NUTR 306 Mid term

GI anatomy

-Flexible and muscular tube with a continuous inner space (lumen) -Extends from mouth to anus -~100 trillion microbes inhabit the GI trace ---Bacteria, viruses, fungi , protozoa, archaebacteria, etc. ---Role in health, metabolism, and disease ---Differences in obese versus non obese people ---influences by early life exposures and diet

Disaccharides

-Simple carbs -Pairs of monosaccharides (all containing glucose) -Condensation ---Links two monosaccharides together ---Releases water as by-product -Maltose ---glucose + glucose ---produced by a breakdown of starch ---involved in fermentation ---aka malt sugar -Sucrose ---glucose + fructose ---sweetest disaccharide ---Most abundant disaccharide found in nature ---aka table sugar -Lactose ---glucose + galactose ---Found in milk and milk products ---aka milk sugar

Fat absorption

-Small molecules are absorbed and go directly into bloodstream -Large molecules (micelles) are absorbed but get broken down and reassembled into: ---Chylomicrons = TGs + cholesterol + phospholipids + proteins -Chylomicrons released into lymphatics ---Bypass the Liver (allows other organs accessibility) ---Released into the circulation later on

waist circumference

-Strong predictor of disease risk -Based on fat in the abdominal area -Doesn't differential fat types or specific location

Portion size

-Target: 1 serving size/eating occasion -read 'serving sizes' on packages -estimate with hand portions ---Fingertip: ~1 tsp ---Front of closed fist: ~1/2 cup ---Bottom of closed fist: ~1 cup ---Palm: ~3-4 oz ---Thumb: ~2 tbsp

Definition of Plant-based diet

A diet containing mostly foods derived from plants, specifically whole foods from vegetables, grains, buts, seeds, legumes, & fruits, + high quality animal source foods

The 'Right' Plant-based diet

A diet containing mostly foods derived from plants, specifically whole foods from vegetables, grains, buts, seeds, legumes, & fruits, + high quality animal source foods

DRI

Dietary Reference Intake -NOT food recommendations -Reduce deficiencies -Reduce risk for chronic disease -Recommendations apply to healthy people -(EAR, UL, AI, RDA)

Protein Quality

Digestibility -Proteins must be digested before they can provide AAs to the body -Digestibility depends on the source and other foods eaten with protein ---Animal proteins: 90-99% digestible ---Plant proteins: 10-90% digestible AA composition -For protein synthesis, dietary protein must supply all 9 essential AAs in proportions needed by humans ---Animal proteins: generally provide the most complete complement of AAs and are sometimes referred to as 'Complete proteins' ---Plant proteins: tend to be limiting in one or more essential AA and are sometimes referred to as 'Incomplete Proteins'

Mouth (upper digestive tract)

Digestion starts here -Chewing to break food apart and mixing with saliva eases swallowing -Blotus - Food that has been chewed and swallowed Five basic taste perceptions: -sweet -sour -bitter -salty -umami

Macronutrients vs Micronutrients

Macronutrients - Carbs, lipids, proteins. Required in relatively large amounts. Energy yielding. Micronutrients - Vitamins and minerals. Needed in relatively small amounts. Non-energy yielding.

Health benefits of mono and polyunsaturated fatty acids

Monounsaturated fats: -increase HDL (good) -decrease LDL (good) -decrease TG (good) -Omega-9 fatty acids ---aleic non-essential Polyunsaturated fats: -Increase HDL (good) -decrease LDL (good) -Decrease tG (good) -Omega 3 fatty acids ---Alpha-linolenic acid - essential ------DHA - conditionally essential ------EPA - conditionally essential -Omega 6 fatty acids ---linolenic acid - essential

Protein Digestion

Mouth -Nothing Stomach -Small amount of digestion (~10-15%) -HCI & inactive enzyme (pepsinogen) Small intestine -Most protein digestion occurs here (85-90%) ---Pancreas & small intestine => proteases & peptidases Large Intestine -Nothing

carb absorption

Move the small molecules broken down by digestion our of the GI and into the vascular system

Absorption

Movement of smaller molecules out of the digestive tract and into the body via 2 different 'vascular systems' -Esophagus and stomach --- No absorption -Small Intestine --- Majority of absorption of nutrients (except water) -Large Intestine ---Majority of absorption of water

DRIs and DGAs for Lipids

No RDA or AI for Total Fat: insufficient evidence -AMDR (lower range) set to provide adequate consumption of: ---energy, Essential FAs, & Fat-soluble vitamins No UL => fats aren't toxic, but... -AMDR (upper range) set to prevent fat excess = obesity & CVD Regarding polyunsaturated fats, both Omega 6s and 3s have AI, but no UL

Protein Absorption

Peptides can either be: 1.) broken down into smaller peptides or AAs by enymes 2.) transported into the intestinal cells ---Di and Tripeptides are transported without energy ---AA transporters (like glucose) require energy -Inside the cell, di and tripeptides can be broken down into AAs -Many AAs are used by small intestine -Unused amino acids transported to liver ---Some AAs bypass liver (BCAAs)

