain barrier) - Once glycogen storage is exhausted another glucose source is needed. Protein (body tissue) can be converted to glucose initially (glucogenic amino acids only) - Lastly comes a shift to ketosis - Ketones are produced when glucose becomes less available - Ketones can cross the blood-brain barrier and are produced from fatty acids and ketogenic amino acids - Production of ketones is termed ketosis, which will cause a suppression of the appetite and slowing of metabolism (BMR) - Eventually symptoms of starvation become evident: - Muscle wasting, organ failure, decreased immunity - Decreased HR, respiratory rate, metabolic rate and body temperature - Impaired vision, depression and anxiety

Lipid metabolism

- Glycerol and fatty acids from triglycerides enter the energy metabolism pathway at different points - Glycerol is a 3 carbon compound and easily converted to pyruvate in the cytoplasm. The pyruvate can enter the mitochondria and form acetyl-CoA and be metabolised for energy or be converted to glucose via gluconeogenesis - Fatty acids from lipids are broken down into two carbon segments and enter the mitochondria where they are converted to acetyl-CoA directly and metabolised for energy through the TCA cycle and ETC - If energy is not required, the acetyl-CoA units are re-joined to form fatty acids or storage fat - Pyruvate in cytoplasm can be reconverted to glucose by a reverse glycolysis pathway "gluconeogenesis" i.e. making new glucose - Hence part of the fat molecule (glycerol) can be converted into a carbohydrate - NAD coenzyme molecules collect Hydrogens with high energy electrons from reactions attaching CoA to acetyl (2 carbon) groups - The NADH produced then travels from the cytoplasm into the mitochondria and on to the ETC to release energy - Glycerol can enter glycolysis in the cytoplasm. Hence it can be conveyed to pyruvate and eventually acetyl-CoA in the mitochondria or it can undergo gluconeogenesis and be converted to glucose

What does energy metabolism consist of?

- Glycolysis (cytoplasm) - Tricarboxylic acid cycle (Krebs cycle or Citric acid cycle) (mitochondrial fluid space) - Electron transport chain (mitochondrial inner membranes)

Vitamin B3 (Niacin (nicotinic acid), Nicotinamide) Food sources

- Good sources include liver, fish, mushrooms and fortified breakfast cereal - Chicken breast - Canned tuna in water - Niacin can also be made in vivo from the amino acid tryptophan - Dietary protein contributes to niacin supply, therefore protein-rich diets are never deficient in niacin. However it takes 60mg of tryptophan to make 1 mg of niacin

Zinc Deficiency

- Growing children need lots of dietary zinc for correct growth and sexual maturation - Middle-Eastern diets were often low in zinc and high in fibre and phytates - Zinc deficiency will result in impaired pancreatic and GI function - Zinc deficiency will lead to: - Impaired pancreatic and GI function - Restricted chylomicron formation - Impaired immune response - Reduced function of the CNS - Reduced thyroid function and metabolic rate - Impaired vitamin A metabolism - Night blindness - Lowered sperm count - Anorexia - General malnutrition and sickness - Impaired taste sense - Impaired growth and sexual maturation

Haem iron v Non-Haem iron

- Haem proteins come from animal protein - There are specific carriers for absorbing Haem proteins - Absorption of non-haem iron is less efficient than the absorption of haem iron - Haem-iron in animal foods is much more efficiently absorbed - Only foods derived from animal flesh provide haem, but they also contain non-haem iron - All the iron in foods derived from plants is non-haem iron - Haem accounts for about 10% of the average daily iron intake, but 35% of the iron absorbed

Surgery for severe obesity: gastric bypass

- In a gastric bypass, the surgeon constructs a small gastric pouch and connects it directly to the jejunum so that the flow of food bypasses a substantial portion of the small intestine - Limits the amount of food that may be eaten without discomfort - Altered flow of food through the GI tract - Patients may develop nutritional inadequacies e.g. absorption of nutrients may be reduced

Special role of protein

- In energy terms, our diet mainly consists of carbohydrates (~50%), fat (35%) and protein (~15% most of which isn't metabolised for energy) - Protein's role in providing energy is limited, however it has other critical functions such as: - Muscle tissue (structural) - Skin (structural) - Enzymes (cellular reactions) - Hormones (messengers) - Antibodies (immune function)

Vitamin B6 (Pyridoxine, pyridoxal, pyridoxamine) Food sources

- Main sources include meat, fish, poultry, vegetables and fruit. There is a lower bioavailability from plant-derived foods and it can be lost through heating foods - Fortified cornflakes, Broccoli, Banana, Tomato juice, Watermelon

Benefits of a high fibre diet

- Heart disease - Lowers cholesterol levels. Soluble fibres increase cholesterol excretion and bacterial by-products inhibit cholesterol synthesis - Displaces energy from fats in the diet, including saturated fats - Associated increases in vegetable proteins and phytochemicals - Gastrointestinal health - Normalises bowel movements. Alleviates/prevents constipation by adding bulk to the stool (both soluble and insoluble fibres), also softens stool by holding water (soluble fibre) - Helps prevent and treat haemorrhoids - Helps prevent diverticulitis (small pouches) through stimulating GI tract muscles - May help prevent appendicitis - Cancer - Protects against colon cancer - Bacterial fermentation activates cancer-killing enzymes and inhibits inflammation - Associated increases in nutrients and phytochemicals - Weight management - Less 'energy dense', which means they have fewer calories for the same volume of food - Delays hunger and tends to be more filling - Associated increases in nutrients and phytochemicals - Diabetes - Slows digestion. Slows glucose absorption - Helps weight management - Helps prevent diabetes. Higher intakes of insoluble fibres is associated with lower risk of type 2 diabetes - Soluble fibre controls the rate of starch/sucrose digestion by controlling the release of starch/sucrose from the food matrix - As prebiotics - Promotes beneficial bacterial growth in the colon

Health effects of high protein intake

- Heart disease and stroke - Foods high in animal protein also tend to be high in saturated fat - High blood levels of amino acid, homocysteine, has been linked to the early development of heart disease. However, elevated homocysteine is associated with low levels of vitamins B6, B12 and folate, as well as drinking alcohol and smoking - Cancer - High intakes of animal protein is associated with some cancers, but its difficult to disentangle the effects of fat. Colon cancer may be associated with red and processed meats - Adult bone loss (osteoporosis) - High protein intake is associated with increased calcium excretion. Whether this influences bone health depends on the adequacy of calcium in the diet. However, a 2017 systemic review and meta-analysis did not find support for this association - Weight control - Weight loss from increased dietary protein is a combination of both increased water loss through urine (to excrete more nitrogen-containing urea) and the fact that protein-rich foods are highly satiating, so you eat less - Only effective for weight loss if kilojoules are low, but need to maintain adequate intakes of fruits, vegetables and whole grains - Kidney disease - High protein intake increases the work of the kidneys - A high protein intake does not seem to cause kidney disease - However, people with CKD should avoid high protein diets

What are the health risks of consuming more protein-containing foods?

- Heart disease and stroke: - High protein intake → high saturated fat intake → risks for cardiovascular disease - High protein intake → high homocysteine (amino acid) intake → risks for developing heart disease - Cancer: colon cancer may be associated with red and processed meats - Osteoporosis: high protein intake is associated with increased calcium excretion, which will have a negative impact - Kidney disease: high protein intake increases the work of the kidneys → risks for developing renal disease

Vitamin C deficiency

- Helps maintain blood vessel integrity through collagen formation. Therefore depleted vitamin C leads to bleeding gums and subcutaneous bleeding followed by failure to make collagen - This leads to internal haemorrhaging, muscle degeneration, rough dry skin, bone degeneration, infections, hysteria, depression and death - Early symptoms known as scurvy involve bleeding gums - Symptoms are cleared within 5 days by simple vitamin C supplementation of 100 mg per day - Recommended daily intake of vitamin C - Varies between countries - Nutrient reference values for Vitamin C are: - RDI: 45 mg/day for men/women (>19 yrs) - RDI: 60 mg/day for women (pregnant) - RDI: 85 mg/day for women (lactating) - Many stresses deplete the body therefore increased intake is needed - E.g. smoking, oral contraceptives, barbiturates (drug that acts as a CNS depressant), aspirin - Increased vitamin C is required for healing of burns and wounds for collagen formation

Zinc in selected foods

- Highest in protein rich foods, particularly shellfish, meat, poultry, beans and diary products - Poorly absorbed from cereal grains

Diet and Chronic Diseases

- Historically nutrient deficiencies were linked to diseases (scurvy, rickets etc.) - In modern day Western Society chronic diseases are associated with energy and sometimes nutrient excess (over nutrition)

Why do we eat?

- Hunger - Because of the time of day (habit) - To celebrate - Stress (can make us eat or not eat) - To be sociable/because someone else is eating - Due to the presence of food (particularly if it looks or smells good)

Bond types

- Hydrophobic interactions - These amino acids orient themselves towards the centre of the polypeptide to avoid the water - Hydrophilic interactions - These amino acids orient themselves outward to be close to the water - Disulphide bridges - The amino acid cysteine forms a bond with another cysteine through its R group (side chain) - Very strong - Hydrogen bonds - Polar "R" groups on the amino acids form bonds with other polar R groups - Ionic bonds - Oppositely charged R groups bond together

Synthesis of non-essential amino acids

- If a particular non-essential amino acid is not readily available, cells can make it from another amino acid or keto acid - Using a nitrogen source to synthesis non-essential amino acids - Cells can make non-essential amino acids from a keto acid and from a nitrogen source (e.g. ammonia) - Transamination to synthesise non-essential amino acids - The body can transfer amino groups (-NH2-) from an amino acid to a keto acid, forming a new non-essential amino acid and a new keto acid. Transamination requires coenzyme vitamin B6 - If an essential amino acid is missing, the body may breakdown proteins to obtain it

Choline - Potential vitamin candidate

- Important part of phospholipids in cell membranes and can be made in vivo from the amino acid methionine (meat, milk, liver, eggs, peanuts) - Synthesis alone cannot produce enough choline at all stages of life, so it must be obtained from foods (lecithin and any membrane material in the diet) at certain times - It is therefore termed conditionally essential and has an intake value of: - Men: 550 ug/day - Women: 450 mg/day

Change in rates of weight loss surgery over time

- In 2014-2015 there were 22100 non-emergency admissions and 600 emergency admissions for weight loss surgery - Who is having weight loss surgery? - Mainly middle aged women - Bariatric surgery provides clear advantages over non-surgical options - Greater weight loss - Better long-term survival

Surgery for severe obesity: gastric banding

- In gastric banding, the surgeon creates a small gastric pouch using an inflatable band placed near the top of the stomach. The band is tightened or loosened by adding or removing fluid via an access port placed under the skin - Limits the amount of food that may be eaten without discomfort - Altered flow of food through the GI tract - Patients may develop nutritional inadequacies e.g. absorption of nutrients may be reduced

Surgery for severe obesity: sleeve gastrectomy

- In sleeve gastrectomy, the surgeon removes 70-85% of the stomach and staples the remaining portions together to create a vertical tube-shaped stomach with limited capacity - Limits the amount of food that may be eaten without discomfort - Altered flow of food through the GI tract - Patients may develop nutritional inadequacies e.g. absorption of nutrients may be reduced

Action of bile

- In the stomach, the fat and watery GI juices tend to separate. The enzymes in the GI juices can't get at the fat - When fat enters the small intestine, the gallbladder secretes bile. Bile has an affinity for both fat and water so it can bring the fat into the water - Bile's emulsifying action converts large fat globules into small droplets that repel each other - After emulsification, more fat is exposed to the enzymes, making fat digestion moreefficient - Once fat particles are small enough, lipase enzymes can attack them and break off the fatty acids ready for absorption

Health risks of being underweight

- Inability to handle medical stresses - Menstrual irregularities and infertility - Pregnancy problems - Osteoporosis and bone fractures - An appropriate weight for an individual depends on many factors, including body fat distribution, health history and current state of health

Underweight

- Incidence of underweight and associated health problems are less prevalent than overweight and obesity problems - Cases of underweight are diverse - Energy demands may be great and foods are needed to support growth and physical activity - Eating disorders represent severe cases

Epidemiological studies

- Include; cross-sectional population studies, case-control studies and cohort studies (prospective and retrospective) - Cross sectional and cohort studies - Scientists observe how much and what kinds of foods a group of people eat and how healthy those people are - Case-control studies - researchers compare who do and do not have a given condition such as a disease, closely matching them in age, gender and other key variables so that differences in other factors will stand out

Aggressive treatments for obesity

- Individuals with clinically severe obesity and major medical problems may benefit from drugs or bariatric surgery - Drugs: - Phentermine - works by reducing food intake and possibly increasing EE - Orlistat - reduces fat absorption - Lorcaserin - increases satiety and decreases food intake - Surgery: - Can create short- and long-term problems - Limits food intake by reducing stomach capacity - Decreases hunger and appetite hormones - Alters GI microbiota - Still requires dietary compliance

Other signs of vitamin A deficiency - Deficiency disease is called hypovitaminosis A

- Infectious diseases - Vitamin A deficiency is associated with impaired immunity and susceptibility to infectious diseases (e.g. Measles) - Supplementation can help with life-threatening infections (e.g. Malaria, HIV) - Keratinisation and mucous secretion - In vitamin A deficiency, the epithelial cells secrete keratin (keratinisation) causing rough, lumpy and dry skin - Goblet cells also secrete less mucous, which disrupts normal digestion and absorption of nutrients - worsens malnutrition. It also weakness defence mechanisms of the respiratory tract and other tissues

Cellular respiration of Carbohydrates - Step 1: Glycolysis

- Ingested carbohydrates are all converted to the simple sugar molecule glucose - First stage in cellular respiration of glucose is the formation of pyruvate that involves a number of metabolic steps, each with their own enzyme - There are 11 steps involved in glycolysis each with its own enzyme - This process is called glycolysis and results in the formation of two pyruvate molecules from each glucose. This process yields a small amount of energy, so is not considered efficient - 2 ATP are used and 4 released giving a net energy yield of 2 ATP. 2NADH molecules are also produced which migrate to the mitochondria to yield further energy later - The process of glycolysis occurs in the cytoplasm where there is little oxygen, so the process is anaerobic

Important body electrolytes

- Inside the cell: Mostly potassium and phosphate - Outside the cell: Mostly magnesium and chloride

Water intake and balance - dehydration

- Intake from liquids, foods and metabolism equals losses from the kidneys, skin, lungs and faeces - Dehydration occurs when water output exceeds input due to an inadequate intake or excessive losses - 1-2% loss of body water weight results in thirst, fatigue, weakness, vague discomfort and loss of appetite - 3-4% loss of body water weight results in impaired physical performance, dry mouth, reduction in urine, flushed skin, apathy etc. - 5-6% loss of body water weight results in difficulty concentrating, headache, irritability, sleepiness, impaired temperature regulation and increased respiratory rate - 7-10% loss of body water weight results in dizziness, muscle spasms, loss of balance, delirium, exhaustion and collapse, followed by death if not treated quickly

What are some misconceptions people have about iron intake and absorption?

- Iron supplements are not as well absorbed as food - That there is no upper limit of iron consumption - There is no need to consume orange juice (Vitamin C) with an iron supplement as the supplement is already in ferrous form

How to spot a fad diet

- It has any of the following words featured in promotional material: fast blasting, fat melting or metabolism boosting - It rates carbohydrates as terrible - Villainising food - The first chapter includes the phrase: 'everything we've been told about nutrition is wrong' - It goes into too many descriptive details about bowel actions - It uses a lot of impressive before-and-after weight loss shots - An A-list Hollywood celebrity used it to either shed kilos for their latest buffed movie role or got their pre-baby body back 1 week after leaving the hospital - Short term for unachievable goals - The person promoting it has a PhD from a non-accredited, correspondence university - The phrase: 'endorsed by [credible and appropriately qualified nutrition professional] is not to be found anywhere' - The diet rules are so complex, that for convenience sake its easier to buy specially prepared food and supplements. Fortunately, the diet author sells these products on their website - Dr Oz endorses it

What is a 'healthy, balanced diet'?

- It is a diet that provides a person with an adequate amount of all the nutrients they need (no nutrient inadequacies) and helps to optimise their long-term health - Choose a variety of foods from each of the five food groups depicted in the Australian Guide to Healthy Eating

Food composition

- It is the composition of foods and beverages that determines how much energy they contain - A bomb calorimeter may be used to measure food energy - Direct measure of food's energy value (as heat is measured) - When food burns, the chemical bonds break - Carbons and hydrogens combine with oxygen to form CO2 and water - The amount of O2 consumed = an indirect measure of the amount of energy released - Direct calorimetry measures the heat energy released - Indirect calorimetry measures the amount of oxygen consumed and CO2 expelled - But - Human body is less efficient and can not completely metabolise all of the energy in food - Physiological fuel value is the difference between the number of kjs measured with calorimetry and the number of kjs that the body derives from a food

How to identify a fad diet or weight-loss scan

- It may be a fad diet or weight-loss scam if it: - Sounds too good to be true - Recommends using a single food consistently as the key to the program's success - Promises quick and easy weight loss with no effort - Eliminates an entire food group - Guarantees an unrealistic outcome in an unreasonable period (e.g. lose 5kgs in 2 days) - Bases evidence on its effectiveness on anecdotal stories

BMI and mortality

- J-shaped BMI and mortality curve - Both underweight and overweight are associated with increased risk of premature mortality

Protein energy malnutrition (PEM)

- Kwashiorkor (18 to 2 yeas of age) - Caloric protein malnutrition - Wasting of muscles (fat present) - Anorexia (loss of appetite) - Skin changes (flaky dermatosis) - Hair changes (colour loss) - Infection and Irritability - Oedema - feet and abdomen - Fluid balance is affected - Rapid onset - Ketatomalacia (eye disorder) - Organomegaly (liver fat accumulation) - Retention of subcutaneous fat - Involves sudden and recent deprivation of food, as a result of: - Protein deficiency or - Illness - Protein deficient but receive enough calories - Marasmus (6-18 months of age) - Muscle loss (Match stick arms) - Appetite is good - Reduced weight (severely wasted) - Apathy and anxiety - Subcutaneous fat loss and Saggy skin - Metabolic rate reduced (feels cold) - Undernutrition (prolonged) - Sepsis (could lead to death) - Involves severe deprivation or impaired absorption of: - Protein, - Energy, - Vitamins and - Minerals - Protein and caloric deficiency

The lymphatic system of the digestive system

- Large fatty acids and fat soluble vitamins are soluble in water and will not enter capillaries - Mucosal cells bundle these lipids into chylomicrons - Chylomicrons are released into the lacteals (lymphatic vessels) within the villi - Chylomicrons bypass the liver and enter the circulatory system in the right lymphatic duct and thoracic duct (near the heart) - Components of the lymphatic system: - Lymph - Lymphatic vessels - Lymphatic tissues and organs - Functions of the lymphatic system: - Drains excess intestinal fluid from the tissues - Transports chylomicrons from the GI tract to the bloodstream - Carries out specific immune responses (filters out waste products and foreign bodies, produces lymphocytes and antibodies)