TCA cycle & electron transport

TCA cycle -Final common metabolic pathway for energy nutrients -Circular pathway (one way) ---Acetyl CoA (2-carbon compound) travels one way and releases: ------Two carbon dioxide molecules ------One CoA enzyme ------Hydrogen atoms and the electrons => carried off by coenzymes to electron transport chain ---Oxaloacetate: 4-carbon compound made primarily from pyruvate ------Needed to initiate first step and synthesized in last step of cycle ------Must be available for acetyl CoA to enter cycle Electron transport chain -Captures energy bonds of ATP -Series of proteins ---Electron "carriers" mounted in sequence ---Inner membrane of mitochondria -Coenzymes deliver electrons ---From TCA cycle, glycolysis, and fatty acid oxidation ---Electrons passed to the next carrier, and next carrier, and next carrier, until... ---Oxygen is reached at the end of chaine ------Oxygen accepts electrons, combines with H atoms = H2O released. ---ATP synthesis powered by H ions: ------Pumped out of inner compartment, then rush back in

Six classes of nutrients

carbohydrates, lipids, proteins, vitamins, minerals, water

Energy balance

energy intake = energy expenditure

Non-energy yielding nutrients

vitamins, minerals, water

Proteins

~50% of cell content -Do most cellular work ---Required for structure, function, and regulation of organs, tissues, and body systems ---Support tissue growth, repair, and maintenance

energy yielding nutrients

Carbs (4 kcal/g) Fats (9 kcal/g) Proteins (4 kcal/g) Excess energy is stored as fat.

Protein Metabolism

Fed State -Provide AAs for functional needs, including muscles -Supplies 10-15% of the body's faily energy needs -Excess of AAs: ---Converted to glucose => glucagon ---Converted to ketone bodies => fat Fasted State -Breaks fown body protein to provide AAs for: ---Functional needs, not including muscles ---Creation of glucose for energy ---Creation of ketone bodies for energy Pro Turnover -Nitrogen Balance: Nitrogen in vs Nitrogen out -used for protein requirements ---(-) Nitrogen balance: Nitrogen out > Nitrogen in -------Severe stress: starvation, burns, infections, fever, injuries ------Leads to muscle wasting ---(+) Nitrogen Balance: Nitrogen in > Nitrogen out ------Occurs with increased dietary protein ------May be beneficial for muscle gains, etc Biproducts -Ammonia Production ---Generated as a result of Amino Acid Metabolism ---Toxic compound & needs elimination ---Liver can convert it to Urea ---Kidneys filter urea out of blood and into urine

Amino acid metabolic pathways

First step: deamination -N-containing amino group is lost -Produces ammonia + keto acid Amino Acid => energy pathway -Converted to pyruvate (glucogenic) -Converted to acetyl CoA (ketogenic) -Enter TCA cycle directly (glucogenic) Amino Acids => glucose -When carbohydrates are unavailable

Rectum

Gathers stool

Glycolysis (conversions of glucose to pyrucate)

Glucose => Pyruvate -"Glucose-splitting" -One glucose molecule becomes 2 pyruvate molecules -Hydrogen atoms (H+) carried to electron transport chain Pyruvate can be converted back to glucose if needed -Primarily by liver cells (~kidneys) -Process is similar to glycolysis reversal

Glycerol and fatty acid pathways

Glycerol -Can easily be converted into glucose or pyruvate (and acetyl CoA after Pyruvate) Fatty Acids -Cannot be used to synthesize glucose -Fatty acid oxidation ---Fatty acids dismantled 2-carbon units at a time ---2-carbon compounds join with CoA => acetyl CoA ---As carbons break off, associated hydrogens and electrons carried to electron transport chain

Carb metabolism

Glycogen is glucose as stored energy -made when blood glucose is high ---3/4 is stored in muscles ---1/4 is stored in liver (1 days worth) ---tiny amount stored in brain (few min worth - emergency use) -broken down when blood glucose is low (between meals/overnight) ---muscles - keeps it for itself (to be used during exercise) ---liver - as needed for the rest of the body Brain => Primary user of glucose -Uses ~60% total glucose -Power transmission of nerve impulses; synthesize neurotransmitters -Can use ketones (when needed) Inadequate amount of CHO -Fat molecules are broken down and form ketone bodies ---Alternative fuel during severe energy deficits/starvation/low-carb 'ketogenic' diets ---Disrupts body's acid-base balance ---Excessive ketones => accumulate in blood => ketosis => ketoacidosis -Cells can convert amino acids (from protein) => glucose -Body needs ~60-100 g of CHO/day to: ---Prevent ketosis ---Spare body proteins

Health benefits of starches and fibers

Health effects of fiber -Fruits, vegetables, and whole grain are high in fibers Soluble fibers - health effects 1.) Decreases risk of heart disease ---Lowers cholesterol by binding to bile and being excreted. ------Reduces blood pressure ------Reduces inflammation 2.) Decreases risk of type 2 diabetes ---Slows glucose absorption by decreasing gastric transit time. 3.) Decreases risk of colorectal cancers: ---Removes cancer causing agents ---activates cancer-killing molecules ---Inhibit inflammation via bacterial fermentation 4.) Aids in weight management ---Increases satiety by decreasing gastric transit time and increases feelings of fullness due to water binding with fiber. Insoluble fibers - health effects 1.) Improves gut function: prevents constipation by ---increasing fecal weight ---Easing passage through the colon ---Decreasing pressure and strain on GI muscles 2.) Decreases risk of colorectal cancers: ---Removes cancer-causing agents 3.) Aids in weight management ---Increases satiety by decreasing gastric transit time & increases feelings of fullness due to increased bulk in GI No DRIs for insoluble/soluble fibers, only for total fibers: RDA for men - 38 g/day, no UL RDA for women - 25 g/day, no UL Habitual intake: men: 17 g/day women: 16 g/day