Factors affecting vitamin D levels

- Latitude/season/air pollution - Vitamin D deficiency is higher during the winter months in some countries due to low sun exposure. Heavy clouds or air pollution block the UV rays needed for vitamin D synthesis - Age - The ability to produce activated vitamin D drops with age. At 65 years, the skin produces only 1/4 of that which is produced by someone in their 20s - Skin colour - People with darker skin typically have lower levels of vitamin D than lighter-skinned individuals - Weight - A BMI above 30 is associated with lower blood levels of vitamin D. Vitamin D is stored in fat, so in people with obesity, less of the vitamin circulates in the blood where its available for use by the body - Diet - Very few foods naturally contain vitamin D. In Australia, vitamin D fortification is mandated for margarines and is voluntary for low-fat milk, powdered milk, yoghurt and soy milk. Some cereals and beverages may also be fortified, but this varies by brand. So the amount of vitamin D you get from food depends on the food you eat and how much milk you drink - Breastfeeding and certain health conditions - People with conditions such as inflammatory bowel disease, liver disease or cystic fibrosis may have trouble absorbing vitamin D which can lead to deficiencies. Breastfeeding mothers and their infants may become vitamin D deficient

From Guidelines to Groceries

- Lean and very lean options of meats and meat alternatives should be chosen (this will limit hypercholesterolaemic fatty acids and ensure adequate long chain omega-3 fatty acids in the diet) - Choose fat-free and low-fat milks and milk products to lower total fat intake below 30%. However the specific fatty acids in diary foods are not rich in hypercholesteremic saturated fatty acids but rather shorter chain forms - Butter, cream and some cheeses (all low in water) however can be rich sources of dangerous saturated fatty acids - so limit their intake - Choose a wide variety of vegetables, fruits and wholegrain foods (these are low in hypercholesteraemic fatty acids and contain many MUFA and PUFA types) - Avoid invisible fat from baked and fried foods, fast foods, pastries, cakes, chocolate and biscuits (these often contain the dangerous forms of saturated fatty acids - particularly palm oil in processed foods) - Choose low-fat options from food products in general (to get your fat intake below 30% of energy)

Lean beef and blood cholesterol

- Lean red meat does not raise cholesterol - The main fat in lean meat is phospholipids from cell membranes which are rich in MUFA and PUFA and stearic acid (18:0). None of these are hypercholesterolaemic - Animal fat however does raise cholesterol - particularly LDL cholesterol levels - Adding MUFA and PUFA oils did raise cholesterol slightly but only the HDL component - The vegetarian diet was low in fat and saturated fat which is healthy, however although rich in alpha-linolenic acid (18:3n3), it lacked EPA and DHA and these levels in blood decreased. Eating grass fed lean meat or fish raised the blood levels of EPA and DHA

Proteins involved in appetite control, energy regulation and obesity development - Leptin

- Leptin - Leptin is a protein hormone produced by adipocytes - Involved in ensuring maintenance of adequate energy stores for survival - As adipocytes gain more triglyceride fat, they secrete more leptin - This travels to the brain (via bloodstream) - Acts on receptors in the hypothalamus to suppress appetite - The obesity gene ob codes for the protein leptin - Leptin release causes: - Suppressed food intake - Increased energy expenditure

Recommendations on fat intake

- Less than 30% of dietary energy should come from fat - Less than 10% of dietary energy should come from saturated fat - Replace saturated fats in the diet with MUFA and PUFA - Balance omega-3 and omega-6 PUFA intake (at present our diet is heavily weighted towards omega-6 type - rich in grains) - Longer chain forms of omega-3 fatty acids (EPA and DHA) are anti-inflammatory, reduce blood clotting (hence MI) and lower blood pressure - The longer chain omega-3 fatty acids come from animals only

Iron absorption levels

- Level of absorption efficiency varies between individuals and needs - E.g. in pregnancy and child growth >30% absorption - E.g. In GI tract disease <5% absorption

The 2013 Australian Dietary Guidelines - Guideline 3

- Limit intake of foods containing saturated fat, added salt, added sugars and alcohol - Limit intake of foods high in saturated fat such as biscuits, cakes, pastries, pies, processed meats, commercial burgers, pizza, fried foods, potato chips, crisps and other savoury snacks - Replace high fat foods which contain predominantly saturated fats such as butter, cream, cooking margarine, coconut and palm oil with foods which contain predominantly polyunsaturated and monounsaturated fats such as oils, spreads, nut butters/pastes and avocado - Low fat diets are not suitable for children under 2 years - Limit intake of foods and drinks containing added salt - Read levels to choose lower sodium options among similar foods - Do not add salt to foods in cooking or at the table - Limit intake of foods and drinks containing added sugars such as confectionary, sugar-sweetened soft drinks and cordials, fruit drinks, vitamin waters, energy and sports drinks - If you choose to drink alcohol, limit intake. For women who are pregnant, planning a pregnancy or breastfeeding, not drinking alcohol is the safest option

Omega-6 PUFAs

- Linoleic acid (18:2n-6) - Arachidonic acid (20:4n-6) - Only found in animals

Omega-3 PUFAs

- Linolenic acid (ALA) (18:3n-3) - Found in both plants and animals - Eicosapentaenoic acid (EPA) (20:5n-3) - Found in animals only - Docosahexaenoic acid (DHA) (22:6n-3) - Found in animals only

Types of polyunsaturated fatty acids

- Linolenic acid, an omega-3 fatty acid - 18:3n-3 - Linoleic acid, an omega-6 fatty acid - 18:2n-6

Transport of lipids

- Lipid substances are difficult to move around the body in the blood (mostly water) - Lipid transport is made possible by a group of particles known as lipoproteins - Chylomicrons - largest of the lipoproteins are made in the intestines after a meal and are rich in fat and sterols and fat soluble vitamins - VLDL (Very Low Density Lipoproteins) are composed primarily of triglycerides and are produced in the liver - LDL (Low Density Lipoproteins) are composed primarily of cholesterol and are derived from VLDL particles that have already distributed their TG load around the body - HDL (High Density Lipoproteins) are composed primarily of protein and scavenge excess cholesterol from around the body and return it to the liver for reuse or excretion as bile

Fats and oils

- Lipids can be fats or oils - Most fats come from animal sources and most oils come from vegetable sources - Most saturated lipids were thought to come from animal foods in our diet, however with lowering of fat in meat and use of tropical oils by the food industry, this is not the case - Palm oil and coconut oil are highly saturated and are semi-solid at room temperature - Saturated fatty acids have no double bonds and have higher melting points than MUFA and PUFA (hence tend to be solid at room temp) - Monounsaturated fatty acids (MUFA) have one double bond - Polyunsaturated fatty acids (PUFA) have more than one double bond, lower melting point and tend to be liquid at room temp

Fat metabolism

- Lipoprotein lipase (LPL) promotes fat storage in adipose and muscle cells - People who are obese have more LPL activity in their fat cells than lean people do Gender differences: - LPL is regulated by gender-specific hormones: - Oestrogen in women - Testosterone in men - In women, fat cells in the breasts, hips and thighs produce abundant LPL - stimulating fat deposit - In men, fat cells in the abdomen produce abundant LPL - increasing risk for developing central obesity

Criteria for Nutrition content claims and health claims

- Low fat - Criteria = No more than 3g of fat per 100g of solid food (or 1.5g per 100ml of liquid food) - Good source of dietary fibre - Criteria = A serving must contain at least 4g dietary fibre - Low in salt - Criteria = The food contains no more sodium than 120mg/100ml or 100g - Low in sugar - Criteria = The food contains no more sugar than 2.5g/100ml for liquid food or 5g/100g solid food

Magnesium food sources

- Magnesium is part of chlorophyll, therefore is rich in green leafy vegetables - Rich in some water supplies. May be an important contributor in some areas - Deficiency - Deficiencies are rare, but symptoms include: - Weakness and confusion - Convulsions in extreme deficiency - Bizarre muscle movements of the eye and face - Hallucinations - Difficulties swallowing - Growth failure in children - Develops from alcohol abuse, protein malnutrition, kidney disorders and prolonged vomiting and diarrhoea - Toxicity - Symptoms from non-food magnesium are diarrhoea, alkalosis and dehydration

Calcium Deficiency

- Main condition of deficiency is osteoporosis - bones degrade - No early warning signs or symptoms of osteoporosis, as blood calcium levels are usually normal due to calcium loss from bones maintain the constant blood level - Development of osteoporosis is usually due to poor calcium intake and/or absorption and poor bone building in the critical bone development period - From 30 years onward everyone loses bone mass with age and even with a high peak bone mass - There are rare cases where low blood calcium occurs, not due to poor intake but a metabolic defect

Factors effecting iron absorption

- Main determinant of iron absorption is its dietary form - Ferric form Fe3+ is poorly absorbed and is reduced to the ferrous form Fe2+ in the GI tract by vitamin C or another water-soluble antioxidant - Absorption of the protein bound haem iron is ~25% whereas non-haem is ~5% depending on dietary factors or body iron stores - The presence of factors that bind to non-haem iron, making it unavailable for absorption - E.g. phytates, oxalic acid, fibres, food EDTA, calcium, phosphorus (milk), tannic acid (wine), tea, coffee, nuts - The presence of factors such as vitamin C, meat, fish and poultry proteins that enhance the sensitivity to iron absorption, particularly non-haem iron - The bodies iron levels - Iron deficiency makes the body more efficient at absorbing both haem and non-haem iron from foods

Calcium balance (homeostasis)

- Maintenance of constant blood calcium is essential - Controlled by two hormones (Calcitonin and PTH) and vitamin D - Involves a complex set of processes based around storage in bones, removal as required and efficiency of: - Excretion in kidneys and - Absorption in GI tract - Blood calcium balance, controlled by: - Thyroid hormone (calcitonin) - Parathyroid hormone - Vitamin D - Through their effects on: - GI tract, - Kidneys, - Bones - Thyroid gland detects high blood Ca+ - Calcitonin secreted and increases osteoblasts activity to lower blood calcium - Parathyroid gland detects low blood calcium -PTH and Vitamin D raise blood calcium by decreasing osteoblast activity and release of bone calcium, increasing kidney reabsorption of calcium and increasing intestinal efficiency of calcium absorption

The major minerals

- Major minerals are those that exist in the body in quantities above 5g - These are: - Calcium - Potassium - Sodium - Chloride - Magnesium - Phosphorous (exists mainly in phosphate form or in phospholipids) - Sulphur (exists mainly in sulfate form or in proteins)

Zinc transport

- Major portion is transported in the blood by protein albumin - Albumin concentration is major determinant of zinc absorption - During pregnancy and starvation (PEM) there is a lower albumin levels - Hence lower zinc uptake

The stomach's secretions

- Major site of protein digestion - Gastric glands release HCl to create a low pH environment (pH~2) - The acidic environment functions to: - Denature proteins aiding in their overall digestion - Activates the enzyme (pepsin) involved in protein digestion - Kills harmful bacteria - The stomach epithelium contains a mucous membrane which prevents the acids from damaging the gastric lining

Protein synthesis

- Making a protein is called gene expression - Synthesis of protein is determined by genetic information (DNA) - A messenger RNA (mRNA) copied from DNA provides the instruction of which amino acid to incorporate at which position for the synthesis of a specific protein - Transfer RNA (tRNA) lines up amino acids and brings them to the messenger RNA - The ribosomes move along the mRNA and read the code and joined specified amino acids together in the order dictated by the code to make a specific protein molecule - Ribosome = a protein making factory

Nutrition Status Assessment

- Malnutrition includes both over-nutrition and under-nutrition - Over-nutrition is due to excess energy and or fat intake. Common in Western lifestyle diseases e.g. diabetes, cardiovascular disease - Under-nutrition often exists as protein energy malnutrition (PEM) resulting in weight loss, infection, muscle wasting or a specific nutrient deficiency

Health of the GI tract

- Many factors influence health and regulation of the GI tract - Age, diseases and diet can affect function - Estimated 10 trillion (10^12) microbes (bacteria, viruses, protozoa and other microorganisms) live in the GI tract - Flora and microflora assist digesting some fibre and protein - Prebiotics are bacteria found in the foods such as yoghurt, that can be beneficial to health - Prebiotics are certain chemical compounds, not absorbed but used as food by the intestinal bacteria

Setting the RDI for a nutrient

- Many studies looked at as much data is compiled as possible - RDI is two standard deviations above EAR (estimated average requirement) - If RDI = EAR half of the population wouldn't get enough of that nutrient - An RDI 2 SDs above EAR covers 98% of the population - Theres normally a large difference between RDI and UL - For EER (Estimated energy requirement), RDI = Mean

Muscular (mechanical) digestion

- Mastication (chewing) - Peristalsis - Stomach action - Segmentation - Sphincter contractions

Age and bone calcium

- Maximising bone mass - Children and adolescents need to consume enough calcium and vitamin D to create denser bones - With a higher initial bone mass, the normal losses of bone density that occur with age will have less detrimental effects - Minimising bone loss - Ensure adequate intakes of vitamin D and calcium are consumed - Adequate physical activity - Note: hormonal changes can increase calcium losses

Zinc absorption

- Mechanism is similar to iron but intestinal mucosa cells can take zinc back from blood as well as deliver it - Binding protein is called metallothionein or zinc binding protein (ZBP) - ZBP binds and stores dietary zinc - Major portion of zinc is used in pancreas for production of digestive enzymes - Bodies zinc stores are adjusted by reabsorption or non-absorption in the GI tract - Bioavailability is 4 times higher from meat than fibre rich cereals - Fibre and phytates in cereals bind zinc - Casein in cows milk binds zinc, human milk doesn't

Magnesium Nutrient Reference values

- Men (19-30) RDI = 400mg/day - Men (>30) RDI = 420 mg/day - Women (19-30) RDI = 310 mg/day - Women (>30) RDI = 320mg/day - Women (pregnant) RDI = 320-400 mg/day - Women (lactating) RDI = 310-360 mg.day - Men and women UL = 350mg from supplements

Nutrient Reference Values for Iron

- Men (>19) RDI = 8 mg/day - Women (19-50) RDI = 18 mg/day - Women (>50) RDI = 8 mg/day - Women (pregnant) RDI = 27 mg/day - Women (lactating) RDI = 9 mg/day - Men and Women UL = 45 mg/day

Male vs Female body composition and fat distribution

- Men have more muscle mass - Females have more fat mass - Abdominal fat is more common in men than women - Men tend to have apple-like 'androidal' obesity - Young and middle-aged women tend to have pear-like 'gynoidal' obesity - After menopause women's fat distribution becomes more androidal

What is energy metabolism?

- Metabolism refers to all chemical reactions occurring in living cells - Where the body uses energy from the food we eat, it is called specifically "energy metabolism" or "cellular respiration"

Hydrolysis during digestion

- Micronutrients require little or no digestive preparation - Macronutrients need to be broken down into basic units to allow absorption - Carbohydrates -(enzyme)> glucose + other monosaccharides - Proteins -(enzyme)> amino acids - Triglycerides -(enzyme)> glycerol + fatty acids

Vitamin D summary

- Mineralisation of bones (raises blood calcium and phosphorus by increasing absorption from digestive tract withdrawing calcium from bones and stimulating retention by kidneys) - Deficiency symptoms = rickets, osteomalacia - Toxicity symptoms = calcium imbalance (calcification of soft tissues and formation of stones) - Significant sources = synthesised n the body with the help of sunshine; fortified margarine

Non-energy yielding nutrients

- Minerals - are chemical elements that cannot be changed, as they enter and leave the body in the same form, hence contribute no energy - Water - Vitamins - These support enzyme function, contain C, H, O, N and other elements but contribute no energy

Carbohydrate absorption

- Monosaccharides are absorbed at different rates - Glucose and galactose transverse intestinal cells by active transport - Fructose is absorbed by facilitated diffusion which slows its entry into the bloodstream - Fructose and galactose are converted to glucose in the liver

Naming of fatty acids

- More than one naming system - Systematic chemical naming system used by chemists (number from alpha (carboxylic acid) end) - Biochemists use a different naming system based on physiological aspects of the fatty acid (number from omega (methyl) end) - Either way the naming is based on the length of the chain in terms of carbon number and the number of double bonds and their position. The notation system used in biochemistry needs to be understood - E.g. 20:4n-6 - Means 20 carbon chain, 4 double bonds, the first on carbon 6 from the omega (methyl) end - A third naming system involves use of trivial (historical or common) names not based on any scientific principle

Calcium (Ca2+)

- Most abundant mineral in the body, mainly in bones and teeth (99%) - Bones are a calcium store, releasing calcium into the blood as blood levels fall, blood calcium levels are kept constant while bones are constantly formed and dissolved - Bone and blood calcium are kept in balance with a system of hormones and vitamin D - Bone formation involves hydroxyapatite forming on a collagen protein matrix - Approx. 1% of body calcium circulates as Ca2+ ions in the blood - A blood test for calcium status is useless as the blood level is kept constant Blood calcium is kept constant by balancing intake and excretion and drawing on bone calcium when required - Other important roles of calcium - Regulation of muscle contraction - Blood clotting Transmission of nerve impulses - Hormone secretion - Activation of some enzyme reactions - Cofactor for calmodulin (membrane protein which conveys messages to cell interior) - Low levels of calcium are associated with elevated BP

Trans fatty acids

- Most mono and poly unsaturated fatty acids in foods are normally in a cis configuration - A few natural trans forms occur in some animal foods and milk, particularly in human breast milk (CLA and vaccenic acid) and have never been shown to cause a health issue - However some fatty acids are changed from cis to trans configuration during hydrogenation of plant oils to make solid margarine - Mainly elaidic acid (18:1 trans-9) is formed - Acts like some saturated fatty acids in the body - increasing blood cholesterol levels - Its heart disease connection is being researched and results implicate 18:1 trans-9 (but not all trans fatty acids) as being involved in CVD - Conjugated linoleic acid and vaccenic acid are naturally occurring trans fatty acids that may be beneficial to health (no issues ever found) - Oleic acid 18:1: - The cis form is beneficial to out health - Humans consume mostly the cis form from nature - The trans form creates health problems - Humans also consume some trans form from the partial hydrogenation in making margarines and shortenings used in the food industry

Dose levels and effects: A common myth

- Most people believe that if a nutrient is good for your health the more you eat the healthier you should be - In reality the benefit normally plateaus once adequate intake is reached e.g. Vitamin C - In certain cases once adequate intake is surpassed excess intake can have a toxic effect e.g. Vitamin A

Protein structures: enzymes

- Most protein types are enzymes, though a few are also structural or hormones - The enzyme proteins have specific shapes that make them suited to holding and reacting specific molecules in the cells - To do this though they generally require the help of a coenzyme (B group vitamin) - E.g. Alpha-amylase, Polyphenol oxidase enzyme

Varying pH of the GI tract

- Mouth (neutral pH): Saliva enzymes don't work in the stomach due to the low pH - Stomach (low pH): HCl acid is released in when food is detected in the stomach - Small intestine (neutral pH) - Pancreatic juice contains sodium bicarbonate, which is alkaline and this helps to neutralise the acidic chyme that enters the duodenum. From this point on chyme remains at a neutral or slightly alkaline pH - Bile is slightly alkaline

Digestion and absorption of lipids throughout the GI tract

- Mouth and salivary glands - Some hard fats begin to melt as they reach body temperature. The sublingual salivary gland in the base of the tongue secretes lingual lipase - Stomach - The acid-stable lingual lipase initiates lipid digestion by hydrolysing one bond of triglycerides to produce diglycerides and fatty acids. The degree of hydrolysis by lingual lipase is slight for most fats but may be appreciable for milk fats. The stomach's churning action mixes fat with water and acid. A gastric lipase accesses and hydrolyses (only a very small amount of) fat - Small intestine - Bile flows in from the gallbladder (via the common bile duct) - Bile emulsifies fat - Pancreatic lipase flows in from the pancreas (via the pancreatic duct) - Pancreatic (and intestinal) lipase hydrolyses the TG into monoglycerides, glycerol and fatty acids - Large intestine - Some fat and cholesterol, trapped in fibre, enter in faeces

Lipid usage and storage - Energy from storage fat on the body

- Much larger energy store than liver and muscle glycogen, suppling approximately 60% of the bodies energy at rest - Hormone sensitive lipases in adipose cells hydrolyse TG when energy is required. Glycerol and fatty acids formed are transported back into the blood (to form lipoproteins) to be circulated to cells requiring energy - Fatty acids are converted to acetyl-CoA then oxidised to carbon dioxide and water releasing bond energy in the mitochondria of cells through the TCA cycle/ETC - TCA cycle = Tricarboxylic acid cycle (Krebs cycle) - ETC = Electron Transport Chain

Cell specialisation

- Mucosal cells at different sites of the small intestine are specialised to absorb certain nutrients - Those nutrients that are quickly digested are generally absorbed higher in the small intestine - Very little absorption occurs in the large intestine (colon)

How could an individual improve dietary calcium intake if intakes are less than recommended?

- Omnivores - dairy foods: milk, yoghurt, cheese, soy products, nuts, leafy greens - Lactose intolerant individuals - can eat leafy green vegetables as well as calcium fortified foods eg. oat milk, orange juice, soy products, also sardines are a source of calcium - Vegans - can eat leafy green vegetables as well as calcium fortified foods eg. oat milk, orange juice, tofu, or have supplements

Nutrition Assessment - The population

- National nutrition surveys: - Most western countries have a periodic national diet survey - Australia has a more ad hoc approach (depending on what government is in power) - There have been four national surveys in the last 50 years: - National Dietary Survey of Adults - 1983 - National Dietary Survey of Children - 1985 - National Nutrition Survey - 1995 - Australian Health Survey - 2012 - National nutrition monitoring programs use survey research to collect data on foods people eat and people's health status - Data collected is used for development of nutrition policy, food assistance programs and food supply regulation - National trends show an increased intake of fast food, increased portion sizes and an increased consumption of energy-dense foods and drinks. This intake is associated with an increased risk for overweight and obesity and other chronic conditions

Beware of Nutrition Quackery. There are lots of unsupported claims such as:

- Natural - Any products that is strong enough to be effective is strong enough to cause side effects - Quick and easy fixes - even proven treatments take time to be effective - Satisfaction guaranteed - Marketers may make generous promises but consumers won't be able to collect on them - One product does it all - No one product can possibly treat such a diverse array of conditions - Time tested - such findings would be widely publicised and accepted by health professionals - Paranoid accusations - Personal testimonials - hearsay is the weakest form of evidence - Meaningless medical jargon - phoney terms hide the lack of scientific proof Beware of industry (and individuals) self promotion, including website advertising of products (that often do not seem like advertising)

Natural trans fats vs saturated fats

- Natural trans fats, which include conjugated linoleic acid (CLA) and vaccenic acid (18:1 trans-11) are not harmful - Virtually all of the saturated fat in palm oil is palmitic acid (16:0), one of the most hypercholesterolemic fatty acids, whereas in butter, cocoa butter, lard and tallow the dominant saturated fatty acid is stearic acid, which has no effect on blood cholesterol

What are vitamins?

- Necessary compounds for growth and cellular metabolism - Only necessary in trace amounts - Organic compounds - Some can be made in vivo in small amounts (still need to consume them) - Niacin, Vitamin D, Vitamin K and Vitamin B12 (but not absorbed) - Term comes from: 'Vital amine', as all the original compounds thought to be needed in the diet were amines (incorrect)

Energy balance

- Neutral energy balance - Energy consumed = energy expended - Body weight is stable - Positive energy balance - Energy consumed > energy expended - Weight increases - Negative energy balance - Energy consumed < energy expended - Weight decreases

Vitamin A deficiency and vision

- Night blindness - First sign of vitamin A deficiency - Retina does not receive adequate retinal to replace losses (from conversation to retinoic acid) - Blindness (xerophthalmia) - Xerophthalmia is a major cause of childhood blindness, causing more than half a million to lose their sight each year - Is the failure to see at all - Caused by lack of vitamin A in the cornea

Is losing weight always beneficial to health?

- No - E.g. for a woman with a BMI of 26. If she follows a starvation diet or used diet pills she is likely to end up less healthy than before - But for people who are overweight or obese with risk factors it could be beneficial - E.g. for people with: - Heart disease - Type 2 diabetes - Sleep apnoea - 5-10% weight loss can produce clinically significant improvements in risk factors such as blood cholesterol, insulin sensitivity and blood pressure

Water intake and balance

- Normal water intake and loss levels for the average person per day, approx. 500ml is a minimum urinary daily excretion level to remove dissolved waste materials - Intake: - Liquids 550-1500ml - Foods 700-1000ml - Metabolic water 200-300ml - Total = 1450-2800ml - Loss - Kidneys (urine) 500-1400ml - Skin (sweat) 450-900ml - Lungs (breath) 350ml - GI tract (faeces) 150ml - Total = 1450-2800ml

Nutrient reference values (NRV)

- Nutrient reference values apply to healthy people - Recommendations are not minimum requirements and can be adjusted for individuals by dietitians - Are achieved by consuming a variety of foods - Apply to average daily intakes - Each NRV category serves a unique purpose, either nutritional assessment of individuals or populations - EARs are for groups/populations - RDI/Ais are for individuals

The science of nutrition

- Nutrients provide the physical and metabolic basis for nearly all that we are and all that we do - The science of nutrition is the study of the nutrients and other substances in foods and the body's handling of them - Types of studies to expand nutrition knowledge include: - Epidemiological studies - cross-sectional, case-control and cohort designs - Lab-based studies - animal studies and lab-based in vitro studies - Human intervention or clinical trials

Nutrition Information and Misinformation

- Nutrition on the net - Internet information can be published by anyone - May be high-quality information: National library of medicine's pubmed - May be misleading, incomplete and inaccurate - Nutrition in the news - Can be misleading and contradictory due to many factors - May report scientific findings prematurely or inaccurately - Note: Journalists have little or no scientific training so cannot put results of new studies into context

Energy calculations

- Nutritionists and dieticians consider a person's diet in terms of what contribution to energy each macronutrient makes, not the actual absolute gram amount of each - g/day intake x kj/g = kj/day

Health risks associated with body weight and body fat

- Obesity-related diseases include: - Cardiovascular disease - Type 2 diabetes (due to insulin resistance) - Inflammation and the metabolic syndrome - Cancer - Obesity can also increase the risk of: - Hypertension - Sleep apnoea - Osteoarthritis - Gall bladder disease - Kidney stones - Complications in pregnancy and surgery

Sphincters in the GI tract:

- Oesophageal sphincters - Pyloric sphincter - Ileocecal valve - Two sphincters of the anus (extra safety)

Risk factors for osteoporosis

- Older age - Low BMI - Cigarette smoking - Excess alcohol consumption - Sedentary lifestyle

Lactose intolerance

- Only a small percent (~30%) of people retain enough lactase to digest and absorb lactose in adult life - Lactase activity declines with age or damaged intestinal villi - Symptoms include bloating, abdominal discomfort and diarrhoea - Up to 6g of lactose (1/2 cup of milk) can be consumed without symptoms - Management can include: - Increasing consumption of milk products gradually - Mixing dairy with other foods - Spreading diary intake throughout the day - Use of acidophilus milk, yoghurt or lactose-free products - Use of enzymes

Vitamin C

- Only non-B group vitamin that is water soluble - It is a 6 carbon compound, structurally similar to glucose - Has 2 active but interchangeable forms, the reduced form (ascorbic acid) and the oxidised form (dehydroascorbic acid) - Has a number of functions, firstly as an antioxidant and also in collagen formation, hormone production and as a coenzyme in some reactions

Fatty acids

- Organic acids containing a "fatty" chain of CH2 groups that are highly non-polar (i..e hyrophobic) - Characteristics: - Only contain C, H, O - Terminal groups are (methyl) -CH3 and (carboxylic acid) -COOH - Chains consist of multiple -CH2 units, except where double bonds are located and the chain units have one less H atom (CH not CH2) - Naturally occurring fatty acids have an even numbered carbon chain and generally range from 4-26 carbons

Vitamin B background

- Other substances once thought to be vitamins were given numbers in the B-vitamin numbering scheme, but were subsequently discovered to be either not essential for life or manufactured by the body, thus not meeting the two essential qualifiers for a vitamin - Some of the better known candidates are listed below, but sometimes several compounds at different times were designated with B vitamin numbers and then dropped and replaced by other compounds. In the future new ones may be added - Vitamin B4 - can refer to the distinct chemicals choline, adenine or carnitine - Vitamin B8 - refers to adenosine monophosphate (AMP) or to inositol - Vitamin B10 - para-aminobenzoic acid (PABA), a chemical component of the folate molecule produced by some plants and bacteria - Vitamin B11 - pteryl-hepta-glutamic acid

The rationale that gym trainers have used to convince themselves that protein supplements and a high-protein diet might increase their muscle mass is false. Why?

- Our body requires proteins as well as other nutrients like carbohydrates and fat. Eating a diet too rich in protein would mean consuming less calories than required. Our body would use stored muscle for energy thus reducing muscle mass. - Any protein you eat on top of what your body needs will either be excreted from your body as waste, or stored as weight gain.

Environmental causes of obesity

- Overeating - Increased availability of convenient food - Energy-dense foods - Large portions - Accessibility - If food is easily accessible it is harder to resist - Socialising - Visual cues from companions - Extended duration of meals - Ambiance can affect meal duration - Distractions - Interfere with internal controls to stop eating and extend duration of eating - Variety - Increased food options can increase oral intake - Serving containers - Large plates and bowls can increase serving sizes - Social inequalities - The highest rate of obesity is observed among groups with the lowest levels of education and income - Physical inactivity - Life requires little exertion - Modern technology has replaced physical activity

Fatty acid composition of fats and oils

- Palm oil and coconut oil are major saturated fatty acid sources - Some of the most saturated fatty acid-rich food sources are plants - The biggest contributor to dietary saturated fat intake is palm oil in processed foods

Vitamin B5 (Pantothenic acid) Function

- Pantothenic acid is involved in over 100 metabolic steps, mostly in its coenzyme form (coenzyme A) - Processes include: - Energy metabolism - Lipid synthesis - Neurotransmitter synthesis - Steroid hormone synthesis - Haemoglobin synthesis - In energy metabolism pantothenic acid is critical as a component of acetyl-CoA, as the cross-roads compound leading into energy release from the TCA cycle and electron transport chain or to fat production

Protein digestion in the stomach

- Partial breakdown (hydrolysis) of proteins begins in the stomach - Hydrochloric acid denatures proteins so that digestive enzymes can attack the peptide bonds - Hydrochloric acid activates the digestive enzyme, pepsin, from its inactive form (pepsinogen) - Prevents auto-digestion - Pepsin cleaves large polypeptides into smaller polypeptides and some amino acids

What is peak bone mass?

- Peak bone mass is the maximum amount of bone a person has during their life - It typically occurs in the early 20s in females and late 20s in males

Peer review

- Peer reviewed literature i.e. scientific journals - articles checked by other scientists to weed out poor experiments - Non-peer reviewed i.e. books, magazines, newspaper articles, websites, social media. There can be great variability in content and accuracy - Articles appearing in scientific journals have been checked by other experts in the field in regard to the experimental design and results - Was there a control and experimental group? - Was the sample size sufficient? - Was a placebo used? - Was the experiment double blinded? - Is there connection to existing scientific knowledge? - Is existing knowledge cited and referenced? - Do the conclusions drawn follow logically and objectively?

Dangerous interventions to lose weight

- People are so keen to lose weight, they sometimes risk lots of money and adverse health outcomes - Fat diets - Sound good but are often nutritionally poor and hazardous to health - Weight-loss products - Ephedrine-containing (amphetamine-like substance) products inhibit serotonin and suppress appetite - Supplements containing ephedra have been banned by the TGA due to their potential health risks - Herbal laxatives do not prevent absorption - Current laws do not require safety tests and effectiveness tests for these products

Diet planning principles - Energy (kJ) control

- People of a healthy weight need to consume a diet that keeps them in energy balance - Ideally energy intake = energy expenditure - Body weight is stable when energy consumed = energy expenditure

Iron Absorption enhancers

- People who have an iron deficiency become more efficient at absorbing both haem and non-haem iron from foods - There are factors that can enhance the sensitivity to iron absorption, particularly non-haem iron, such as vitamin C and meat, fish, poultry proteins

Vitamin D recommendations

- People who live in northern/southern regions of the world, are older than 65 years or live in smoggy areas are advised to consume foods with vitamin D - Adequate intake: - 5 μg/day for adults aged 19-50 - 10 μg/day for adults aged 51-70 - 15 μg/day for adults aged 70+ - Primary food sources include: - Fortified milk, butter and margarine - Egg yolks and liver - Fatty fish and their oils - Vegans likely to require supplements

Perceptions and prejudices of overweight and obese people

- People with a healthy weight sometimes assume that every obese person can achieve a healthy weight and should pursue that goal - Most obese people do not successfully lose weight and maintain the loss - Obese people are sometimes stereotyped as lazy and lacking self control - There is sometimes discrimination in employment, at school and in social situations - Many weight loss programs assume it is easy to lose weight - Then overweight people blame themselves for failure of weight loss when the program has failed - People can decide whether weight loss might be beneficial by considering their health status, but also their motivation - It is important to remember the potentially devastating psychological effects of obesity

Are plant 'milks' nutritionally equivalent?

- Perceived as healthy - Large variation in nutritional profile - Most are low in protein, minerals and vitamins - Unknown nutrient bioavailability

Food choices can significantly affect our health and are influenced by multiple factors, including;

- Personal preferences for flavours - Genetics - Habit - Cultural or religious beliefs and traditions - Social interactions, such as special events, customs and holidays where food is involved - Food availability, convenience and the economy - Personal values related to the ethical treatment of animals and the planet

Vitamin K sources and types

- Phylloquinone (vitamin K1) - Is the main dietary form of vitamin K - Found primarily in green leafy vegetables - Menaquinone (vitamin K2) - Are predominantly of bacterial origin - Are present in modest amounts in various animal-based and fermented foods - Half of the vitamin K needed in our body comes from the bacteria within our guts

Factors affecting energy expenditure (EE)

- Physical activity (voluntary movement) - Most variable component of EE - Significant in weight loss and weight gain - Duration, frequency and intensity influence energy expenditure - Thermic effect of food (TEF) - ~10% of total energy intake - Digestion and absorption require energy (e.g. for contractions, making and secreting digestive juices, active transport during absorption) - Produces heat - Greater for high protein foods than high fat foods - Adaptive thermogenesis - Adjustment in energy expenditure related to environmental changes - E.g. when the body has to adapt to extreme cold, overfeeding, starvation, trauma or other forms of stress - Physiological adjustments are made (e.g. building tissue, making enzymes) - they require energy - However, as adaptive thermogenesis is so variable, it is in calculations of energy requirements

What are the differences in protein quality between animal and plant based sources?

- Plant proteins are 70-90% absorbed while animal proteins are 90-99% absorbed - Animal foods contain all the essential amino acids and are generally 'high quality' (complete proteins), while only a few plant foods contain complete proteins (tofu and quinoa), since plant foods are diverse in content and tend to be limiting in one or more essential amino acids (incomplete proteins)

Vitamin E sources

- Polyunsaturated plant oils such as margarine, salad dressings and shortenings - Wheatgum - Wholegrain foods - Liver and egg yolks - Nuts and seeds - Green, leafy vegetables - As vitamin E is easily destroyed by heat and oxygen, fresh or minimally processed foods are preferred

Potassium (K+)

- Potassium is a cation, like sodium (but predominates inside cells) - It is essential for fluid and electrolyte balance and maintaining cell integrity - With sodium and calcium it is involved in nerve impulse transmission, muscle cell contraction and heart beat regulation - Food sources - Potassium exists in all intact animal and plant cells - Fruit and vegetables contain a high potassium: sodium balance - Broccoli, carrots, tomato juice, strawberries, squash, artichoke are all high in potassium - Processing of foods leads to cell breakdown and loss of potassium - Our hunter-gatherer ancestors consumed an estimated 10500mg K/day compared to the current US intake of 2500mg/day - Roles of Potassium in the body - Maintains normal fluid and electrolyte balance - Facilitates many reactions - Supports cell integrity - Assists in nerve impulse transmission and muscle contractions - Maintains the heart beat - Nutrient Reference Values - Men AI = 3800 mg/day - Women/Women (pregnant) AI = 2800 mg/day - Women (lactating) AI = 3200 mg/day - Men and women Ul = not set - Most people fail to meet these levels - Deficiency - Symptoms include muscular weakness, paralysis, confusion, increased blood pressure, salt sensitivity, kidney stones and bone turnover - Later signs include irregular heartbeats, muscle weakness and glucose intolerance - Toxicity - Results from supplements or overconsumption of potassium salts or medical conditions - Symptoms include muscular weakness and vomiting - If given into a vein, potassium can cause the heart to stop

Physical activity guidelines for preventing weight gain and promoting weight loss

- Preventing weight gain - Physical activity of 150-250 minutes/week with an energy equivalent of 5000-8500 kj/week will prevent weight gain greater than 3% in most adults - Promoting weight loss - Physical activity <150 minutes/week promotes minimal weight loss - Physical activity >150 minutes/week results in modest weight loss of approx. 2-3kg - Physical activity >225-420 minutes/week results in 5-7.5kg weight loss and a dose-response exists

The structure of proteins

- Primary protein structure - Sequence of a chain of amino acids - Secondary protein structure - Local folding of the polypeptide chain into beta helices or alpha sheets - Determined by weak electrostatic attractions of hydrogen bonds - Tertiary protein structure - Three-dimensional folding pattern of a protein due to side-chain interactions - Polypeptide chain twists and folds; side groups attached to one another or are repelled by or attracted to the surrounding fluids = intricate shape - Disulphide bridges help determine the tertiary structure (e.g. insulin) - Quaternary protein structure - Protein consisting of more than one amino acid chain - Interactions between multiple polypeptides e.g. haemoglobin

Vitamin B2 (Riboflavin) Food sources

- Primary sources are diary products, meat, leafy green vegetables, cereals, eggs, liver and fortified cornflakes - Cornflakes, Broccoli. Milk, Plain yoghurt, Egg, Liver, Mushrooms - Toxicity symptoms - None known - Nutrient reference vales for Riboflavin are: - RDI = 1.3 mg/day for men (19-70 yrs) - RDI = 1.6 mg/day for men (>70 yrs) - RDI = 1.1 mg/day for women (19-70 yrs) - RDI = 1.3 mg/day for women (>70 yrs) - RDI = 1.4 mg/day for women (pregnant) - RDI = 1.6 mg/day for women (lactating)