Health risks of saturated and trans fats

Saturated Fat: -Increase HDL (good) -Increase LDL (bad) -increase TG (bad) Trans Fat: -decreases HDL (bad) -increases LDL (bad) -Increases TG (bad) Cancer: -Dietary saturated fats & fats from fatty or processed meats pose highest risk ---Promotes, but does not initiate cancer ---Colon cancer has strongest association Obesity: -Dietary fat yields highest amount of energy (9 kcals/gram)

Negative feedback loops

Self-regulating systems in which the product of the reaction feeds back to inhibit/reduce the reaction back to homeostasis.

Active transport

Some nutrients (glucose and amino acids) move against a concentration gradient and require energy to pass through the cell membrane.

facilitated diffusion

Some nutrients require a specific carrier to transport them through the cell membrane.

Triglyceride metabolism

"fed state" -store energy for use later on or use it immediately 1.) TGs (from chylomicrons & VLDLs): -Broken down (by lipoprotein Lipase, LPL) ---LPL secreted from adipose & muscle -Release FFAs + glycerol 2.) FFAs enter the tissues -Muscle: FFAs used for energy -Adipose: FFAs get converted back to TGs ---TGs are the storage form of fats "fasted state" -Break down stored energy for usable energy to the body tissues -Supplies 60% of energy (at rest) 1.) Low glucose => low insulin/high glucagon -Activates hormone sensitive lipase -breaks tgs into FFAs + glycerol 2.) FFAs + glycerol enter the circulation: -Used by liver and muscle for energy -Can be converted to ketone bodies -FAs cannot be converted to glucose

Liver

-1st to receive nutrients from GI tract -Largest solid organ in the body (3 lbs) -Prepares absorbed nutrients for use in the body -Filters the blood to detoxify harmful substances -Produces Biles -Storage site for glucose (glycogen) & micronutrients -Regulates the production of proteins -Total of 500+ vital jobs

Chemical Digestion

-Chemical breakdown of food via secretions -Occurs throughout the Gi tract -Secretory organs: salivary glands, stomach, pancreas, liver, and small intestine.

3 types of muscle

-Circular (esophagus - anus_ ---Internal, pushes food forward -Longitudinal muscles (esophagus - anus) ---Exterior, shortens the segment, allows for mixing -Diagonal (oblique) muscle (stomach) ---Additional mixing

Sphincters

-Circular muscle 'valves' -Periodically and automatically opens and closes to allow food to pass -Controls pace of GI tract contents -Sphincters are needed anywhere there is a change in anatomy/physiology/function 1. Upper esophageal sphincter 2. Lower esophageal sphincter 3. Pyloric sphincter 4. Ileocecal 'valve' 5. Anal sphincters (two)

Polysaccharides

-Complex carbs -Formed by many glucose units plus other monosaccharides; connected through carbon bonds -Glycogen: storage (glucose) - animals ---storage form of energy in the body ---glucose units ---Found in: meat to a limited extent, not found in plants ------food is not a significant source -Starch: storage (glucose) - plants ---Storage form of energy in plants ---glucose units ---found in: grains, root crops, tubers, legumes ------grains = richest source ------body hydrolyzes starch to glucose, uses glucose for energy ------global food staple -Fibers: structure (various monosaccharides) - plants -Found in all plant-derived foods ---Provide structure in stems, leaves, roots, skins, and trunks ---Made from a variety of monosaccharides (not just glucose) ---Bonds between monosaccharides cannot be broken by digestive enzymes ------Pass through the body undigested ------Don't contribute energy -Insoluble fibers: benedit GI health -Soluble fibers: benefit heart disease, diabetes, cancer, weight management; more viscous and fermentable ---viscous fibers: form gels in GI tract ---fermentable fibers: digested by GI bacteria -Functional fiber: natural fiber extracted from plants or manufactured, then added to foods or supplements to provide health benefits ---Total fiber in foods = dietary + functional

Moderation

-Consume low-nutrient dense, high- energy dense foods only on occasion

Organic Nutrients

-Contain carbon -Carbs, lipids, proteins, fats, vitamins -Complex structure

Blood stream as transport

-Directly to blood vessels ---Water soluble nutrients ---smaller products of fat digestion

Inorganic nutrients

-Don't contain carbon -*Water and minerals* -Simple structure

Vitamins

-Don't supply any energy to our body -Micronutrients -13 key vitamins regulate our bodies -Organic ---Can be destroyed: heat, light, and chemical agents

Minerals

-Don't supply energy -Micronutrients -16 essential minerals -Inorganic ---invulnerable to light, heat, or chemical agents