Protein digestion in the small intestine

- Proteases are stored as inactive proenzymes. The pancreas stores trypsin as trypsinogen and chymotrypsin and chymotrypsin - Once chyme enters the small intestine enteropeptidases converts trypsinogen to the active form trypsin - Trypsin then converts: - Chymotrypsinogen to chymotrypsin - Procarboxypeptidases to carboxypeptidase - Pancreatic proteases break down proteins into oligo, tri- and di-peptides - These are further broken down to single amino acids by intestinal peptidases

Polypeptide, peptide and protein

- Protein is generally used to refer to the complete biological molecule in a stable conformation, whereas peptide is generally reserved for a short amino acid chain often lacking a stable 3D structure - However, the boundary between the two is not well defined and usually lies near 20-30 amino acids - Polypeptide can refer to any single linear chain of amino acids, usually regardless of length, but often implies an absence of a defined conformation

Protein quality

- Protein quality of the diet dictates health - A high quality diet is one which supplies all essential amino acids in the right proportion - The two factors which determine the protein quality of a food are: - How well the essential amino acid content matches the requirement of the human body - How easily the protein is digested and absorbed into the body for utilisation - Not all protein sources are digested equally -Animal proteins are 90-99% absorbed -Plant proteins are 70-90% absorbed -Soy and legumes are 90% absorbed -Other foods consumed at the same time can affect digestibility - Dietary protein must provide essential amino acids. If one of the 9 essential amino acids is not supplied in the diet, the body breaks down existing proteins to obtain the needed amino acid to make the required protein or simply stop making the new protein - Animal foods contain all the essential amino acids and are generally 'high quality' (complete proteins). A few plant foods are complete proteins i.e. tofu and quinoa - Limiting amino acids are those essential amino acids that are supplied in less than the amount needed to support protein synthesis. The four most likely amino acids to be limiting are; lysine, methionine, threonine and tryptophan - Plant foods are diverse in content and tend to be limiting in one or more essential amino acids (incomplete protein) - The best guarantee of amino acid adequacy is to eat foods containing high-quality proteins or mixtures of foods containing complementary proteins that can each supply the amino acids missing in the other

Protein energy malnutrition

- Protein-energy malnutrition is a form of malnutrition that is defined as a range of pathological symptoms arising from lack of dietary protein and/or energy in varying proportions - One in four children worldwide is affected - Children who are excessively thin for their height may be suffering acute PEM (recent severe food deprivation) - Children who are short for their age may have experienced chronic PEM (long term food deprivation) - PEM is most prevalent in Africa and Central and South America and parts of South and Southeast Asia - It is also common in children of lower socioeconomic groups and people with eating disorders (or faddish diets) in developed countries - There are two forms of protein energy malnutrition (PEM) - Marasmus (wasting) - Kwashiorkor (oedema)

Protein - Acid-base regulators

- Proteins act as acid-base "buffers" - They take up or release H+ from body fluids - Under acidic conditions (low pH), there are many H+ ions in the fluid. Protein absorbs the H+ making less H+ available in the fluid and pH rises (i.e. less acidic). Under alkaline conditions, pH is high (i.e. few H+), so proteins release H+ to lower pH (i.e. more acidic) - Prevents acidosis and alkalosis which can be life-threatening

Protein metabolism

- Proteins can yield energy as well as being used to build human protein in cells - If consistent amino acids from dietary protein are used to make human protons, then no breakdown of amino acids is necessary - If amino acids are to be used for energy they must be broken down first and the nitrogen group removed - The cleavage of amino (nitrogen) group from amino acids creates a problem for the body, in that the ammonia formed is toxic and must be efficiently removed from the body - The liver converts the ammonia into urea (NH3) and it is removed from the body in urine

Proteins and amino acids

- Proteins in the body are made from 20 different amino acids, 9 of which are essential - Each amino acid has an amino group, an acid group, a hydrogen atom and a side group - It is the side group that makes each amino acid unique - The sequence of amino acids in each protein determines its unique shape and function - Amino acids are composed of the elements Carbon, Hydrogen, Oxygen and Nitrogen - Two amino acids also contain Sulfur, which is critical for protein structure - Methionine and Cysteine

Food labels

- Provide consumers with information needed to select healthful foods - Contain relevant information presented in a standardised, easy-to-read format

Public health programs to promote healthy weight

- Public health programs have been suggested to: - Shift the supply and marketing of food to healthier choices - Regulate levels of unhealthy nutrients - Implement health programs in schools, communities and workplaces - Develop targeted approaches - Establish a national prevention agency

How can an individual increase their dietary fibre intake to reach recommendations?

- Rather than eating more foods can easily be swapped for choices with higher dietary fibre content. - E.g. Wholegrain cereal products, fruit, vegetables, nuts and legumes, beans

Tertiary and quaternary protein structure of insulin

- Relatively small protein that consists of 51 amino acids in two short polypeptide chains - Two disulphide bridges link the two chains - A third bridge spans a section within the short chain - Insulin is a Globular hormone protein

Impact of nutrition on decision making

- Research has linked carbohydrates to mood and decision making - People who had a rich-carbohydrate meal were more likely to implement social punishment when playing the "ultimatum game" than those who ate high-protein breakfasts - Scientists speculate this may be caused by dopamine levels, which are higher after eating carbohydrates

Gastrointestinal microbiome

- Research is trying to understand how composition of the gut relates to health, it's been linked to: - Gut conditions (IBS, clostridium difficile) - Obesity - Metabolic disease - Markers of inflammation - Markers of CVD (e.g. BP and cholesterol) - Diet is the modifiable factor with the greatest impact on gut microbiome - Plant-based diets appear to be beneficial - Bacteria produces several vitamins (biotin, folate, pantothenic acid, riboflavin, thaimin and vitamins B6, B12 and K)

Vitamin A: retinoids and carotenoids

- Retinoids (performed vitamin A) - Retinol - Retinal - Retinoic acid - Supplied by foods from animals e.g. fish, diary, eggs, liver - This active form of vitamin A is absorbed more efficiently than the carotenoids - They have 6x the biological activity of an equivalent dose of carotenoids - Carotenoids (precursor vitamin A or pro-vitamin A) - β-carotene - α-carotene - β-cryptoxanthin - Converted to retinol in the intestines - Suppled by foods from plants e.g. fruits and vegetables (especially orange and dark-green ones) - Absorption of carotenoids is far less efficient than absorption of retinoids

Accessory organs and their secretions during digestion

- Salivary glands - Secretes saliva into the mouth - Fluid eases swallowing; salivary enzyme breaks down some carbohydrates - Gastric glands - Secretes gastric juice into the stomach - Fluid mixes with bolus; hydrochloric acid uncoils proteins; enzymes break down proteins; mucous protects the stomach cells - Pancreas - Secretes pancreatic juice into the small intestine - Bicarbonate neutralises acidic gastric juices; pancreatic enzymes break down carbohydrates, fats and proteins - Liver - Secretes bile into the gallbladder - Bile is stored until needed - Gall bladder - Secretes bile into the small intestine - Bile emulsifies fat so that enzymes can have access to break it down - Intestinal glands - Secretes intestinal juice into the small intestine - Intestinal enzymes break down carbohydrates, fats and protein fragments; mucous protects the intestinal wall

Sodium (Na+)

- Salt has been primary source of dietary sodium - Sodium has a critical role as an extracellular cation - Due to its fundamental role for survival, the development of a favourable taste perception is not surprising - Highly soluble and readily absorbed by intestines and travels easily in the blood - Removed via glomerular filtration in kidneys and the correct amount is added back into the blood - As more sodium is ingested, the person becomes thirsty, causing drinking, allowing more water to be excreted (removing sodium) until levels return to normal - Health considerations - Excess salt/sodium can cause hypertension and oedema - A diet consisting of high sodium intake usually is low in potassium - Average intakes of salt/sodium differ between countries - Food sources - Fresh fruit and vegetables and eats are low in salt and sodium - Processed foods are high in sodium (and low in potassium) - Deficiency - Sodium deficiency is very rare (possible in extreme dysentery) - Toxicity - Acute sodium toxicity results in oedema and raised blood pressure (hypertension) Nutrient Reference Values - Men/Women/ Women (pregnant)/Women (lactating) - AI = 460-920mg/day - Men and women UL = 2300mg/day - Most people consume well above these levels

Satiation

- Satiation - During a meal, hunger diminishes and satiation develops - Causes us to stop eating - Receptors in the stomach stretch, and hormones such as cholecystokinin increase - Satiety should remind us to not eat again until the body needs food - Satiation = stop eating - Satiety = don't start eating again

Sources of fats in our diet

- Saturated fats are found mainly in: dairy products, coconut and palm oil, hydrogenated products and eggs and meats (mainly the visible fat on meat) - Palm oil is common in processed foods and baked products - Cholesterol is found in eggs, meats, milk products but not plant material - Much of our dietary fat is invisible fat (e.g. French Fries and pastry could be up to 35% fat by weight) - Meat can be low in fat (~2%) if consumed as fat trimmed and from lean meat cuts. High fat meats include; hamburgers, sausages, salami and many processed meats, many of which can be 25-30% fat (by weight) - Studies that show the myth about red meat raising blood cholesterol - Most dietary fat in the Australian diet comes from: - Spreads and oils > take away foods > processed foods > diary foods > meat products > meat cuts

Fatty acids: Degree of saturation

- Saturation means the maximum number of hydrogen atoms (4) bonded to each carbon - If a double bond is inserted between 2 carbons then 2 hydrogens have to be lost and the fatty acid is no longer saturated with hydrogens, but is now a monounsaturated fatty acid (MUFA) - If more than one double bond is present the fatty acid is a polyunsaturated fatty acid (PUFA)

Phosphorous (P)

- Second most abundant mineral in the body, approx. 85% is in hydroxyapatite crystals (Ca5(PO4)3(OH)) which makes up approx 70% of the weight of bones and teeth - Small but critical amounts are found in all cells as part of the energy metabolism process mainly as ATP, ADP and AMP, in the phospholipids of cell membranes and also in DNA and RNA - Functions: - In all body cells as part of a buffer system involving phosphate (PO4(3-)) - Part of DNA and RNA as phosphate groups hence involved in growth - Involved in energy transfer on ATP, ADP and AMP - Also many enzymes and B vitamins require a phosphate group to become active - Lipid structure e.g. phospholipids which are needed in cell membrane structure and to transport other lipids in the blood (lipoproteins) - Some proteins also contain phosphorous (e.g. casein)

Proteins involved in appetite control, energy regulation and obesity development - Peptide YY (PYY)

- Secreted by GI cells - Signals satiety and decreases food intake

Proteins involved in appetite control, energy regulation and obesity development - Adiponectin

- Secreted by adipose tissue - Levels correlate inversely with body fat - Higher levels in lean vs obese people - Increases insulin sensitivity

Proteins involved in appetite control, energy regulation and obesity development - Ghrelin

- Secreted mostly by stomach cells - Triggers desire to eat

Sequencing errors

- Sequencing errors can cause altered proteins to be made - An example is sickle-cell anaemia, where valine replaces glutamic acid in the amino acid sequence of two of the polypeptide chains - As a result of this one alteration, the haemoglobin shape is altered (disc-shape to crescent or sickle-shape) and this interferes with the red blood cells ability to carry oxygen

What is alcohol's effects on the liver?

- Short-term: - NAD decreases causing the TCA cycle to slow - If NAD is insufficient for TCA cycle activity, the macronutrient molecules being broken down to acetyl-CoA have to be converted to fat - Long-term: - Fatty liver disease (reversible) -> fibrosis (reversible) -> cirrhosis (irreversible)

Calcium toxicity and deficiency

- Signs include: constipation, kidney stones and interference with absorption of other minerals - High blood calcium (not caused by diet) results in a condition known as calcium rigor in which muscles contract and cannot relax - Low blood calcium (may be diet-related in rare cases) results in a condition known as tetany, an involuntary contraction of muscles - Tetany or rigor generally result from lack of vitamin D or abnormal hormone secretion not calcium intake per se

Phospholipids

- Similar in structure to triglycerides but have only two fatty acids attached to a glycerol backbone. The third position is occupied by a combined phosphate/base group. - The four base groups that make up phospholipid molecules are: - Serine - Choline - Ethanolamine - Inositol - Hence there are four types of phospholipids: PS, PC, PE, PI

Other measures of body fat

- Skinfold measures - Hydrodensitometry (Hydrostatic weighing) - Bioelectrical impedance - Air displacement plethysmography (e.g. Bod pod) - Dual energy X-ray absorptiometry (DEXA)

Iron Absorption inhibitors (non-haem iron)

- Some dietary factors bind with non-haem iron, making it unavailable for absorption - E.g. phytates, oxalic acid, fibres, food EDTA, calcium, phosphorus (milk), tannic acid (wine), tea, coffee, nuts

Lipid usage and storage

- Some energy used by cells comes from TGs, these TGs are delivered to cells by: - Chylomicrons directly from food from the intestines - VLDL from liver storage - TGs are too large to pass from the blood through cell membranes so they are hydrolysed by lipoprotein lipase (LPL) into glycerol and free fatty acids, which are small enough and can be taken up by cells easily - Once absorbed into functional cells of the body the fatty acids and glycerol are metabolised for energy - Excess TGs are directed to adipocytes (fat cells) where LPL directs the breakdown products into the cells and cellular enzymes then reverse the process and recombine fatty acids and glycerol into TG molecules for energy storage - TGs are broken down (by LPL) and enter cells as fatty acids and glycerol, then reassembled as TGs

Iron from other sources

- Some intake can come from iron cookware and water supply - Iron supplements but are not as well absorbed as food, best form is ferrous sulphate or iron chelate - Vitamin C with iron supplements is of no value (already ferrous form) - Vitamin C helps with absorption by converting insoluble ferric iron to absorbable ferrous iron

Iron absorption and recycling in the body

- Some iron is lost when intestinal mucosal cells are shed and removed in the faeces - Some iron is lost in sweat, skin and urine - Some iron is lost in the blood - Breakdown of rbc in liver - Haemosiderin is an iron storage protein, when body iron levels become very high. Protects DNA cell lipids and protein from oxidation effect of free iron - Daily losses of iron are: ~1mg for males and ~1.3mg for females - Main iron losses are from GI tract lining cells when shed and excreted in faeces, also from bleeding and tiny amounts in urine and sweat - Iron is stored in many tissues bound to protein ferritin

Eating disorders

- Some people become obsessed about low body weight - They begin to view healthy weight as being 'too fat' - Around 9% of adolescent girls in Australia suffer from an eating disorder - Many reasons including: - Societal pressure to be thin - Comments about body weight from family and friends - Depression, anxiety

Tricarboxylic acid (TCA) cycle

- Sometimes referred to as citric acid cycle or Krebs cycle - TCA cycle involves a number of steps beginning with acetyl-CoA - Takes place in the mitochondria in the fluid-filled space between the internal membrane surfaces - A circular pathway yielding CO2 and hydrogen atoms carrying energy rich electrons from the energy rich chemical bonds that are broken apart (originating from Carbohydrates, Proteins and lipids) - The energy rich electrons are located on Hydrogen atoms removed from the various compounds in the TCA cycle. These Hydrogens (+electrons) are then picked up by carrier molecules (NAD and FAD and FMN) and transported from the TCA cycle (fluid region) to the ETC (inner membrane surface of the mitochondria - As with all cyclic reactions, it will run down, so must be complemented with new raw material constantly. The main one being acetyl-CoA - Some oxaloacetate is also added to keep the cycle functioning - Acetyl-CoA is the primary substance for the TCA cycle, however to stop the cycle running down, some pyruvate is added directly from the cytoplasm to form oxaloacetate, the last compound in the cycle. This then joins with the acetyl-CoA to perpetuate the reactions

Protein absorption

- Specific carriers in the membranes actively transport amino acids (and some di- and tri-peptides) into the intestinal cells - Intestinal cells may use the amino acids for energy or to synthesise new proteins - Amino acids not needed by intestinal cells are transported to the surrounding capillaries where they head to the liver

Digestion and absorption of carbohydrates

- Starch digestion begins in the mouth (salivary amylase breaks down starch) - No starch digestion in the stomach - Next stage of breakdown occurs in the duodenum, pancreatic amylase continues to breakdown starch molecules into disaccharides - Final breakdown occurs on the walls of the small intestine where brush border enzymes (maltase, sucrase and lactase) break down the disaccharides into monosaccharides - Note: almost half the carbohydrates we eat requires little or no digestion, as its already in disaccharide or monosaccharide form

Digestion of Starch

- Starch is composed of amylose (straight chain) and amylopectin (branched chain) - Carbohydrates are digested at different rates - Unbranched chains (amylose) are digested more slowly than branched chains (amylopectin) - In the branched form, enzymes have more places to attach and can release glucose into the bloodstream more quickly - Amylose to amylopectin ratio has been shown to predict the glycaemic index of foods - E.g. short and medium grain rice - high GI (amylopectin is predominant) vs long grain rich (high amylose) - low GI

Feasting and fasting response evolution

- Steps in energy metabolism are a result of millions of years of evolutionary development - Humans have evolved their own set of variations of energy metabolism to take into account times of food shortage or abundance that occurred regularly in our past. During these times we were subject to evolutionary pressures of survival of the fittest

Sterols

- Sterols contain multiple ring structures rather than fatty acid chains - They are found in plant and animal foods - The most well-known sterol is cholesterol - Cholesterol is found in animal foods only - meat, eggs, fish etc. - Plant-based sterols include; stigmasterol and campesterol - Plant sterols are present naturally in small quantities in many fruits, vegetables, nuts, seeds, cereals, legumes and vegetable oils - Plant-based sterols can interfere with cholesterol absorption in the small intestine, thus lowering blood cholesterol levels - Commercial products fortified with plant sterols include: Logicol and Flora Proactiv margarines

Other aspects of Vitamin C function

- Stress - Vitamin C is required in higher amounts in stress situations, mainly wound healing and infection - This is due to increased immune system activity which uses oxygen, producing dangerous oxidants (vitamin C inhibits their formation) - Hormones - Norepinephrine (noradrenaline a hormone and neurotransmitter responsible for mobilising the brain and body for action) and thyroxin (T4 - involved in regulation of metabolism) require vitamin C in metabolism of amino acids prior to their formation - The hormone producing adrenal glands are extremely rich in vitamin C. During stress the vitamin is released into the blood - Common cold - Despite public opinion and much social media claims, there is no evidence to suggest that Vitamin C cures colds and there is an increased requirement, except as a mild anti-histimine

Types of fat

- Subcutaneous fat - Found under the skin - Protective wrap over the body's surfaces - Visceral fat - Located inside the peritoneal cavity, between the organs - Contributes to belly fat - Strong correlation between centra adiposity and CVD, insulin resistance, type 2 diabetes, inflammatory disease, high blood pressure and other obesity-related diseases

Lifestyle strategies for addressing overweight/obesity

- Successful weight loss embraces small changes and reasonable goals - A lifelong eating plan for good health is best for achieving permanent weight loss; this includes: - Realistic energy intake - Regular physical activity - Permanent lifestyle changes - Weight loss of 0.25-1 kg per week or 10% of body weight in six months, is safe - Create an energy deficit of 2000-4000 kj/day - it should lead to 0.4-0.8kg/week - This rate of weight loss supports loss of fat and retention of lean tissue

Sugar-sweetened beverages

- Sugar-sweetened beverages refers to non-alcoholic water based beverages with added sugar (i.e. soft drinks, energy drinks, fruit drink, sports drink and cordial) - The term does not include 100% fruit juice, milk-based products or non-sugar sweetened drinks (i.e. artificial, non-nutritive sweetened drinks) - Energy intake of people who drink sugar-sweetened beverages is greater than those who choose to drink differently - They are easy to swallow, making it easy to overconsume energy - They are also cheap and widely available - These drinks cause blood glucose and insulin levels to rise

Sugar vs sugars

- Sugars - used to describe all monosaccharides and disaccharides in food - Sugar - only refers to 'table sugar' or sucrose - Added sugars - sugars that food manufacturers add to products to increase flavour or extend shelf life - Intrinsic sugars - sugars incorporated in the structure of intact fruit and vegetables - Total sugars - include naturally occurring sugars and sugars added as ingredients of the good - Intense sweeteners - provide an intense sweet flavour, i.e. artificial sweeteners or sugar substitutes

Sulphur (S) (also as sulfate (SO4(2-)))

- Sulphur is important as part of thiamine, biotin, insulin and the amino acids methionine and cysteine - Cysteine controls the 3D shape of proteins by forming a link with another cysteine in a different part of the chain by a 'disulphide bridge' - No RDI - No deficiency states are known - Most sulphur in the body is in proteins

Vitamin D and skin colour

- Sunlight impairs folate production which is important for reproduction - People with light skin have less reproductive success in areas in areas with lots of sunlight

Food versus supplements of Vitamin E

- Supplemental vitamin E is not recommended due to lack of evidence supporting any added health benefits - A few studies have raised the possibility that taking antioxidants supplements, either single agents or combinations, could interfere with health - One meta-analysis of 19 clinical trials of vitamin E supplementation found a higher rate of death when supplementation was more than 400 IU/day - A more recent meta-analyses of 56 randomised trials found that supplemental vitamin E, singly or in combination with other antioxidants did not significantly alter the risk of all-cause mortality - Vitamin E obtained from food does not pose a risk for toxicity

Are sugars addictive?