Regulation of GI tract (negative feedback loop)

-Gastrin ---Food enters the stomach => cells of stomach wall secrete: gastrin => stimulates the stomach to release: HCL => stomach pH reaches 1.5 acidity => protein digestion occurs => LOOP -Secretin ---When acidic chyme enters the small intestine: cells of small intestine (duodenum) wall secrete: secretin => stimulates the pancreas to release: bicarbonate => duodenum pH becomes less acidic => digestive enzyme activity => LOOP -CCK ---When 'fat-rich' chyme enters the small intestine: cells of small intestine (duodenum) secrete: CCK => stimulates the gallbladder to release: bile => Partially digested fat => LOOP Hydrochloric acid (HCL) - 'activates' enzymes that break down protein Bicarbonate - decreases acid to optimize the environment for the digestive enzymes Cholecystokinin (CCK) - Stimulates the secretion of bile for fat digestion

Diet-planning how to's

-Identify which DGA pattern you prefer -Identify foods within the 5 food groups -Identify which foods are rich in select macro- and micronutrients -Consider foods you ENJOY -Choose a variety of foods from each food group -Make dietary improvements little by little -Be mindful of ultra-processed foods.

Variety

-Increased variety within food groups because not all foods are created equal

Lymphatic vessels as transport

-Lymphatic vessels then to bloodstream ---Larger fats and fat-soluble vitamins -- which are insoluble in water

Lipids

-Major form of stored energy -Stored as adipose tissue (fat) -Used to make cell membranes and other complex molecules

Saliva

-Moistens food for easy passage -Protective role: teeth, mouth, esophagus, stomach -Enzymes initiate carb digestion

Monosacharides

-Most abundant organic molecules in nature -Glucose ---most abundant in nature ---broken down in cells => produces energy ---can be found in disaccharides and polysaccharides -Fructose ---One of the sweetest sugars ---Occurs naturally in fruits, honey, vegetables ---when combined with glucose = sucrose (table sugar) -Galactose ---When combined with glucose = lactose

Stomach (upper digestive tract)

-Movement of bolus: upper to lower portion of stomach, mixes with digestive juices ---Bolus => chyme -Temporarily stores food (~1 liter/~2 lbs)

small intestine

-Nearly all absorption of macronutrients -Travels down three segments: duodenum, jejunum, ileum -~10 ft long with a sa of 2700 sq ft -receives bile (from gallbladder) -Receives digestive juices (from pancreas)

Mechanical Digestion

-Physical breakdown of food using various muscles -Occurs throughout the GI tract, not just in the mouth

Carbohydrates

-Primary source of short-term energy -Used to build other molecules and structures in cells.

Gastric Juices

-Protein digestion (hydrochloric acid) ---heartburn -Mucus protects stomach lining -pH below 2

Enzymes

-Protein facilitator of chemical reactions ---Breaking down, making, or changing molecules -Catalyst: enzymes remain unchanged -Hydrolysis: addition of water to break molecules into small pieces -Organ of origin + compound + ase = enzyme

DRIs & DGAs for Protein

-RDA set to prevent negative nitrogen balance ---AMDR (lower range) set to include RDA -No UL => Protein isn't toxic ---AMDR (Upper Range) => what's "left over" after CHO and FAT DRI: 0.8 g/kg body weight/day DGAs: Consume a variety of protein right foods by mixing and matching: -seafood -lean meats -legumes Limit: -fatty and/or processed meats

Pancreatic Juices

-Released via ducts into duodenum (small intestine) -Enzymes act on all three energy nutrients ---Carbs, fats, proteins -Sodium bicarbonate ---Basic/alkaline ---Neutralizes acid in chyme from stomach -Bile ---Produced in the liver ---Concentrated, stored, and released in the gallbladder ---Squirts into the duodenum ---Emulsifier (NOT an enzyme) ------Disperses fat in watery solutions ------Gives digestive enzymes access to fat molecules

lipid characteristics, digestion, and function

-Triglycerides ---Most abundant ---"3 fatty acids" ------Usually contain different fats ---Glycerol backbone ---formed via condensation reactions -Glycerol -Sterols TRIGLYCERIDES: Fatty Acids (FAs) -Organic acid -Methyl group at one end (CH3); acid group on the other (COOH) -Usually even number of carbons ---18-carbon fatty acids abundant in food ---Long chain (>12 carbons) ---Medium chain (8-12 carbons) ---Short chain (<6 carbons) -Saturations ---Saturated = full of hydrogens ---Unsaturated = missing hydrogens ------Double bonded Cs 2 main types of unsaturated FAs -Monounsaturated FAs ---1 double bonded C ---9 Cs away from CH3 = omega 9: Oleic acid -Polyunsaturated FAs ---2 or more double bonded Cs ---3 Cs away from CH3 = Omega 3: Linolenic Acid ---6 Cs away from CH3 = Omega 6: Linoleic Acid Degree of FA (un)saturation (# of double bonded Cs) -Firmness at room temperature ---Mono & Polyunsaturated fats (most from vegetables) = liquid ---Saturated fats (most from animals) = solid ---Saturated fats (from plants) = solid, but softer than from animals -Stability ---Oxidation -> spoilage of fats ------Polyunsaturated spoil quickly ------Saturated keep the longest Trans-fatty acids -Cis = H next to double bonds on same side of carbon chain. -Trans = H next to double bonds on opposite sides of carbon chain -Body processes trans fat like saturated fat ---Increases blood cholesterol and heart disease risk. PHOSPHOLIPIDS -Phospholipids and sterols ~5% of dietary lipids Phospholipids -Two fatty acids ---Hydrophobic: fat soluble -AND phosphate group + N-containing compound ---phosphate group: hydrophilic: water soluble -Versatile: emulsifiers in food industry -Lecithin: best known phospholipid ---Eggs, liver, soybeans, wheat germ, peanuts -Roles ---Part of cell membranes ---Vitamin and hormone transport in/out of cells ---Emulsifiers: keep fat suspended in blood STEROLS -Multiple-ring structure -Food sources ---Cholesterol: animal sources (meat, eggs, seafood, poultry, dairy) ---Plant sterols: structurally similar to cholesterol: bile acids, sex & adrenal hormones, vitamin D ------90% of body cholesterol = in cells (=/= energy) ------Cholesterol made in the body = endogenous (synthesized by liver) ------ Cholesterol made outside the body (foods) = exogenous ------Accumulation in artery walls and plaque formation = harmful

Main Mastication Muscles (mouth)

-Up/Down => Masseter & Temporalis -Side/side => Pterygoids (under Masseter) -Tightens Cheeks => Buccinator -Moves food in mouth => Tongue

Absorptive System - Small Intestine

-Villi ---Fingerlike projections as intestinal folds - thousands per fold ---(sea anemone) ---Select and regulate nutrients absorbed based on needs of body -Microvilli ---Enzymes and "pumps" act on different nutrients -Crypts ---Glands secrete intestinal juices = digestion -Goblet cells ---Secrete mucus = protection

Scientific Method

1. Develop a question 2. Hypothesis 3. Experiment (Design a study) 4. Results/interpretation 4a. Hypothesis rejected 5a. Develop a new question => Hypothesis 4b. Hypothesis supported 5b. Hypothesis consistently supported 6b. Theory

2020 DGA Key Guidlines

1. Follow a healthy dietary pattern at every stage of life -Healthy U.S., Vegetarian, Mediterranean 2. Customize & enjoy NUTRIENT-DENSE food & beverage choices to reflect personal preferences, cultural traditions, & budgetary considerations -Nutrient Dense: Foods high in nutrients and relatively low in kcals -Energy Dense: Foods low in nutrients and relatively high in kcals 3. Focus on meeting food group neds with nutrient-dense foods and stay within calorie needs -Dairy ---fat free or low-fat milk, yogurt, and cheese ---lactose-free versions ---fortified soy beverages and yogurt alternatives -Vegetables ---All types and colors -Fruits -Grains ---1/2 as whole grain -Proteins ---lean meats, poultry, and eggs ---seafood ---beans, peas, and lentils ---nuts, seeds, and soy products 4. LIMIT foods higher in added sugars, saturated fat, sodium, and limit alcohol consumption. ---Added sugar consumption <10% of calories, ages 2+ ---Saturated fat consumption <10% of calories, ages 2+ --- Either eliminate alcohol consumption or limit to 2 drinks/day for men, 1 drink/day for women

Proteins uses in the body

1.) Growth and Maintenance -Building blocks for most body structures -Allows for movement and function ---Skeletal Muscle = protein ---GI tract = protein ---Heart = protein ---Kidney = protein ---Liver = protein ---Tongue = protein -Major structural component of all cells in the body ---Collagen (protein): Most abundant protein in the body ------Material for ligaments and tendons ------Basis of bone and tooth formation ------Provides the "glue" between cells of artery walls ------Tissue repair -Replacement of dead or damaged cells ---Average life of skin cells are 30 days ---GI tract cells turn over every few days 2.) Enzymes -Break down (catabolic) substances -Build up (anabolic) substances -Transform substances -Enzymes = catalysts ---Facilitate reactions ---They remain intact 3.) Hormones (some) -Insulin, glucagon, ghrelin, CCK, thyroid hormones, growth hormones -messenger molecules -Transported in blood from glands to target tissues -Elicit responses in target tissues to maintain homeostasis 4.) Regulators of fluid balance 5.) Acid-base regulators -Proteins = buffers that maintain acid-base balance in body 6.) Transporters -Carry nutrients and other molecules -Cell membrane "pumps" 7.) Antibodies -Defend body against disease -Body detects antigens (invaders) and makes antibodies (protein molecules that combat specific antigens) 8.) Energy/glucose -Starvation or insufficient CHOs: PRO => Amino Acids => Energy -Priority: Help maintain blood glucose (which may cost lean body tissue)

Consensus on dietary vs circulating cholesterol (and interaction with fiber)

1.) TGs from excess saturated fat = more bile needed, thus increasing liver production of cholesterol 2.) More lipid droplets = more VLDLs & LDL 3.) Too many LDLs can 'overload' the system and cause plaque formation.