- Sweet foods trigger the mesolimbic dopamine system - the reward system in the brain - Dopamine has an important role in the brain, directing our attention towards things in the environment like sugary foods - As sugary foods are readily available, this means our attention can be drawn to chocolate bars and sugary drinks when we're not necessarily hungry, evoking cravings - People also experience symptoms of withdrawal when they quit sugary foods

Vitamin B9 (Folate) Deficiency

- Symptoms: - Elevated homocysteine levels - Macrocytic/Pernicious anaemia resulting from folate or B12 deficiency: - Without folate, DNA strands break and cell division diminishes - RNA synthesis continues, resulting in a large cell with a large nucleus - Red blood cells are relatively large (macrocytic), irregularly shaped and often have a nucleus - don't function efficiently Deficiency in pregnant women can lead to birth defects Toxicity symptoms - None known, - However excess dietary folate (supplementation) can mask a vitamin B12 deficiency - Nutrient reference values for Folate are: - RDI: 400 ug/day for men/women (>19 years) - RDI: 600 ug/day for women (pregnant) - RDI: 500 ug/day for women (lactating) - UL: 1000 ug/day

Vitamin K summary

- Synthesis of blood-clotting proteins and bone proteins - Deficiency symptoms = Haemorrhage - Toxicity symptoms = none known - Significant sources = synthesised in the body by GI bacteria; green leafy vegetables

The nutrient reference values (NRV)

- Systems of nutritional references designed to give guidance on adequate nutrient intakes as well as toxic levels - Outline the levels of intake of essential nutrients based on scientific knowledge, to be adequate to meet the known nutritional needs of practically all healthy people for the prevention of deficiency - Nutrition experts have produced a set of standards that define the amounts of energy, nutrients, other dietary components and physical activity that best supports health, 'Nutrient Reference Values' - RDIs - EARs - AI - UL

Cellular respiration of Carbohydrates - Step 3: Aerobic metabolism (Krebs/TCA cycle)

- Takes place in the mitochondria, where pyruvate has been converted to acetyl-CoA and is about to enter the TCA cycle - Acetyl-CoA enters the TCA cycle where it is metabolised in an aerobic environment (O2) to yield a series of compounds, liberating CO2 at certain stages along with hydrogen atoms (taken up by NAD to produce NADH+). These Hydrogens possess high energy electrons from the chemical bonds of nutrient molecules - Each glucose molecule that entered glycolysis will yield another 2 ATP in the TCA cycle and up to 34 more in the ETC - Although there is a theoretical yield of 38 ATP molecules per glucose during cellular respiration, such conditions are generally not realised because of losses such as the cost of moving pyruvate (from glycolysis), phosphate and ADP (substrates for ATP synthesis) into the mitochondria. All are actively transported

Health effects of sugars

- The Australian dietary guidelines recommend limiting food or drinks containing added sugars - Excessive intake of dietary sugars can contribute to the development of: - Nutrient deficiencies - through displacement of needed nutrients and fibre - Dental cavities - sugars ferment in the mouth and can produce an acid that erodes tooth enamel causing tooth decay - Not all sugars need to be avoided; only concentrated sources (i.e. lollies, soft drinks)

Added sugars

- The Australian dietary guidelines recommend limiting food or drinks containing added sugars, such as: - Confectionary - Soft drinks - Cordials - Energy drinks - Sports drinks - Food labelling currently only lists total sugars which lumps together the naturally occurring sugars with the added sugars which makes it difficult for consumers to weigh up how good/bad a product is - How to be added sugars savvy: - Look out for added sugars hidden under the following names on the product's ingredients list: - Brown sugar - Corn sweeteners - Corn syrup - Dextrose - Granulate sugar - High-fructose corn syrup - Honey - Icing sugar - Levulose - Molasses - Raw sugar - White sugar - Compare similar products to estimate how much added sugars there are - Chocolate flavoured full-cream milk (total sugars = 10%) - Full-cream plain milk (total sugars = 6%) - Assume content of added sugars is 4% in chocolate milk

Electron transport chain

- The ETC consists of a series of proteins which carry electrons. The proteins are mounted in sequence on the inner membrane surfaces in the mitochondria - As each carrier protein receives an electron it removes some of the energy from the electron and passes the electron along to the next protein in the chain - Much of the released energy is stored as ATP and some is liberated as heat - Electrons pass along the ETC attached to hydrogen atoms, giving up a little of their energy at each protein in the chain - At the end of the chain the electrons have low energy levels. In this state the Hydrogens carrying them react readily with oxygen to form water - Final products of the ETC are energy in the form of ATP as well as H2O molecules

The gastrointestinal (GI) tract

- The GI tract is the flexible muscular tube from mouth to anus - Digestion begins in the mouth, where salivary glands secrete salvia (starch digesting enzymes) and chewing (mastication) breaks down food - The epiglottis is a flap in the throat that prevents food entering the windpipe - After swallowing, the food (bolus) heads into the oesophagus, where the oesophageal sphincter controls the passage from the oesophagus to the stomach - The stomach adds juices and grinds the bolus into chyme (semi liquid) - The pyloric sphincter regulates the flow of chyme into the small intestine - The three segments of the small intestine are the duodenum, the jejunum and the ileum - The small intestine receives bile and digestive juices from the gallbladder and the pancreas - The large intestine (colon) begins at the ileocecal valve and undigested residues continue through to the rectum (forms stool) and excreted (anus) - Meal digestion time = three to four hours

Meeting the RDIs

- The RDI include a generous margin of safety - The RDI is intended to be met through dietary intake of a variety of foods - Meeting the RDI for each nutrient every day is difficult and not necessary. This is dependent on the body's use and storage of that nutrient - Intake of most water soluble vitamins (i.e. thiamin, vitamin C) can be averaged over several days to meet needs where as intake of fat soluble vitamins (i.e. vitamin A and even B12) can be averaged over weeks and still meet needs

Lipid absorption

- The absorption of lipid breakdown products is quite different to absorption of other nutrients - Once emulsified lipids are easily broken down into smaller molecular units by pancreatic and intestinal lipase enzymes - The smaller chemical units are glycerol and short, medium and long-chain fatty acids - Glycerol and smaller fatty acids can enter the intestinal lining cells easily - Some TG is not fully broken down and form monoglycerides - These monoglycerides and long-chain fatty acids are large on the molecular scale. They are more water-insoluble and form spherical complexes called micelles that then enter the intestinal mucosal cells - Monoglycerides and longer chain fatty acids then combine with cholesterol and proteins to form chylomicrons in the mucosal cells - Chylomicrons enter the lymph in the villi where they reach the circulatory system at the thoracic duct and subclavian vein in the upper chest region - Chylomicrons are large lipoprotein particles that take larger lipid products via lymph vessels in the villi bypassing the liver - The smaller fatty acids enter the blood vessels in the villi along with other nutrients and are taken via the Portal Vein to the liver

Factors affecting the glycaemic response

- The amount of carbohydrate in a food - E.g. watermelon and pumpkin are low in carbohydrate - Nature of the monosaccharide - E.g. glucose, fructose, galactose - Nature of the starch - E.g. amylose, amylopectin, resistant starch - Cooking/food processing - E.g. degree of starch gelatinisation, particle size, food form - Other food components - E.g. fat and protein, dietary fibre

Lipids in food

- The chemical form of lipids in the food you eat - Triglycerides ~95% (solid and liquid) (fats and oils) - Phospholipids ~4.5% (solid) (plant and animal cell membranes) - Sterols ~0.5% (solid) (plant and animal tissue) - Both triglycerides and phospholipids contain fatty acids - Sterols are chemical ring structures without fatty acids

Lipids

- The term lipids refers to fats and oils (only difference is melting point) - There are many types of lipids - complex chemical classification system based on their molecular structure - The main dietary lipids are triglycerides (~95%), phospholipids (~4%) and sterols (~1%) - Whether they are a fat or an oil, triglycerides are still digested and absorbed the same way, only the palatability and texture is different

Vitamin B1 (Thiamine) Deficiency

- The common term for thiamine deficiency is Beriberi - Both wet and dry beriberi can be treated with thiamine supplements - Common in populations consuming high white rice diets with little other food types, as the thiamine containing germ portion of the rice grain is removed in the milling process - Wet Beriberi - Thiamine deficiency leads to nerve tissue damage, paralysis, oedema and muscle wasting - Wet beriberi affects the heart and circulatory system. Its sometimes fatal, as it causes a combination of heart failure and weakening of the capillary walls. Wet beriberi is characterised by: - Increased heart rate - Vasodilation - Dyspnea (shortness of breath) on exertion - Peripheral oedema (swelling of lower legs) - Dry Beriberi - Alcohol-induced form of thiamine deficiency called Wernicke-Korsakoff syndrome common in alcoholics - Alcohol displaces food from the diet and lowers thiamine intake and increased urinary excretion of thiamine - Dry beriberi causes wasting and partial paralysis resulting from damaged peripheral nerves (neuropathy). Its characterised by: - Difficulty walking - Tingling or loss of sensation (numbness) in hands and feet - Loss of tendon reflexes - Loss of muscle function or paralysis of the lower legs - Mental confusion/speech difficulties - Pain - Involuntary eye movements - Vomiting - Brain damage - Beriberi: Symptoms of this disease of the nervous system include: - Weight loss, - Emotional disturbances, - Wernicke encephalopathy (impaired sensory perception), - Weakness and pain in the limbs, - Irregular heartbeat and - Oedema (swelling of bodily tissues). - Heart failure and death may occur in advanced cases

The elderly and vitamin D

- The elderly are particularly vulnerable to vitamin D deficiencies because: - They lose the capacity to make and activate vitamin D - They drink little milk - They spend little time outdoors and when they do they wear productive clothing - This can contribute to bone loss and its resulting consequences (fractures)

Chloride (Cl-)

- The elemental form of chlorine is a poisonous gas (Cl2) which forms the chloride anion (Cl-) in solution - Chloride is the major anion of extracellular fluid (outside the cell) - Chloride ions can move freely across cell membranes - Chloride is critical in maintenance of fluid and electrolyte balance and is an essential component of stomach hydrochloric acid - Recommended dietary intake - No recommended intake In Australia as diets rarely lack chloride - Deficiency - Rare but will lead to death - Can occur temporarily in vomiting and diarrhoea during heavy sweating

Metabolic processes: energy transfer

- The energy contained in the macronutrients that we consume is in the chemical bonds joining the atoms within these molecules - Carbohydrates contain 17kj of extractable energy per gram, proteins likewise contain 17 kj/g and lipids 37 kj/g - Energy released from catabolic reactions is captured by 'go between' molecules that transfer energy to other compounds for anabolic reactions later in time or at a different location - Some energy is lost in the process and escapes as heat - These 'go between' compounds are referred to as 'high energy compounds' or 'common energy currency'. The most important is adenosine triphosphate (ATP) - ATP contains adenosine, ribose and 3 phosphate groups, which have high energy bonds capable of storing energy and releasing it easily at a later stage when needed - The energy in ATP is stored in 3 high energy phosphate bonds that link the phosphate groups to the adenosine fraction, only 2 are usually removed

Fasting - formation of ketone bodies

- The first step in the formation of ketone bodies is the condensation of two molecules of acetyl-CoA and the removal of CoA to form a compound that is converted to the first ketone body - This ketone body may lose a molecule of CO2 to become another ketone - Or, the acetoacetate may add two hydrogens, becoming another ketone body (beta-hydroxybutyrate)

Vitamin B9 (Folate) - Activation of THF

- The folate is absorbed with only one glutamic acid attached - A methyl group is then attached to the remaining glutamic acid end - Once formed the methyl-THF is inactive and is stored in this form until needed - Activation occurs by removal of the methyl group by vitamin B12 - The THF now becomes active and the vitamin B12 now with a methyl group is activated also. Thus the two vitamins work in unison

Glycaemic index

- The glycaemic index is defined as: the incremental area under the blood glucose response curve when consuming a 50g carbohydrate portion of a test food exressed as a percent of the response to the same amount of carbohydrate from a standard food - GI = ((AUC test food)/(AUC glucose)) x 100

Gut microbiome

- The gut microbiome - the collection of microorganisms that inhabit the gut - adapts with age, diet, stress, supplements and medication; but each individual has a microbiota "fingerprint" that is relatively stable - Healthy gut microbiota functions to: - Support the immune system - Protect against opportunistic pathogens - Digest food to release nutrients and energy - Ferment non-digestible carbohydrates - Synthesise vitamins (vitamins K, B12, biotin and carnitine) - Stimulates renewal of intestinal lining - Provide regulatory signals via the gut-brain axis - A breakdown in the balance of protective and harmful intestinal bacteria, gut dysbiosis, produces an inflammatory state and has been associated with changes in glucose metabolism, insulin sensitivity and dyslipidaemia

Cellular respiration of Carbohydrates - Step 4: Electron transport chain (ETC) + Coenzyme Carriers

- The high energy electrons are carried from the TCA cycle (mitochondrial fluid) to the ETC located on the inner mitochondrial membranes, by coenzyme carrier molecules such as NAD (NADH) and FAD (FADH2) molecules - NAD is based on the B group vitamin niacin, often termed nicotinamide. It picks up a H atom possessing a high energy electron becoming NADH. It moves this H atom and electron to the ETC - A second carrier coenzyme is FAD (FADH2), based on the B group vitamin riboflavin. FAD can pick up two Hydrogens with high energy electrons and carry them from the TCA to the ETC - If energy is not required to be produced, acetyl-CoA does not enter the TCA cycle. Instead multiple acetyl-CoA molecules are joined to form fatty acid molecules, which are linked to a glycerol molecule to form a triglyceride molecule, this will be transported to and stored in an adipocyte cell - High energy electrons from bond breakage are carried from the fluid (TCA cycle) to walls (ETC) by carrier molecules NADH and FADH2 (coenzymes of B group vitamins)

Vitamin A in vision

- Vitamin A (retinal) plays two roles in the eye: - Helps maintain a crystal clear cornea - Participates in the conversion of light energy into nerve impulses at the retina - Rhodopsin is a pigment molecule within the cells of the retina. Visual activity leads to repeated losses of retinal (as retinoic acid), necessitating constant replenishment from foods or retinol stores

Hormonal control of the GI tract

- The hormonal (or endocrine) system and the nervous system coordinate all digestive and absorptive processes - The GI tract stimulates or inhibits secretions of hormones via nerve-pathway 'feedback mechanisms' - Pancreatic secretions change based on the contact of the diet. A rapid change to the typical diet can often result in 'upset stomach' due to lag in pancreatic secretions - Gastrin - Responds to food in the stomach - Secreted from the stomach wall to stimulate the stomach glands - Hydrochloric acid secreted into the stomach to maintain an acidic pH - Secretin - Responds to acidic chyme in the small intestine - Secreted from the duodenal wall to stimulate the pancreas - Bicarbonate-rich juices secreted into the small intestine to maintain a slightly alkaline pH - Cholecystokinin - Responses to fat or protein in the small intestine - Secreted from the intestinal wall to stimulate the gall bladder and pancreas - Bile secreted into the duodenum to emulsify fats. Bicarbonate- and enzyme-rich juices are secreted into the small intestine to maintain a slightly alkaline pH, digest fats and proteins and slow GI tract motility

Mastication (chewing)

- The human jaw is one of the most powerful muscles in the body (max hand strength = 40psi; human jaw strength = >100psi) - Tooth enamel is the hardest substance produced by the body - The tongue is a conglomeration of eight different muscles, which makes it the body's most flexible muscle - Several glands (including sublingual, submandibular and parotid) secrete saliva to help dissolve food and provide particles in solution to react with taste buds

Body fat and its distribution

- The ideal amount of fat depends partly on the person - Fat is required for a number of functions, including: - Fat provides energy - Fat insulates against temperature extremes - Fat protects against physical shock - Fat forms cell membranes - Fat makes compounds such as hormones, vitamin D and bile - Fat distribution and location is the key to health outcomes - Fat stored around the organs of the abdomen = central obesity or intra-abdominal fat - Fat deposited in the abdominal cavity strongly predisposed to metabolic syndrome, type 2 diabetes and heart disease

How the body regulates water retention

- The kidneys respond to reduced blood flow by releasing the enzyme renin - Renin initiates the activation of the protein angiotensinogen to angiotensin - Angiotensin causes the adrenal glands to secrete aldosterone which causes the kidneys to retain sodium (and thus water) - Angiotensin also causes the blood vessels to constrict and thus raises BP - The hypothalamus responds to high salt concentrations in the blood by stimulating the pituitary gland - The pituitary gland releases antidiuretic hormone (ADH) which causes kidneys to retain water

Vitamin E as an antioxidant

- The main role of vitamin E is to act as an antioxidant, scavenging loose electrons - so-called 'free radicals' that can damage cells, particularly the cell membranes (lipid peroxidation) - The body is exposed to free radicals from the conversion of food to energy, as well as environmental exposures, such as cigarette smoke, air pollution and ultraviolent radiation from the sun - In mopping up free radicals, vitamin E helps to protect vulnerable components of a cells membrane - Epidemiological studies show that high intakes of vitamin E are associated with lower rates of death from heart disease - Vitamin E protects LDL against oxidation and reduces inflammation - two factors involved in the development of artery clogging atherosclerosis

When consuming foods you consume both the atoms that make up the foods and also the energy of the bonds between the atoms

- The metabolised atoms become either; waste, new molecules or fat storage - The metabolised energy becomes either; heat, BMR, exercise and metabolism or excess goes into fat storage

Macronutrients and satiety

- The nutrient composition of a meal can affect satiety - Protein-rich foods are considered the most satiating (more than fat- and carbohydrate-rich foods) - Energy-dense, high-sugar/high-fat foods encourage passive overconsumption, but not satiation

Carbohydrate metabolism

- The primary role of carbohydrates is to provide glucose for energy - Glycogen is the storage form of carbohydrates in the body - The body has limited glycogen stores (muscle, liver and a small amount in the brain) which lasts only up to a day - If glycogen stores are depleted the body makes glucose from protein - Gluconeogenesis is the conversion of protein to glucose - Protein-sparing action is having adequate carbohydrate in the diet to prevent the breakdown of protein for energy - Ketone bodies are metabolic products that are produced during excessive breakdown of fatty acids - During prolonged starvation, very low carbohydrate diets and uncontrolled diabetes, ketones accumulate in the blood causing ketosis - Very high levels of blood ketones can disturb the body's normal acid-base balance, leading to ketoacidosis, a life-threatening condition - To spare body protein and prevent ketosis, the body needs 50-100gms of carbohydrates a day

Cellular respiration of Carbohydrates - Step 2: Pyruvate to Acetyl-CoA

- The second step in carbohydrate metabolism involves the movement of pyruvate into the mitochondria and conversion of the pyruvate into acetyl-CoA (with the release of CO2) - Pyruvate -> Acetyl + Coenzyme A -> Acetyl-Coenzyme A - This step is not reversible. Glucose can be reformed from pyruvate while still in the cytoplasm but not from acetyl-CoA once in the mitochondria

Inositol and Carnitine - Potential vitamin candidates

- The situation with these two compounds is less clear and it seems the body can synthesis the amount required. No intake levels have been set - Inositol like choline is a component of phospholipids in cell membranes - Carnitine is needed as a part of the carnitine transferase enzyme, to move fatty acids from the cytoplasm to the mitochondria for metabolism into energy - The body can make carnitine and does so locally where needed in the cytoplasm - There is controversy over whether dietary/supplemental carnitine actually gets to the cell cytoplasm where needed

Mechanical stomach action

- The stomach adds juices to the bolus and grinds it up to a semi-liquid mass called chyme - Stomach has the thickest walls and strongest muscles of all the GI tract organs - These sets of muscles churn the food (longitudinal, circular and diagonal) for hours, grinding the mouthfuls of food into tiny particles - Stomach can stretch to hold more than 20 times its empty volume. Rugae (gastric folds) allow the stomach to stretch and accommodate a meal

Osmosis

- The water molecule is polar (partly positive and partly negative) due to the ability of the oxygen atom to attract the pairs of electrons making up the covalent bonds, more strongly than the hydrogen atom - The negative electrons spend a greater amount of time in the vicinity of the oxygen on their constant movement between the oxygen and hydrogen atoms - In this way the oxygen has a partial negative charge and the hydrogens have a partial positive charge - Due to this polarity, the water molecule is attracted to and attaches to ions which have complete positive and negative charges - Water tends to follow these ions (electrolytes) and in fact clusters around them - Water will move into the area with the greatest concentration of ions i.e. a diluting effect to reach equilibrium

Digestion of Fibre

- There are two main types of fibre: - Insoluble fibre - Speeds up the passage through the GI tract - Bulking fibre (roughage), which even gut bacteria won't eat (minimal fermentation), speeds up transit in the bowel - Not a source of calories - Soluble fibre - Slows digestion - Holds water, forms a gelatinous blob in the gut that slows digestion, easily fermented in the gut producing gases and short chain fatty acids - All plant foods - vegetables, fruit, legumes and grains - contain a mixture of fibres and each type plays an important role in the body - Fibre can't be digested by human enzymes - There is usually much more insoluble fibre in plant foods than soluble fibre - A more recent addition to the list is resistant starch which while not traditionally thought of as a fibre has been found to act a similar way - Resistant starch doesn't get digested and ends up as food for bacteria in the large intestine

LDL/HDL Health Implications

- There is excess cholesterol being transported in LDL particles by people consuming westernised diets. This is due to a high saturated fat intake in the diet - Saturated fats do not make cholesterol themselves but up-regulate the production of cholesterol in the liver and decrease its removal from the body - The high amounts of LDL-cholesterol are correlated with increased CHD rates - As cholesterol in HDL is being removed from cells and blood vessels to the liver. High HDL cholesterol is correlated with lower CHD death rates - HDL particles are made in the liver and rate of production responds to exercise - The higher a person's LDL:HDL cholesterol ratio the greater the probability of premature cardiac events - Clear message is to lower LDL cholesterol by decreasing intake of saturated fat and increase HDL cholesterol by increasing exercise - The greater the LDL:HDL cholesterol ratio the greater the chance of coronary events such as heart attacks - The result of chronically raised LDL:HDL cholesterol levels is arterial blockage by plaque - As the coronary arteries are relatively narrow, divided and crucial to heart function, any blockage in these can lead to a heart attack (MI)

Magnesium (Mg2+)

- There is only approx 25g magnesium in the body, over half of which is in the bones and the remainder is predominantly in soft tissues - Less than 1% is found in extracellular fluids - As with calcium and phosphorous, bone magnesium acts as a reservoir to ensure constant blood magnesium levels - Widespread in foods - Roles in the body include: - Bone mineralisation - Building of proteins - Enzyme action - Muscle contraction - Maintenance of teeth by preventing dental decay - Functioning of the immune system - Blood clotting - Nerve impulse transmission - Functions: - Involved in energy metabolism, particularly as a catalyst for the addition of a phosphate group to ADP to produce ATP and in the body's use of glucose - Assists over 300 enzymes acting as a cofactor in the production of proteins, fats and nucleic acids in cells - Involved in blood clotting and muscle contraction. - Holds calcium in tooth enamel preventing dental decay - Supports the normal functioning of immune system and is involved in nerve impulse transmission - Protects against heart disease and hypertension (low magnesium restricts walls of arteries and capillaries)

PUFA families

- There is variation in location of double bonds as well as their number - This effects the behaviour of the fatty acids in the body, particularly how it is metabolised, what function it serves in the cell membrane and the effects on overall health - Main PUFA subgroups are: - Omega-6 - Omega-3 - Other families or subgroups are: - Omega-7 - Omega-9

How do Vitamin B9 and Vitamin B12 work together?

- They activate each other - Vitamin B9 acts as a methyl donor whilst Vitamin B12 acts as a methyl transferer

Food sources of Vitamin B1 (Thiamine)

- Thiamine is found in many foods such as whole grains, meat and fish, but is particularly rich in ham, pork, sunflower seeds, watermelon, fortified cornflakes and soy milk - Fortified cornflakes, Tomato juice, Soy milk, lean pork chop, Squash - Thiamine is lost from grains in milling (removal of germ of grain) and is easily destroyed by prolonged heating in food processing and leached from foods when cooked in water - Toxicity symptoms - None known - Nutrient reference values for Thiamine: - RDI = 1.2 mg/day for men (>19 years) - RDI = 1.1. mg/day for women (>19 years) - RDI = 1.4 mg/day for women (pregnant, lactating)

Functions of water soluble vitamins

- Thiamine, riboflavin, niacin, vitamin B6, pantothenic acid (Vitamin B5) and biotin function as co-enzymes in the many metabolic reactions involving the release of energy - Vitamin B12 and folate are involved in the synthesis of DNA (and repair) - Vitamin C is an antioxidant and also involved in collagen synthesis - Vitamin B6 is a coenzyme involved in amino acid metabolism - Folate and vitamblin B12 are involved in cell division - Several water soluble vitamins carry out functions involved with blood cell formation and cell division (folic acid, B12, B5 and B6) as well as antioxidant function

Vitamin B2 (Riboflavin) Functions

- This vitamin is a tricyclic ring structure composed of C, H, O, N - One of its most important functions is as the coenzyme Flavin adenine dinucleotide (FAD) (and FMN) involved in numerous reactions including the movement of Hydrogen atoms and their energy electrons from the TCA cycle to the ETC A precursor of coenzymes FAD and FMN, which are needed for flavoprotein enzyme reactions

The 2013 Australian Dietary Guidelines - Guideline 1

- To achieve and maintain a healthy weight, be physically active and choose amounts of nutritious food and drinks to meet your energy needs - Children and adolescents should eat sufficient nutritious foods to grow and develop normally. They should be physically active every day and their growth should be checked regularly - Older people should eat nutritious foods and keep physically active to help maintain muscle strength and a healthy weight

Evaluating Published Research

- To be accepted into the body of nutrition knowledge, a finding must stand up to rigorous, repeated testing in experiments performed by several different researchers - A peer review process is used to evaluate the procedures and the conclusions drawn from a study - Published studies should be evaluated for reliability based on: - The journal (impact factor in its class) - Study funding source - Authors (relevant discipline training, society membership, track record etc.) - The study methodology and discussion of results (e.g. do the conclusions and the results match?) - Replication should be used to confirm or disprove findings

Diet planning principles - Nutrient Density

- To eat well, without consuming excess energy - Select nutrient-dense foods - E.g. whole grains, fruits, vegetables, reduced-fat milk and milk products, seafood, lean meats and poultry, eggs, beans and peas and nuts and seeds - I.e foods with most nutrients per kJ or per serve

Toxicity of vitamin K

- Toxicity is rare; no known adverse effects of high intakes - High intakes can reduce effectiveness of anticoagulant drugs to prevent clotting - No upper level of intake

Toxicity of Vitamin E

- Toxicity is rare; the least toxic of the fat-soluble vitamins - Extremely high doses may interfere with blood clotting, which increases the likelihood of excessive bleeding (haemorrhage) in some individuals (i.e. those on blood-thinning medications such as Warfarin)

Lipoproteins

- Transport vehicles for lipids around the body - There are four types: - Chylomicrons (made in the intestinal lining cells) - VLDL (made in the liver) - LDL (made in the liver) - HDL (made in the liver) - They have a polar protein group on the particles surface and the outward facing polar regions of the phospholipids allow the lipoprotein to be suspended in a watery environment - The more non-polar substances including triglycerides and cholesterol can stay in the interior of the particle away from contact with water - The protein molecules and phospholipid heads are hydrophilic and are on the surface - The lipids such as TGs and cholesterol are hydrophobic and are embedded inside the particles - Chylomicrons are the largest (by far) of the lipoproteins - Too big to fit in the portal vein?

Triglycerides

- Triglycerides have a high ratio of C and H to O thus have high energy - Energy dense because of the many C-H bonds - Have a glycerol backbone - Three fatty acids (with even carbon number) - Fatty acids may be saturated, monounsaturated or polyunsaturated - Usually three different fatty acids on each triglyceride molecule

Vitamin B9 (Folate) Functions

- Triple ring structured complex made up of C, H, O, N and is often referred to as folic acid or folacin, depending on its exact molecular structure - The various forms are easily inter-converted and have the same biological function - Chemical name for folate is pteroylglutamic acid (PGA) - Folate contained in our food consists of the ring structure with multiple glutamic acids (an amino acid) attached - The supplemental form of folate has only one glutamic acid unit attached - Folate forms the coenzymes: - Dihydrofolate (DHF) and - Tetrahydrofolate (THF) - Important in the metabolism of 1C compounds. That is in adding or removing methyl (CH3) groups during metabolic processes A precursor to make, repair and methylate DNA; a cofactor in various reactions; especially important in aiding rapid cell division and growth, such as infancy and pregnancy Folate and B12 often work as a pair and one doesn't work without the other

A healthy diet is essential for a healthy body and its important to consider nutritional properties of food when making choices

- Unfortunately for many people this is the least considered aspect of food choice - For others their concept of healthy foods is misdirected by poor media including social media

The effect of processing on food sodium and potassium levels

- Unprocessed foods have high potassium and low sodium - Processed foods have high sodium and low potassium

To ensure the validity of results these concepts are used (experimental criteria)

- Use of controls - Determination and use of adequate sample size - Placebos - Randomisation of subjects - Blinded and double blinded - Correct and adequate statistical analysis of results - Peer review of studies prior to publication - Publication in reputable journals in the discipline area (high impact factor) - Future replication of study findings prior to general acceptance

Deamination and elimination of amino acids

- Using amino acids to make glycogen and fat - There are no specialised storage sites for protein. When protein intake exceeds demand, protein is converted to glucose or ketone bodies to be stored as glycogen or fat. ~10-15% of dietary protein is used as energy - Deaminating amino acids - Amino acids are stripped of their amino group, resulting in ammonia and a keto acid. Keto acids can be used for energy metabolism (TCA cycle) or fat production. - Converting ammonia to urea - Excess ammonia is toxic (upsets acid-base balance). The liver combines ammonia with CO2 to make urea, a much less toxic compound - Excreting urea - Urea is excreted in solution (water)

Types of vegetarian/almost vegetarian diets

- Vegan - Does not consume: - Meat - Meat by-products (gelatin, animal broths) - Animal by-products (eggs, dairy, honey) - Lacto vegetarian - Does not consume: - Meat - Meat by-products (gelatin, animal broths) - Certain animal by-products (eggs) - does consume dairy - Ovo vegetarian - Does not consume: - Meat - Dairy by-products (milk, cheese) - does consume eggs - Lacto-ovo vegetarian - Does not consume: - Meat - Pollotarian - Does not consume: - Red meat (beef, lamb, pork, venison) - Fish and seafood - Pescatarian - Does not consume: - Red meat (beef, lamb, pork, venison) - Poultry and fowl - Flexitarian - Plant-based diet with occasional animal food consumption

2019 Meta-analysis of vegetarians and vegans

- Vegetarians and vegans had lower bone mineral density at the femoral neck and lumbar spine (vs omnivores) - Vegans had higher fracture rates (40% higher risk) compared with omnivores

Vitamin A summary

- Vision; maintenance of cornea, epithelial cells, mucous membranes, skin; bone and tooth growth; reproduction; immunity - Deficiency symptoms = infectious diseases, night blindness, blindness (xeropthalmia), keratinisation - Toxicity symptoms = reduced bone mineral density, liver abnormalities, birth defects - Significant sources = retinol: milk and milk products, beta-carotene: dark green leafy and deep yellow/orange vegetables

A brief history of Vitamin A

- Vitamin A is essential for good vision - It is recorded in history that Hippocrates cured night blindness (~500 BC) - He prescribed Ox liver (in honey) which is now known to contain high amounts of vitamin A - By 1917, McCollum and Davis from the University of Wisconsin-Madison, studied the role of fats in the diet and discovered a few "accessory factors" - These "accessory factors" were termed fat-soluble in 1918 and later 'vitamin A' in 1920

Other roles of Vitamin A in the body

- Vitamin A plays a role in cell differentiation and helps the specific functions of: - Epithelial cells - helps to protect against skin damage from sunlight - Goblet cells (glands that secrete mucous) - vitamin A helps maintain the structural integrity of the mucous membranes (e.g. GI tract) - Vitamin A supports reproduction and growth - Supports sperm development in men - Support normal foetal development in women - Growth in children (participates in bone remodelling) - Beta-carotene acts as an antioxidant

Signs of vitamin A toxicity - Toxicity disease is called hypervitaminosis A

- Vitamin A toxicity can occur with concentrated amounts of pre-formed vitamin A from animal foods, fortified foods or supplements - Side effects include: - Birth defects - Excessive vitamin A is teratogenic (causes malformations). High intakes before the 7th week of pregnancy is most damaging - Bone defects - Weakens bones and contributes to fractures and osteoporosis - Discolouration of skin - Overconsumption of beta-carotene from foods may turn skin yellow

Vitamin B12 (Various cobalamins) - Digestion, Absorption and Transport

- Vitamin B12 is attached to proteins in food and must be removed by HCl and pepsin (stomach enzyme) during digestion - An intrinsic factor (glycoprotein carrier) is attached to vitamin B12 in the stomach, which is essential to allow absorption into the bloodstream from the small intestine

Considerations when selecting a vegetarian or vegan diet

- Vitamin B12 is only available from animal food sources - vegans will require supplements - To obtain sufficient amounts of omega-3 fatty acids, vegetarians to consume flaxseed, walnuts, soybeans and products derived from these (or algae n-3 supplements) - Vitamin D may be low unless fortified foods are consumed or sunlight exposure of the skin occurs - Nuts and seeds and legumes/beans are important if meat is omitted as they provide an alternative source of nutrients, including protein - Protein is particularly important for growing children/adolescents and older people to decrease the risk of sarcopenia and frailty - Other alternative protein sources include textured vegetable protein, tempeh and tofu - For iron, zinc, calcium and vitamin B12, animal foods are highly bioavailable sources - take care to ensure adequacy of a plant-based diet - Iron is important for young and middle-aged women, calcium needs are high for adolescents and older adults - E.g. phytate and oxalate in some plants can reduce calcium bioavailability - Fortified dairy 'alternatives' do not contain the same range of nutrients and dairy foods - They must contain >100mg of added calcium/100ml to be considered part of the food group

Water soluble vitamins

- Vitamin C - B - Group - Thiamine - Riboflavin - Niacin - Folic acid - Pantothenic acid - Biotin - Pyridoxal - Cobalamin - There is no singular vitamin B - only vitamin B group

Vitamin C - Collagen formation

- Vitamin C assists in the formation of the structural protein collagen, which is a fundamental component of connective tissue (cartilage, bones, blood vessels etc. - Collagen contains many proline and lysine groups, which must be hydroxylated prior to their addition to the peptide chain - This reaction requires the enzyme hydroxylase which requires iron as a cofactor - Cofactors are often minerals - Iron in turn requires vitamin C to maintain it in the correct oxidative state

Vitamin C - Role as an antioxidant

- Vitamin C is oxidised in preference to other substances and therefore protects them - As an antioxidant it is often added to processed foods as a preservative - In the body it is involved in vitamin E regeneration with it (Vit E) has been oxidised - Vitamin E complements vitamin C as a fat soluble antioxidant in cell membranes, while vitamin C protects compounds and structures in the fluid environment within cells and around them

Vitamin D deficiency

- Vitamin D deficiency can manifest in the following deficiency: - Rickets (children) - Condition where bones fail to calcify normally, causing growth retardation and skeletal abnormalities. Bones are weakened and bend -> "bowed legs" - Osteomalacia (adults) - Bones become soft, flexible, brittle and deformed from poor bone mineralisation - Osteoporosis (adults) - Develops from poor bone-acquisition during childhood/adolescence and bone loss of late adulthood

Vitamin D

- Vitamin D is a non-essential nutrient that acts like a hormone in the body - Two important forms of vitamin D for humans are: - Vitamin D2 or ergocalciferol (plant version) - Vitamin D3 or cholecalciferol (animal version) - Vitamin D3 can be synthesised from cholesterol in the skin and the amount is determined by the length and intensity of skin exposure - Activation occurs through the action of the liver and the kidneys - Calcitriol is the active form of vitamin D - A binding protein transports calcitriol to target organs (bones, kidneys and intestine)