Health risks of added sugars

Added sugars: sugars and syrups added to foods and beverages during processing ---Sucrose ---High fructose corn syrup -Sugar Sweetened Beverages (SSBs) ---Moderate evidence that increased SSB consumption is associated with increased adiposity (in children) -DRIs: No RDA, AI or UL or added sugars or total sugars -DGA recommendations for added sugar are based on: ---discretionary calories: whatever's left after all other nutrient needs are met. ---no direct evidence related to health (except dental cavities) -Recommendations: <10% of daily energy intake from added sugars.

AI

Adequate Intake -Average daily amount of a nutrient that appears sufficient to maintain health when an RDA can't be set due to lack of information. -Relies on judgement: less valid

Acceptable Macronutrient Distribution Ranges

Adequate energy and nutrients intake -45-65% of kcals from carbs -20-30% of kcals from fats -10-35% of kcals from proteins

Food first mentality

All nutrient needs can and should be fulfilled with foods and not supplements.

Protein characteristics, digestion, & function

Amino Acids are the building blocks of protein AA Atoms: -Carbon, Hydrogen, Oxygen, Nitrogen Two types of Amino Acids: 1.) Essential amino acids -body needs but cannot make -essential to get these from food 2.) Nonessential amino acid -body needs but can synthesize -not needed in the diet Peptide bonds connect amino acids to form proteins -2 AAs bonded: dipeptide -3 AAs bonded: tripeptide -4+ AAs bonded: polypeptide Most proteins contain 10s-100s of AAs

Reactions: catabolic vs anabolic

Anabolic: -Build up of body compounds -Requires energy Catabolic -Break down of body compounds -Releases energy

Estimated Energy Requirement

BMR+TEF+PA=EER = energy required for weight stability = energy intake -Use formulas below: -PA needs estimated from PA factor ---PA factor - Men - Women - Physical activity ---Sedentary - 1.0 - 1.0 - Typical daily living activities ---Low Active - 1.11 - 1.12 - +30-60 min moderate activity ---Active - 1.25 - 1.27 - +>60 min moderate activity ---Very Active - 1.48 - 1.45 - +60 min moderate activity +60 min vigorous activity or + 230 min moderate activity Men: (662-(9.53 x age)) + PA x ((15.91 x weight in kg)+ (539.6 x height in m)) = kcal/d Women: (354-(6.91 x age)) + PA x ((9.36 x weight in kg)+ (726 x height in m)) = kcal/d

Expenditure:

Basal Metabolic Rate (BMR) -Minimum energy required to fuel basic life processes like: ---breathing, making red blood cells, heart beating, etc -Men - 1400-2230 kcal/day -Women - 1240-1570 kcals/day -Factors that influence: ---down with aging ---increase with growth --- increase with lean mass (muscle) ---increase when a fever (infection) or stress are present ---Decreases with malnutrition ---Increases when the body has to filter out chemicals -Estimating your BMR ---Weight in kg = weight in lbs/2.2 ---Height in cm = height in in*2.54 ---Men: (10 x eight in kg) + (6.25 x height in cm) - (5 x age) + 5 =BMR ---Women: (10 x eight in kg) + (6.25 x height in cm) - (5 x age) - 161 =BMR Thermic Effect of Food (TEF) -Energy used in digestion and absorption ---GI tract functioning accelerates in response to eating ---Varies by macro, meal size & meal frequency ------Greater for high-protein foods than for high-fat or high-carb foods ------Greater for meals eaten quickly than over a few hours ---Not very reliable Physical Activity (PA) -Voluntary movement of skeletal muscles ---Most variable component of energy expenditure ------Purposeful PA = exercise ------Non-purposeful PA = moving -Amount of energy needed for PA depends on: ---Muscle mass & total body weight ---Activity: duration, frequency, and intensity

Carb Digestion

Break ingested foods into smaller molecules for use by the body Mouth -Small amount of digestion (~5%) ---Salivary Amylase Stomach -NONE -Stomach acid neutralizes salivary amylase Small Intestine -Most digestion occurs here (~95%) ---Pancreatic Amylase (from pancreas) ---Glucose requires active transport ---Fructose gets simple diffusion Large intestine -None, but fermentation occurs

BMI

Calculating BMI Relative weight for height -BMI = weight (kg)/height (m)^2) or -BMI = (weight (lb)/height (in)^2) * 703 BMI and Health Risks -Good screening tool for disease risk -Not a measure of body composition -Problematic for muscular bodies BMI - Health status in the US -2% underweight (<18.5) -25% Healthy weight (18.5-14.9) -31% overweight (25-29.9) -33% Obesity (30-39.9) -9% extreme obesity (40+)