Vitamin D toxicity - Toxicity disease is called hypervitaminosis D

- Vitamin D levels obtained from foods and produced by the skin are well within the safe limits. However, high-dose supplements may cause toxicity (especially for children) - Toxicity symptoms: - Elevated blood calcium concentration (hypercalcaemia) - Calcification of soft tissues (blood vessels, kidneys, lungs, heart and tissues around joints). Can cause death if calcification occurs in the major vessels of the heart or lungs - High blood level of calcium can cause frequent urination - Upper level = 80 μg/day for adults aged 19+

Vitamin D and bone health

- Vitamin D's role is to maintain blood concentrations of calcium (Ca) and phosphorus (P) - Vitamin D raises blood concentrations by: - Increasing mineral absorption from the GI tract - Mobilisation of calcium and phosphorous from bones into the blood - Reabsorption of minerals from the kidneys - Parathyroid hormone (PTH) and vitamin D work in concert to mobilise Ca from bone and conserve minerals from urine

Vitamin E

- Vitamin E family consists of two subgroups: tocopherols and tocotrienols - Of all the vitamin E family members, only α-tocopherol has vitamin E activity - All forms are absorbed in the small intestine, but the liver preferentially selects α-tocopherol with the help of the α-tocopherol transfer protein - The others are not converted to α-tocopherol in the body, nor are they recognised by the transport protein - The liver metabolises and removes the other vitamin E forms

Vitamin K: roles in the body

- Vitamin K is required for the synthesis of proteins involved in haemostasias (blood clotting) and bone metabolism - Bone metabolism - Vitamin K participates in metabolism of bone proteins, most notably osteocalcin. Without vitamin K, osteocalcin cannot bind to minerals to form bonds. Adequate vitamin K improves bone density, decreases bone turnover and protects against fractures - Blood-clotting - Prothrombin (an inactive protein made by the liver) is a vitamin K-dependent protein in the plasma that is directly involved in clotting. Without vitamin K, a haemorrhagic disease may develop

Micronutrients

- Vitamins and minerals do not provide energy and are known as micronutrients because the body needs them in smaller amounts - Vitamins are organic, essential nutrients that allow the body to obtain energy from carbohydrates, fats and proteins - Minerals are inorganic, essential nutrients that are found in the bones, teeth and body fluids - Most foods contain a mix of macro and micronutrients - Note: Water is an indispensable and abundant essential nutrients that participates in many life processes. As it is needed in a large supply each day (reactively) it should be referred to as a macronutrient - but non-energy yielding

Nutrition content claims and health claims

- Voluntary statements made by food businesses - On labels - In advertising about a food - E.g. - "A good source of fibre" - "Fibre from wholegrain to support healthy digestion"

Sources of water

- Water and other beverages plus foods such as fruit and vegetables - By-product of metabolism (ETC particularly) [metabolic water] - A daily intake of 1450-2800 millilitres of water is usually represented by: - Liquids 550-1500ml - Foods 700-1000ml - Metabolic water 200-300ml

Water and body fluids distribution

- Water is the medium in which all life processes occur - The bodies fluid environment actually consists of several distinct regions or compartments - Intracellular fluid within cells (high in potassium and phosphate), making up 2/3 of body water - Extracellular fluid makes up 1/3 of body water - Extracellular fluid consists of: - Interstitial or intracellular fluid - fluid between the cells that is high in sodium and chloride. Provides cells with required nutrients - Intravascular fluid - fluid within blood vessels i.e. plasma

The human body exhibits similar composition to foods

- Water makes up 2/3 of our body weight - Organic substances; protein, fat, carbohydrates and vitamins make up the bulk of the remaining body mass - Inorganic substances including minerals, make up a tiny portion only

Water soluble vitamins vs Fat soluble vitamins

- Water soluble vitamins - Absorbed directly into the blood - Transported by being dissolved into the blood - Storage of these is mostly minimal, but circulate through all water compartments of the body - Some vitamin B12 storage in the liver - Excess filtered from blood by the kidneys and removed in the urine - Unlikely to be toxic unless consumed in huge excess as supplements - Frequent doses every 1-3 days is required due to excretion losses - Fat soluble vitamins (A, D, E, K) - Absorbed initially in lymph within chylomicrons - Most are transported by protein carriers - Stored in fat cells or cells containing fat - Not easily excreted, tend to remain in the fat tissue - Some is removed via the bile (not very efficient to excrete fat soluble vitamins) - Unlikely to be toxic from food but very likely from excess supplements - Vitamin A could be toxic from excess liver consumption - Required in periodic doses days-weeks or even months, due to storage

Absorption in the small intestine

- Water-soluble nutrients and small products of fat digestion are released into the bloodstream - Fat-soluble vitamins and larger fats form chylomicrons and are released to the lymphatic system

Vitamins are categorised according to their solubility

- Water-soluble vitamins - generally not stored in the body for long periods (except B12) - Thiamin (vitamin B1) - Riboflavin (vitamin B2) - Pantothenic acid (vitamin B5) - Vitamin B6 - Folate - Vitamin B12 - Vitamin C - Water-soluble vitamins are absorbed into the mucosal cells depending on energy-requiring transport or binding of other molecules. These vitamins then directly enter the blood - Fat-soluble vitamins - these can be stored in fat and/or liver within the body for long periods of time and may pose an increased risk of toxicity - Vitamin A - Vitamin D - Vitamin E - Vitamin K

Inaccurate vs Accurate view of nutrient intakes

- We all differ in size, metabolism and genetics so the amount of any nutrient we need daily also varies between people - The RDI and AI are approximates only and in general there is a broad range around them that is generally sufficient and safe for most people - Very low intake = danger of deficiency - Low intake = marginal danger of deficiency - Average intake = RDI or AI - High intake = Tolerable upper intake level - Very high intake = Danger of toxicity

Quick changes in body weight are not simple changes in fat storage

- Weight gained or lost rapidly includes: - Some fat - Large amounts of fluid - And some lean tissue - Over the long term, weight lost is around 75% fat and 25% lean

Weight loss and regain

- Weight loss may increase LPL action (promoting fat storage) - It has been proposed that the body prefers to maintain weight at a 'set point' - I.e. after losing weight, the body tries hard to return to the original weight - The idea is that the 'set point' moves gradually over time for long-term weight loss

Adults in 2017-2018 were more likely to be overweight or obese than adults in 1995

- Weight management is a key component of good health - The prevalence of overweight and obesity is increasing - Overweight BMI 25-29.9 kg/m2 - Obesity BMI >30 kg/2

Health benefits of vegetarian diets

- Well-planned vegetarian diets can be nutritionally adequate (depending on the type and the age of the person consuming it) - May be associated with health benefit: - Weight control - possibly due to high fibre and low fat intakes - Lower blood pressure and reduced risk of hypertension - may be due to lower weight, more fruit and vegetables - Reduced heart disease - may be due to more - Mediterranean-style diet - diet tends to be high in fibre, polyphenols, antioxidants - Lower cancer - may be due to high intakes of fruit and vegetables, high fibre and no processed meat - Are these observations due to the food that is consumed or the food that is omitted from the diet?

Grain (cereal) Food group

- What is a serve of grain (cereal) food? - A standard serve is (500kj) or: - 1 slice (40g) bread - 1/2 medium (40g) roll or flat bread - 1/2 cup of cooked rice, pasta, noodles, barley, buckwheat, semolina, polenta bulgur or quinoa - 1/2 cup of cooked porridge - 2/3 cup of wheat cereal flakes - 1/4 cup of muesli - 3 (35g) crispbreads - 1 (60g) crumpet - 1 small (35g) English muffin or scone - Main distinguishing nutrients in this food group: - Carbohydrate - Protein - Iron - Dietary fibre - Thiamine - Folate - Iodine - Other significant nutrients in this food group: - Energy - Magnesium - Zinc - Riboflavin - Niacin - Vitamin E

Alcohol metabolism causes excess fat deposition

- When NAD becomes limited due to excessive use in metabolising alcohol, the TCA cycle slows and energy output decreases - Because the acetyl-CoA formed (from alcohol itself + 3 macronutrients) cannot be metabolised in the TCA cycle, it must exit the mitochondria as fatty acids and form fat - Some remains in the liver causing fatty liver disease and some is carried away to be stored in adipocytes around the body - Alcohol has the potential to disturb the normal functioning by removing NAD coenzyme molecules needed for transferring H atoms with high energy electrons to the ETC - The use of NADF by alcohol in the liver reduces NAD needed at 5 points in glycolysis and the TCA cycle. The result is acetyl-CoA must now form fatty acids then triglycerides and be stored - There is a lack of TPP coenzyme, due to alcohols effect on absorption of thiamine from food, thus slowing glycolysis and the TCA cycle even further

When a person overeats (feasting)

- When a person eats in excess of energy needs, the body stores a small amount of glycogen and much larger quantities of fat - Excess dietary carbohydrate is generally stored as glycogen first, then fat when glycogen storage capacity is full - Excess protein, above bodily needs is deaminated, the nitrogen is excreted as urea and the remainder stored as fat - Excess dietary fat is easily stored as body fat

Fasting

- When food availability was low we were able to draw on fat reserves to provide energy for our bodily functions and physical activity - This seldom occurs now as we have an abundant food supply and spend little energy obtaining it, hence we now accumulate fat constantly but seldom lose it - However if a period of food storage or fasting continues as in the past, using stored fat alone is not enough as fatty acids cannot make glucose, and glucose is needed for brain and CNS functioning - Other cells can efficiently breakdown fatty acids from fat reserves as an energy source, but the brain and nerve cells (and RBC) cannot - Glucogenic amino acids from proteins in muscle and organ tissue will be broken down for glucose production to allow the brain and CNS to keep functioning. This can be done for some time (days - weeks) - Glucose from protein eventually becomes limited and brain and CNS must use a further adaptation humans developed and that is the use of ketone bodies from fat for energy needs (note: ketogenic amino acids can also produce ketone bodies). This phase overlaps with the previous phase and can extend life for several weeks

When a person draws on stored (fasting)

- When food is unavailable to provide energy, the body draws on its glycogen and fat stores for energy - Use of glycogen which yields glucose can last a short period (hours - days), depending on how much is used by body cells compared with CNS use. Fat stores can fuel the bulk of body cells for a longer time (days - weeks), but not CNS cells - If the fast continues beyond glycogen depletion: - When glycogen stores are depleted, the body begins to break down its protein (muscle and lean tissue) to amino acids to synthesize glucose needed for the brain and CNS energy. In addition, the liver converts fats to ketone bodies, which serve as alternative energy source for the brain, thus slowing the breakdown of body protein - In the last stage of use of energy stores for survival: Glucogenic amino acids from body proteins will produce glucose (gluconeogenesis) to fuel CNS and body cells. Fat will produce fatty acids as previously, but now some will be converted to ketone bodies (energy compounds that can cross the blood-brain barrier) to fuel the CNS. Ketogenic amino acids from proteins can do the same

Feasting

- When food was available in abundance we ate as much as we could and stored the extra energy - Some energy was stored as glycogen, mainly in the liver and a little in muscle tissue - Most energy excess from food however was stored as fat cells (adipocytes) and some within general body cells such as muscles

White fat vs Brown fat

- White adipose tissue stores fat for other cells to use - Brown adipose tissue releases stored energy as heat - Important for newborns - Accounts for less than 1% of fat cells in adults - Recent research suggests 'browning' of fat cells (to brite/beige) increases energy expenditure and may reduce obesity

Finding nutrition information

- Who is qualified to speak on nutrition? - Nutrition researchers - Dietitians - Nutritionists - Medical practitioners - Scientific journals e.g. - Nutrition and Dietetics (Aust) - American Journal of Clinical Nutrition - European Journal of Clinical Nutrition - Journal of Nutrition - Nutrition Reviews etc. - Internet - Pubmed should be the primary source of new nutrition research information - Credible organisation websites i.e. Nutrition Australia, Better Health Channel - We aware of private websites pushing sales or personal opinions or lobby group views

Vitamin B7 (Biotin) Food sources

- Widespread in many foods such as liver and green leafy vegetables and small amounts can also be made by GI bacteria

Disordered eating in athletes

- Young athletes/dancers may restrict energy intake to: - Improve performance - Improve aesthetic of their performance (e.g. gymnastics, ballet) - Meet weight guidelines of their sport (e.g. wrestling) - Likely to negatively impact on their performance and health - Increases risk of disordered eating (restrictive diets, ritualised eating patterns, rigid food avoidance leading to nutritional deficiencies and medical problems) -> Body dysmorphia (e.g. athletes thinking they need to bulk up and taking excessive protein and/or steroids) + Amenorrhoea (periods stop) -> Impaired bone health (leading to osteoporosis) and stress fractures

Zinc (Zn2+)

- Zinc is required as a cofactor for many enzymes - Generally found in conjunction with proteins in foods - All cells in the body contain zinc; most found in bone, prostate gland and eyes - Muscles make up a large portion of the body zinc though not individually concentrated in zinc - Not easily released into the body so frequent or constant intake is required - Involved in immune function, growth and development, essential to the eyes to convert retinol to retinal, for production of retinol binding protein (RBP) for transport and metabolism of vitamin A - Also essential for taste, wound healing, sperm production and foetal development

Which food provides the most soluble fibre?

1 cup baked beans

What is a standard drink?

1 standard drink = 10g pure ethanol

What are the stages of liver deterioration?

1. Fatty liver 2. Fibrosis 3. Cirrosis

Steps involved in iron absorption

1. Iron in food is absorbed and stored in intestinal wall cells, bound to mucosal ferritin (a protein) - The intestinal mucosal cells are rich in iron as the transport process from digested food to the blood is slow. Hence loss of intestinal lining cells removes iron from the body 2. Transferrin carries the iron from intestinal mucosal cells into the blood 3. Transferrin then transports iron to the rest of the body 4. Most iron ends up in bone marrow for RBC production 5. Excess iron is stored in proteins (ferritin and haemosiderin). This is to protect the body from the damaging effects of free iron 6. Bodily iron status can be determined by blood ferritin levels

Standard conversions of energy composition of macronutrients

1g carbohydrates = 17kj 1g fat = 37kj 1g protein = 17kj 1g alcohol = 29kj

Adequacy is particularly important for which subpopulations?

Growing children, adolescents, pregnant women, breast-feeding women and older people

How many known important trace minerals are there?

12 - As knowledge of biological systems increases this list will likely be extended

What compounds do pancreatic juice contain?

HCO3- and digestive enzymes

How much sun exposure is needed per week to get your vitamin D levels during a Melbourne winter (May-August)?

2-3 hours

Why do some women only experience iron deficiency symptoms during menstruation?

Blood loss facilitates iron loss, therefore at first when an individual's iron levels are only mildly deficient, they'd only experience iron deficiency symptoms during menstruation

The human body contains an estimated 30000 different kinds of proteins that form based on the way...

20 amino acids can combine

What are the current recommendations for total fat intake?

20-35% of total energy consumed

How much fibre does the average Australian eat?

20g

Of the 10 leading causes of illness and death, how many are associated directly with nutrition?

4

How much energy does 1kg body fat contain?

A 'classic rule' states that one kg of body fat contains approx. 30000kj of energy

What is a 'functional fibre'?

A 'functional' fibre' is one that is extracted from plants and added to food for some health benefits

Which potentially harmful macronutrient can fibre displace in a high-fibre diet?

Fat

Vitamin B1 (Thiamine) Function

A coenzyme in the catabolism of sugars and amino acids - Main function is in energy metabolism as an integral part of the coenzyme TPP (thiamin pyrophosphate) involved in the conversion of pyruvate to acetyl CoA - TPP facilitates the removal of a carbon group from pyruvate to yield acetyl-CoA (2 carbons) and a carbon dioxide. TPP is also involved in a later step in the TCA cycle in which a carbon group is removed from a 5C compound

Estimated Average Requirement (EAR)

A daily nutrient level estimated to meet the requirements of half the healthy individuals

In a fasting state what is a normal range for blood glucose?

5-6 mmol/L

If you were to exercise continuously, about how long would glycogen stores last?

A fww hours

What are the current recommendations for saturated total fat intake?

8-10% of total energy consumed

What is the recommended range for LDL-cholesterol?

<1.8 mmol/L

What is the recommended range for triglyceride levels?

<2.0 mmol/L

What is the recommended range for total cholesterol for people 20 yrs +?

<4.0 mmol/L

What is the recommended range for HDL-cholesterol?

>1.0 mmol/L

Approximately how many kilograms of sugar does the average Australian adult consume each year?

42

Acceptable Macronutrient Distribution Ranges (AMDR)

45-65% energy from carbohydrates, 20-35% energy from fats and 15-25% energy from protein

What is the minimum daily amount of dietary carbohydrate necessary to spare body protein from excessive breakdown?

50-100g

Proteins that consist of two or more chains assembled into a large 3D structure are said to display...

A quaternary structure

Discretionary choices Food group

A serve of discretionary choices provides about 500-600 kilojoules: - 2 scoops of ice cream - 2 slices of processed meats, salami or mettwurst - 2 thin regular sausages - 1/2 snack size packet of salty crackers or crisps - 2-3 (35g) of sweet plain biscuits - 1 (40g) doughnut - 1 slice (40g) plain cake/small cake-type muffin - 5-6 (40g) sugar confectionary/small lollies - 1 tbslp (60g) jam or honey - 1/2 bar (25g) chocolate - 2 tblsp (40g) cream - 1 tblsp (20g) butter - 1 can (375ml) soft drink (sugar-sweetened) - 1/4 pie or pastie (60g) commercial meat pie or pastries - 12 (60g) fried hot chips - 200ml wine - 60ml spirits - 600ml light beer - 400ml standard beer

Unsaturated fats/oils/spreads Food group

A standard serve: - 10g polyunsaturated spread - 10g monounsaturated spread - 7g monounsaturated or polyunsaturated oil e.g. canola or sunflower oil - 10g tree nuts or peanuts or nut pastes/butter - Fats provide energy and some provide essential unsaturated fatty acids and fat-soluble vitamins such as vitamin A and E

Experimental design matches people for

Age Sex BMI Diet Health Habits etc

Which item is contained in an amino acid?

An acid group

What foods are considered complete proteins?

Animal protein - Chicken - Eggs - Cheese - Tofu

What does BMI indicate?

BMI is a numerical value based on an individual's weight and height that indicates whether one is in a healthy weight range or if he/she is underweight, overweight or obese

What is the primary means of degradation of soluble fibres?

Bacterial enzymes in the large intestine

Functions of protein

Brain cells, muscle, skin, hair and nails are just some of the body parts that are protein-based. Estimates suggest that about half of the body's dry weight is made up of protein

Non-dairy calcium sources:

Broccoli Figs Spinach Sesame seeds Orange Cabbage Seaweed Bok choy

Where to get help for eating disorders

Butterfly foundation - Butterfly.org.au

How is an an individual's' recommended body mass calculated?

By taking the midpoint of the healthy weight range

What is calcium balance?

Calcium balance is the difference between the amount of calcium an organism ingests every day and how much it loses, principally through measured excreta, but also through non-measured routes such as shed hair, skin, nails, sweat, and other body secretions. Vitamin D helps the body absorb calcium so if you are deficient in Vitamin D, even if your calcium intake is enough, you won't absorb calcium.

What are carbohydrates?

Carbohydrates are the sugars, starches and fibres fund in fruits, wholegrain, legumes, vegetables and milk products

Which individual is likely to possess the least amount of nutrition training, and to have gotten his or her degree from an 'alternative' educational program?

Certified nutritionist

What is the full name of the co-enzyme termed CoA?