Lipid transport in blood

Chylomicrons: -Lipoprotein: transport vehicle for lipids ---Chylomicrons are the largest lipoproteins -Transports lots of TGs to most peripheral tissues ---Adipose tissue ---Muscle ---Liver -As the TGs get dumped off, they get smaller -The smaller versions then go to the liver and are repackaged into very low density lipoproteins (VLDL) Very Low Density Lipoproteins (VLDL) -Made in the liver -Full of TGs (but have < than Chylomicrons) -Transports lots of TGs to most peripheral tissues ---Adipose tissue ---Muscle ---Liver -As the TGs get dumped off, they get smaller -Become Low Density Lipoproteins (LDL) Low Density Lipoproteins (LDL): -Lipoproteins made from VLDL -<TGs than VLDL and Chylomicrons -Contains mostly cholesterol -Transports cholesterol to cells to ---Make hormones ---Used for bile ---Build new Cell Membrane -Liver removes some from blood -too much = a lot of problems High Density Lipoproteins (HDL) -Not made from LDL -Made by the liver -Removes cholesterol from cells ---Carries it to liver and gets recycles/disposed -Too little = not protective

Peristalsis

Circular & longitudinal muscles working together --- Moves chyme forward; Rate and intensity of contractions vary on GI segment ---Factors that may interfere with peristalsis: stress, drugs, illness

Segmentation

Circular muscles in stomach and small intestines that contract and relax ---Churns chyme to mix with digestive juices ---Promotes contract with absorbing cells

Esophagus (upper digestive tract)

Connects the mouth to the stomach ~ 1 foot long

Vitamin & mineral deficiencies when limiting animal source foods

Deficiencies in Iron, calcium, vitamin D, vitamin B-12, and protein are very common, however, are preventable with the right foods.

Dietary Guidelines for Americans

Developed by nutrition scientists/physicians -Food-based recommendations for healthy individuals to help: ---meet nutrition needs ---promote health ---reduce risk of disease

Role of enzymes and coenzymes

Enzymes: -Facilitate metabolic reactions -Protein catalysts (do not change, themselves) Coenzymes: -Organic molecules; NOT proteins -Associate with specific enzymes ("little helpers") -Without coenzyme, an enzyme cannot function

EAR

Estimated Average Requirement -Average daily amount of a nutrient REQUIRED to maintain health. -50% of adults

EER

Estimated Energy Requirement -Average intake required to maintain energy balance ---Energy balance= Energy in = Energy out -Applies to weight and physical activity -No UL, but adverse health effects for consistent high calorie intake.

Metabolic processes during fasted/fed state

FED Fat -Fat yields the most energy per gram ---Fatty acid bonds = mostly between C and H ------Oxygen added to form CO2 and H2O => ------H+ released to electron transport chain=> ------Energy is captured in bonds of ATP => ------Oxidized 16 carbon fatty acid molecule = 129 ATP (vs glucose ~ 30 ATP) ------More ATP=more energy Protein -Excess protein ---Body can't store excess amino acids (must be changed) ---First: normal daily losses are replaced ---Second: oxidation increases (produces energy) ---Third: amino acids deanimated, remaining carbon => ketone bodies (stored as fat in adipose tissue) -Excess Carbs: ---First: storage as glycogen (limited space) ---Second: oxidation increases (produces energy; prevents dietary and body fat from oxidation) ---Third: converted and stored as fat FASTING Carbs, fat, and protein -In the beginning ---Glucose (from liver's glycogen stores) and fatty acids (from adipose tissue's stored fat) = released to travel to cells ------Broken down to acetyl CoA (provide energy -Next ---Liver glycogen is depleted, blood glucose levels fall ---Cells begin to degrade their components to provide fuel ---Fat breakdown => fatty acids (used by most cells) Glucose -Needed by nervous system and red blood cells ---Gluconeogenesis: some amino acids => pyruvate => glucose ---Glycerol portion of triglyceride => glucose ---Breakdown of body proteins (lean muscle, liver) => glucose ------"Expensive" way to obtain glucose ------First few days: body protein provides 90% of needed glucose (glycerol = 10%) Shift to Ketosis -Use fat to obtain fuel brain ---Acetyl CoA fragments (from fatty acids) => Ketone bodies ---Slows the rate of body protein breakdown (but many areas of brain need glucose) Ketosis Chemistry: -Ketone body + Acid group (COOH) = keto acid -High concentration = blood pH drops (becomes more acidic) Ketosis Result: -Fasting hormones slow metabolism -Loss of appetite -Reduces energy output -Conserves lean tissue and fat (weight loss =/= fat loss) Symptoms of starvation -Physical: wasting; slowed heart rate, respiration, metabolism; lowered body temperature; impaired vision; organ failure; reduced immunity -Psychological: depression; anxiety; food-related dreams/obsessions

Glucose & hormone interactions

FED STATE: Blood glucose rises (during/after meals): triggers release of insulin (moves glucose to cells to store excess) → blood glucose level is lowered FASTING STATE: Blood glucose falls (between meals, overnight): triggers release of glucagon (moves glucose out of storage t0 fuel body) → blood glucose level is raised Diabetes: High blood glucose levels -Insulin is either ineffective or inadequate -Type 1: Pancreas doesn't produce insulin -Type 2: Cells don't respond to insulin and pancreas eventually stops producing. Hypoglycemia: low blood glucose -Less common; usually a result of poorly managed diabetes.

Intake: Hunger, satiety, and satiation vs food cravings and reward

Hunger: -Physical sensations reflecting the urge to eat -Characteristics: light-headedness, weakness/jittery, stomach emptiness/growling, and/or agitation. -Determines when to eat & impacts how much to eat Satiation -Physical sensations reflecting the urge to stop eating -Characteristics: stomach expansion/fullness -Reduced hunger and increased fullness as a result of eating/drinking (positive energy balance) Satiety -Physical sensations reflecting the urge to not eat (again) -Characteristics: stomach expansion/fullness -Reduced hunger and increased fullness as a result of previously eating/drinking (positive energy balance) Cravings -Physical sensations reflecting the urge to eat -Characteristics: Thinking about/craving specific foods -Cravings originate in the 'cortico-limbic' brain regions associated with reward

Protein & health

Protein Excess -Increased dietary protein increases ammonia and urea production ---Increased liver and kidney function Health risks -Cardiometabolic risks ---No Causal role of increased protein and CVD risk ---No Causal role of increased protein and Type 2 diabetes risk ---Many protein-rich foods are protective against CVD -Cancer Risks ---No causal role of increased protein & cancer *Processed & fatty meat consumption is associated with CVD and Cancer risks

Metabolic compounds: Pyruvate, acetyl CoA, Oxaloacetate

Pyruvate: - 3-carbon structure -Glucose, amino acids, and glycerol => pyruvate -Can be used to make glucose Acetyl CoA -2-carbon structure -Fatty Acids => acetyl CoA -Cannot be used to make glucose -Enters TCA cycle -Energy harnessed through electron transport chain

Pyruvate's options: lactate cs Acetyl CoA

Quick energy needs: anaerobic -Not requiring oxygen -Pyruvate => lactate -Energy =/= sustainable -At rest: occurs to a limited extent -During high intensity exercise: ---Increase in pyruvate (produces ATP quickly) ---Excess of H-carying coenzymes (overwhelms mitochondria in the cells) and electron transport chain can't accept H -Pyruvate accepts hydrogens ---(Also due to a lack of oxygen in cells) ---Converts pyruvate to lactate ---Coenzymes are released to pick up more H to continue glycolysis -Accumulation of lactate in muscles coincides with: ---Drop in pH, burning pain, fatigue -Cori cycle returns lactate to glucose in the liver Slower energy needs: aerobic -Requiring oxygen -Pyruvate => acetyl CoA -Greater energy yield, more sustainable ---Oxygen and mitochondria are available ---H+ can be carried by coenzymes to electron transport chain -Pyruvate enters mitochondria of cell ---Carbon group removed (becomes CO2) ---2-carbon compound joins with CoA; becomes acetyl CoA -Irreversible

DRIs and DGAs for carbs

RDA set to meet the brain's needs (only) -AMDR set to include the whole body's requirements -RDA =/= AMDR No UL -but AMDR set to reduce excess cho, therefore reducing risk of obesity CHO RDIs for adults -RDA: 130 g/day -AMDR: 45-65% Habitual intake -250 g/day -AMDR: 50%

RDA

Recommended Dietary Allowance -Average daily amount of a nutrient RECOMMENDED to meet the needs of most people in good health. -98% would not be deficient if they met this requirement.

Study Design

Relationship (Association) => Observational Study Cause & Effect => Experimental Study (Intervention Trial)

Anus

Releases stool

large intestine

The last section of the digestive system, where water is absorbed from food and the remaining material is eliminated from the body -Segments: ascending => transverse => descending => sigmoid

Mortality Risks with animal source foods

There is no causal relationship between consumption of animal proteins and increased health risks. All studies are observational and fail to eliminate external factors.

UL

Tolerable Upper Intake Level -Maximum daily amount of a nutrient that appears to be healthy for most adults. -Exceeding can lead to toxicity and other negative health impacts.

Protein Deficiency

Too little total protein, missing essential AAs Significant impact on children and adults: -Reduced growth ---Muscle ---Bone -Reduced physical function ---Weakness ---fatigue Most common sign of protein malnutrition is stunted growth

Fat Digestion

Ultimate goal: Break ingested food into smaller molecules for use by the body Mouth -Small amount of digestion (<5%) ---Lingual (tongue) lipase Stomach -Small amount of digestion (5-25%) ---Lingual Lipase (from mouth) ---Gastric lipase (from stomach) Small intestine -Most digestion occurs here (~75%) -Emulsifying fats 1.) Fat stimulates CCK secretion (from small intestine) 2.) CCK stimulates Bile secretion (from gallbladder) -Bile: ---Made from cholesterol ---Made in the liver ---Stored in the gallbladder ---Acts as a emulsifier 3.) Bile stimulates the breakdown of large fat globules into smaller droplets Large Intestine -None -Can carry some important fat-related components out of the body ---Bile sales (contain cholesterol) ---Cholesterol (prior to micelle formation)

Body fat distribution

Visceral fat Some risk in small quantities, high risk in large quantities -Stored in/around abdominal organs -Contributes to heart disease, cancers, diabetes, & related deaths Subcutaneous fat Protective in small quantities, no risk in large quantities -Stored under skin -No disease associations -Contributes to fuel/metabolism, protection insulation

Optimal Intakes

Weight in kg * 1.2 = bottom limit per day weight in kg * 1.6 = top limit per day

Diffusion

When some nutrients simply cross through the cell membrane into intestinal cells freely