Coenzyme A

Most B group vitamins function as...

Coenzymes in metabolic processes, particularly in energy metabolism pathways

What is the name of the reaction forming a bond between amino acids

Condensation

Triglyceride formation

Condensation reaction between glycerol and three fatty acids

What is an example of complementary proteins?

Cornbread and kidney bean chilli

Vitamin B9 (Folate) Deficiency during pregnancy

Deficiency in pregnant women can lead to birth defects: - Neural tube defects - Cause is uncertain, but women consuming excess levels of folate have a lower probability of having a baby with a neural tube defect - Neural tube is embryonic tissue of the CNS - Defects in the formation of this tissue lead to spina bifida and anencephaly (portion of brain, skull and scalp does not form) Critical periods in foetal development: - Extra folate during pregnancy, particularly the first trimester has resulted in decreases cases of Spina Bifida and neural tube defects in general - Most countries now fortify foods with folate for the benefit of growing children and pregnant women - Also pregnant women are usually advised by doctors to take supplemental folate during pregnancy, particularly the first trimester, which appears to be a "window of opportunity" (critical period) for neural development that cannot be fully recovered from later

Vitamin B3 (Niacin (nicotinic acid), Nicotinamide) Deficiency and Toxicity

Deficiency: - Deficiency of B3, along with a deficiency of tryptophan (some niacin can be made by some proteins), causes: - Pellagra (dermatitis, insomnia, weakness, mental confusion and diarrhea). - In the dermatitis of pellagra, the skin darkens and flakes away as if it was sunburned - The dermatitis is symmetrical and occurs only on parts of the body exposed to sunlight - In advanced cases, pellagra may lead to dementia and death (the 4 D's (dermatitis, diarrhea, dementia and death)) Toxicity: - Symptoms: - Painful, hot, tingling, skin flush, - Hives and rash, - Excessive sweating, - Blurred vision, - Liver damage, - Diarrhoea, - Nausea, - Vomiting, - Ulcers, - Dizziness, - Fainting - Low blood pressure - Impaired glucose tolerance - Large doses of niacin have a pharmacological effect on the nervous system, blood lipids and blood glucose - Large doses have been used in lowering blood cholesterol levels - In the nicotinic acid form large doses can dilate capillaries in the skin causing a hot tingling flush - Recommended intakes - Niacin intake is calculated in niacin equivalents (NE) as some niacin is made in vivo as well as consumed in the diet - E.g. the amount of niacin in food plus that made from tryptophan (1/60 tryptophan) - Nutrient reference values for Niacin are: - RDI = 16 mg/day for men (>19 yrs) - RDI = 14 mg/day for women (>19 yrs) - RDI = 18 mg/day for women (pregnant) - RDI = 17 mg/day for women (lactating)

Vitamin B7 (Biotin) Deficiciency

Deficiency: - Extremely rare due to the small amount required and its availability in many foods - Deficiency can be induced by massive consumption of raw egg whites (contains the binding protein avidin, which prevents absorption of biotin) - Symptoms: - Cosmetic issues in adults, such as decreased hair and nail growth, - Nausea - Loss of appetite - Depression - fatigue - Dry skin - May lead to impaired growth and neurological disorders in infants - Toxicity symptoms - None known - Nutrient reference values for Biotin are: - AI: 30 ug/day for men (>19 yrs) - AI: 25 ug/day for women (>19 yrs) - AI: 30 ug/day for women (pregnant) - AI: 35 ug/day for women (lactating)

If an individuals' protein intake (%TE) is not within the AMDR, how could this be improved, maintaining the same total energy intake?

Replace some fat intake with protein intake

Estimated Energy Requirement (EER) calculation

EER = PAL x BMR

What are the health implications of consuming too much fat?

Easy to overeat kJ, as fat is very energy dense. (double that of proteins and carbohydrates). This results in weight gain, and potentially obesity which is a risk factor to chronic disease.

How could individuals in the general population decrease sodium intakes?

Eat more fresh fruit and vegetables (low in sodium) and decrease consumption of processed foods (high in sodium)

What vitamin gives rise to the co-enzyme THF (Tetrahydrofolate)?

Folate (vitamin B9)

What are Rugae?

Folds and wrinkles of the stomach that allow it to stretch greatly

What is the full name of the co-enzyme termed FAD?

Flavin adenine dinucleotide

What is the full name of the co-enzyme termed FMN?

Flavin mononucleotide

Tertiary and quaternary protein structure of haemoglobin

Four highly folded polypeptide chains form the globular haemoglobin proteins

What is the sweetest tasting simple carbohydrate in the diet?

Fructose

Gluconeogenesis is a term that describes the synthesis of:

Glucose from a non-carbohydrate substance

Circulatory system of the digestion system goes through the liver

Heart -> arteries -> capillaries (intestines) -> portal vein -> liver -> capillaries (liver) -> hepatic vein -> heart - The liver: - Removes toxic substances that might cause harm and prepares waste products for excretion - Liver is susceptible to poisons, viruses (hepatitis), drugs (i.e. alcohol and barbiturates), toxins and contaminants (i.e. pesticide residues, mercury)

Almost 70% of the lipid in coconut oil is dangerous

High in hypercholesterolemic fatty acids such as Lauric acid, Myristic acid and Palmitic acid

Increasing the amount of complex carbohydrates and decreasing the amounts of simple carbohydrates in the diet results in a diet that is...

Higher in fibre

What is the sequence of fat digestion and absorption?

Large fat globules -> small fat droplets -> fatty acids and glycerol -> absorption

Milk, yoghurt, cheese and/or alternatives Food group

How much is a serve? - A standard serve is (500-600kj): - 1 cup (250ml) of fresh, UHT long life, reconstituted powered milk or buttermilk - 1/2 cup of evaporated milk - 2 slices (40g) of hard cheese, such as cheddar - 1/3 cup of ricotta cheese - 3/4 cup of yoghurt - 1 cup of soy, rice or other cereal drink with at least 100mg of added calcium per 100ml - Main distinguishing nutrients in this food group: - Calcium - Protein - Riboflavin - Vitamin B12 (animal foods only) - Other significant nutrients in this food group: - Energy - Fat - Carbohydrate - Magnesium - Zinc - Potassium - The following foods contain about the same amount of calcium as a serve of milk, yoghurt or cheese: - 100g of almonds with skin - 60g of sardines, canned in water - 1/2 cup (100g) of canned pink salmon with bones - 100g of firm tofu (check the level as calcium levels vary)

Lean meat and poultry, fish, eggs, nuts and seeds and legumes/beans Food group

How much is a serve? - A standard serve is (500-600kj): - 65g of cooked lean red meats such as beef, veal, pork, goat or kangaroo - 80g of cooked lean poultry such as chicken or turkey - 100g cooked fish fillet or one small can of fish - 2 large (120g) eggs - 1 cup (150g) of cooked or canned legumes/beans such as lentils, chickpeas or split peas - 170g of tofu - 30g of nuts, seeds, peanut or almond butter or tahini or other nut or seed paste - Main distinguishing nutrients in this food group: - Protein - Iron - Zinc - Vitamin B12 (animal foods only) Long chain omega 3 fatty acids - Other significant nutrients in this food group: - Dietary fibre (plant foods only) - Energy - Essential fatty acids - Niacin - Vitamin E (seeds, nuts)

Cell structure and function

Human cells consist of: - Fluid-filled sac contained within a thin skin called the cell membrane - The membrane has a double phospholipid layer embedded with protein and cholesterol particles - Cytoplasm is a fluid environment containing organelles and chemical substances including molecules from the breakdown of macronutrients - The initial process of energy metabolism (glycolysis) involves the formation of pyruvate from glucose and occurs in the cytoplasm under anaerobic conditions - Mitochondria are folded membrane organelle structures containing enzymes involved in the tricarboxylic acid cycle (TCA) and the ETC - Reactions of the TCA cycle are often called Krebs cycle and occur in fluid of the mitochondria - Final stage of energy release occurs on the internal walls of the mitochondria. Protein structures of the ETC are found here

Carrot propaganda

In WWII, many advertisements encouraged the consumption of carrots to help see in the dark to help sweeten foods in the absence of sugar

Predominant Vitamin imposters

In some cases of supposed new vitamins, the body makes its own supply or does not require the compound at all (e.g. para-amino benzoic acid: PABA) - The predominant vitamin imposters are: - Hesperidin (vitamin P) - Pyroloquinoline quinone - Insufficient information is available so far to state that PQQ is a vitamin for mammals, although PQQ may be an important biological factor - Orotic acid - Once believed to be part of the vitamin B complex and called vitamin B13, but it is now known that it is not a vitamin but is manufactured in the body by intestinal flora - Lipoic acid - Humans biosynthesize lipoic acid and it is not a required vitamin - Vitamin O (oxygenated sea water) - Pangamic acid (vitamin B15) - It is not a true vitamin, has no nutritional value, has no known use in the treatment of any disease and has been called a "quack remedy"

Where does the TCA cycle occur?

In the Mitochondrial fluid space (Aerobic)

Where is the energy contained in these macronutrient molecules?

In the chemical bonds (pairs of electrons) - During catabolic metabolism, macronutrient molecules are broken down and energy is released - This released energy is used to fuel other chemical reactions and physical activities including the building of new molecules

Where does Glycolysis occur?

In the cytosol (anaerobic)

Where are disaccharide enzymes found?

In the small intestine Disaccharide enzymes hydrolyse disaccharides into monosaccharides

Are vegetarian diets healthier than omnivorous diets?

It depends what you are comparing - Typical Australian (junk-food) diet - Well-chosen vegetarian diet - Unbalanced vegetarian diet - Well-balanced ADG recommended omnivorous diet Any comparison depends on the whole diet

How is soluble fibre defined?

It partially dissolves in water

What is the role of the oesophageal sphincter?

It relaxes to let food enter the stomach

What do sugar alcohols provide?

Kilojoules (energy)

What energy units does Aus use?

Kilojoules (kJ), in the USA they use kilocalories (Calories)

The 6 nutrient classes

Lipids Proteins Carbohydrates Water Vitamins Minerals

Osmosis is the movement of water from an area of...

Low solute concentration to an area of high solute concentration. The force that causes this movement is called osmotic pressure

What is a product of the chemical digestion that occurs in the mouth?

Maltose

What foods provide protein?

Meat, milk, eggs, legumes and many grains and vegetables

Which foods are rich in protein and might feature largely in a high- protein diet?

Meats, legumes, wholegrain, eggs, green vegetables, dairy products

Which gender is more likely to be overweight or obese?

Men are more likely to be overweight or obese than women

What vitamin gives rise to the co-enzyme NAD (Nicotinamide adenine dinucleotide)?

Niacin (vitamin B3)

Why is osteoporosis more common in women than men?

Menopauses causes a sharp decrease in bone mass - Loss of height is seen particularly in women as they age, due to bone loss involved with osteoporosis - Men would also suffer osteoporosis (and some do) but because men in 'general' eat more food (hence calcium) and do more physical work than most women, thus they tend to build up high bone mass in younger years

What are Essential nutrients?

Nutrients that must be obtained from food, cannot be made in the body, ~40 known

What is Nutrition?

Nutrition is the science of foods and the nutrients they contain and their actions within the body (including ingestion, digestion, absorption, transport, metabolism and excretion). It also includes the social, economic, cultural and psychological implications of food and eating

What is hyperplastic obesity?

Obesity caused by an increase in the number of fat cells

What is hypertrophic obesity?

Obesity caused by an increase in the size of fat cells

Where does the electron transport chain (ETC) occur?

On the Mitochondrial inner membranes (Aerobic)

When a protein is denatured, its primary structure is maintained, but...

Other aspects of its structure are disrupted

What vitamin gives rise to the co-enzyme CoA (Coenzyme A)?

Pantothenic acid (vitamin B5)

What food is an example of the best source of energy for endurance athletes?

Pasta

Which digestive enzyme needs a highly acidic environment to function?

Pepsin (breaks down proteins)

Which type of interaction is not directly involved in maintaining a protein's tertiary structure?

Peptide bonds

What propels food down the oesophagus to the stomach?

Peristalsis

What is Food?

Products derived from plants or animals that can be consumed to yield energy and nutrients for the maintenance of life and growth and repair of tissues

What best describes the structure of pepsin?

Protein

Roles of protein in the body

Protein is constantly being broken down and new types are synthesised in the body for: - Structural purposes - Enzymes - Hormones - Fluid balance in the body - Acid-base balance - Antibodies for immune function - Transport - Source of energy and glucose - Blood clotting

Protein - Enzymes facilitate chemical reactions

Proteins catalyse chemical reactions including anabolic enzymes and catabolic enzymes

Protein - Source of glucose and energy

Proteins will be sacrificed to provide energy and glucose during times of starvation or insufficient carbohydrate intake

What vitamin gives rise to the co-enzyme PLP (Pyridoxal phosphate)?

Pyridoxal (vitamin B6)

What is the full name of the co-enzyme termed PLP?

Pyridoxal phosphate

Which activity is more effective in preventing the formation of dental caries than restricting the intake of sugary foods?

Regular tooth-brushing and flossing

Lab animal and in vitro studies

Researchers feed animals special diets that provide or omit specific nutrients and then observe any changes in health

What vitamin gives rise to the co-enzyme FAD (Flavin adenine dinucleotide)?

Riboflavin (vitamin B2)

What vitamin gives rise to the co-enzyme FMN (Flavin mononucleotide)?

Riboflavin (vitamin B2)

Zinc is required to make insulin in the pancreas

Role in glucose metabolism

Sterols - cholesterol in the body

Roles of cholesterol - Starting material for bile acids, sex hormones, adrenal hormones and vitamin D - Structural component of cell membranes - Liver produces 800-1500mg cholesterol per day (much more than we eat) - Atherosclerosis is a disease that causes heart attacks. It occurs when oxidised cholesterol forms deposits in the artery wall

Clinical trials (Human intervention)

Scientists ask people to adopt a new behaviour (e.g. eat a citrus fruit, take vitamin C or exercise daily) and then observe any changes in health

What are dextrins?

Short chains of glucose units that result from starch breakdown

The A, B, C, D, M and V of diet planning

Six basic principles of diet planning: - Adequacy - Balance - Kilojoule (energy) - Control - Nutrient Density - Moderation - Variety

What valves control the movement of food in and out of the stomach?

Sphincters (oesophageal and pyloric)

Which compound undergoes chemical digestion in the mouth?

Starch

What compound continues to be broken down in the small intestine?

Starch (via amylase)

How does peak bone mass influence the risk of osteoporosis later in life?

Starting with more bone mass (higher peak bone mass) will ensure that we have enough calcium in our bones to last a lifetime and lowering the risk of osteoporosis later in life

Which element is found in certain amino acids?

Sulphur

Recommended Dietary Intake (RDI)

The average daily dietary intake level sufficient to meet the nutrient requirements of nearly all healthy individuals in a particular life stage and gender group

Estimated Energy Requirement (EER)

The average dietary energy intake that will maintain energy balance in a person with a healthy body weight and level of activity

What happens to insoluble fibre when you eat it?

The fibre passes through the gastrointestinal tract undigested

What is Diet?

The foods and beverages a person consumes

Upper Level of Intake (UL)

The highest average daily nutrient intake level likely to pose no adverse health effects to almost all individuals in the general population. As intake increases above the UL the risk of adverse effects increases

Vitamin C Food sources

The main dietary sources of vitamin C are fruits and vegetables in particular citrus, berries, cabbage type vegetables, dark green vegetables, strawberries, watermelon, peppers, kiwi fruit, tomatoes etc.

What is metabolism?

The process by which nutrients are broken down to yield energy or are rearranged into body structures (catabolism and anabolism)

What is Absorption?

The process by which nutrients pass through the walls of the digestive system into the blood

What is Digestion?

The process by which the composition of food is broken down in order to get energy and nutrients to fuel the body

What is catabolism?

The process of breaking down molecules E.g. glycolysis

What is anabolism?

The process of building up molecules E.g. glycogenesis

What is Excretion?

The process of removing waste and excess water from the body

What is Ingestion?

The process of taking food, drink or other substances into the body by swallowing

What happens to fat cells with negative energy balance?

The size of the fat cells decreases, but not the number

Digestive enzymes are not defined by...

Their hydrophobic properties

What is the main function of the villi in the small intestine?

They absorb nutrients into the bloodstream

Calcium availability of spinach and sweet potatoes...

They both have low calcium availability

What vitamin gives rise to the co-enzyme TPP (Thiamine Pyrophosphate)?

Thiamin (vitamin B1)

What is the full name of the co-enzyme termed TPP?

Thiamine Pyrophosphate

Which of the following is not an example of a functional food?

Tomatoes rich in natural lycopene

What are the micronutrients?

Vitamins and minerals

What measurement is the most practical indication of fat distribution and central obesity?

Waist circumference

Which component of food is normally absorbed in the large intestine as well as the small intestine?

Water

What are the macronutrients?

Water Proteins Carbohydrates Lipids All contain energy except water

How might a trainer's high protein diet be detrimental to their goal of gaining muscle mass?

Weight loss: - Increased dietary protein couples with increased water loss through urine - Protein-rich foods are highly satiating, causing one to eat less

Fruit Food group

What is a serve of fruit? - A standard serve is about 150g (350kj) or: - 1 medium apple, banana, orange or pear - 2 small apricots, kiwi fruits or plums - 1 cup of diced or canned fruit (no added sugar) - Or only occasionally: - 125ml (1/2 cup) fruit juice (no added sugar) - 30g dried fruit (e.g. dried apricot halves, sultanas) - Main distinguishing nutrients in this food group: - Vitamin C - Dietary fibre - Other significant nutrients in this food group: - Carbohydrate - Folate - Beta-carotene - Potassium

Vegetables and legumes/beans food group

What is a serve of vegetables? - A standard serve is about 75g (100-350kj) or: - 1/2 cup of cooked green or orange vegetables (e.g. broccoli, spinach, carrots or pumpkin) - 1/2 cup of cooked dried or canned beans, peas or lentils - 1 cup of green leafy or raw salad vegetables - 1/2 cup of sweet corn - 1/2 medium potato or other starchy vegetables (sweet potato, taro or cassava) - 1 medium tomato - Main distinguishing nutrients in this food group: - Beta-carotene and other carotenoids - Vitamin C - Folate - Dietary fibre - Other significant nutrients in this food group: - Carbohydrate (potato, sweet potato, sweet corn and legumes) - Magnesium - Iron - Potassium

What is a positive nitrogen balance?

When nitrogen consumption is greater than excretion

The Lancet Global Burden of Disease Study recently measured the health effects (mortality and morbidity) of dietary risks in 195 countries between 1990-2017

Where did low intake of whole grains sit on the list of dietary factors related to mortality? - The second greatest risk factor

Vitamin B5 (Pantothenic acid) Food Sources

Widespread in foods, particularly in organ meats, meat, fish, poultry, wholegrain cereals, broccoli, mushrooms, avocados and legumes

Recommended dietary intake for Fibre

Women: 25g/day Men: 30g/day

Why is vitamin D sometimes called the 'sunshine vitamin'?

Your skin makes vitamin D when it gets sunlight - More than 80% of vitamin D in our body comes from sunlight - Sun protection factors (SPF) >8 prevent vitamin D synthesis - The amount of exposure to sunlight (arms, face and hands) varies according to the time of year and location