Nutrition Exam 2
fat and disease
-heart disease -cancer -obesity do we need to know more?
Roles of Protein
1. As Structural Materials - Building blocks for most body structures -Collagen matrix -Replacement of dead or damaged cells 2. As Enzymes -Break down, build up, and transform substances -Catalysts 3. Hormones -Messenger molecules -Blood carries to target tissues -Insulin and glucagon are protein hormones 4. Regulators of fluid balance -Edema 5. Acid-base regulators -Attract hydrogen ions and act as buffers 6. Transporters -specificity -sodium and potassium active transport 7. Antibodies -Defend body against disease (Antigen and antibody) -Specificity (immunity—memory) 8. Source of energy and glucose -Starvation and insufficient carbohydrate intake 9. Other roles -Blood clotting, vision
linoleic acid
18 carbon, omega-6 fatty acid. double bond at the 6th carbon
linolenic acid
18-carbon, omega-3 fatty acid
Sugar
Added sugars are linked in diabetes, inflammation, hypertension, and heart disease. The more added sugars in the diet, the more difficult it is to meet recommendations for protein, dietary fiber, vitamins, and minerals while staying within kcalorie limits. The fruit's sugars arrive in the body •diluted in a large volume of water •packaged in fiber •mixed with essential vitamins, minerals and phytochemicals Added sugars contribute nutrient deficiencies by displacing nutrients. Sugar is not "bad" nor should it be entirely avoided, but nutritious foods must take priority in daily eating. If nutritious foods crowd sugar out of the diet, that's fine - but not the other way around. Recommendations urge consumers to limit daily intake of added sugars to 10% of total kcalories. For most people, this is a reduction.
Excess glucose as fat
After meeting its immediate energy needs and filling its glycogen stores to capacity, the body must find a way to handle any extra glucose. When glucose is abundant and glycogen stores are full: > the liver uses more glucose instead of fat for energy > the liver converts extra glucose to fat. Fat stores are unlimited.
Using Amino Acids to Make Glycogen and Fat
Amino acids are not stored in the body like triglycerides from fats and glucose from carbohydrates. When energy intake exceeds the body's needs, excess protein is converted to -Glucose via gluconeogenesis (stored as glycogen) -Ketone bodies via deamination (stored as fat)
Using Amino Acids to Make Other Compounds
Amino acids can be used to make compounds other than proteins called neurotransmitters Norepinephrine and epinephrine:messengers of the nervous system Melanin: a pigment responsible for hair, eye, and skin color Serotonin: a neurotransmitter involved in sleep regulation, appetite control, and sensory perception
Converting Ammonia to Urea
Ammonia is a toxic compound and must be cleared from the body. The liver does this by combining ammonia with carbon dioxide, producing urea. Urea products increases as dietary protein increases.
Alternative Sweeteners
Artificial sweeteners are non-nutritive sweeteners •Adverse effects with large doses •It is undetermined as to whether their ingestion is safe for human beings in quantities people normally use Stevia—herbal product •Generally recognized as safe (GRAS) •Acceptable Daily Intake (ADI) is 9 packets Sugar alcohols (polyols) •Provide kcalories •Do not contribute to dental caries
Dental Cavities
Bacteria ferment sugars producing acid •Erodes tooth enamel Food factors associated with tooth decay •Time of food in mouth •Sticky foods •Frequency of sugar consumption
protein chemistry
Carbon, hydrogen, oxygen, plus nitrogen Amino acids -Carbon (C) -Hydrogen (H) -Amino group (NH2) -Acid group (COOH) -Side group or side chain The side group is a unique chemical structure that differentiates one amino acid from another.
Polysaccharides
Chains of monosaccharides Complex. Glycogen, starch, fibers Polysaccharides are "complex" because they have hundreds of glucose molecules chained together, sometimes with other monosaccharides. glycogen: storage form of energy in animals starch: storage form of energy in plants. 1. If highly branched, starch is called amylopectin 2. If unbranched, starch is called amylose fiber: the structural material in plants. Differs from starches in that its bond make fiber indigestible. 1.Soluble Fibers 2.Insoluble Fibers 3.Functional Fibers
liver
Conversion of fructose and galactose
Eiconsanoids
Derivatives of 20-carbon fatty acids and biologically active compounds -"Hormonelike" in that they have body functions such as regulating blood pressure and clotting -Health benefits: - Omega-3 eicosanoids help lower blood pressure and prevent blood clot formation, protect against irregular heartbeats, and reduce inflammation - Omega-6's protect heart health by lowering LDL cholesterol and improving insulin resistance
Diabetes
Diabetes •Insulin either inadequate or ineffective •Type 1: pancreas fails to produce insulin. •Type 2 diabetes: cells fail to respond to insulin. This condition tends to occur as a consequence of obesity.
Protein Quality
Digestibility: is the measure of the amount of amino acids absorbed from a given protein .Amino Acid Composition: is considered when assessing protein quality to determine the degree to which a protein provides the 9 essential amino acids. Reference Protein is a standard against which to measure the quality of other proteins. High-Quality Proteins contain all the essential amino acids in relatively the same amounts that humans require (they may also contain nonessential amino acids). Complementary proteins are two or more proteins whose amino acids assortments complement each other in such a way that the essential amino acids missing from one are supplied by the other. When an essential amino acid isn't supplied in the amount needed to support protein synthesis, it is called a limiting amino acid.
protein absorption
During absorption, amino acids are transported by specific carriers to intestinal cells. Once absorbed into the intestinal cell, amino acids can be used for energy or to create compounds. Amino acids unused by these cells are transported to the liver. Whole proteins are handled better than "predigested" amino acids, because the body dismantles and absorbs them at an optimal rate for the body.
active transport
Energy-requiring process that moves material across a cell membrane against a concentration difference Glucose and Galactose
Cholesterol
Exogenous cholesterol is cholesterol originating from outside the body (from foods). Endogenous cholesterol is cholesterol made in the body. •The liver makes body cholesterol from fragments of carbohydrate, protein, and fat •Contributes more cholesterol to the body than does the diet (800-1500mg compared to the Daily Value from food of 300mg per day) •Body cholesterol serves as the starting material for critical compounds such as bile acids, hormones (testosterone and estrogen), and Vitamin D. •Body cholesterol is also necessary for building the structures of cell membranes (more than 90% of all body cholesterol is found in cells) Cholesterol can be harmful when it accumulates in the artery walls, forming plaque, whereby it leads to atherosclerosis.
lipid digestion
Fats are hydrophobic and digestive enzymes are hydrophilic Goal of fat digestion- Dismantle triglycerides- Monoglycerides, fatty acids, and glycerol mouth: fat digestion starts with lipase stomach: grinds solid fat pieces into finer particles, mixes the chime with gastric secretions like gastric lipase, and disperses fat into small droplets. small intestine: fat triggers CCK. CCK signals gallbladder to release bile which emulsifies and mixes with fat molecules and fluids for hydrolysis. pancreatic lipases remove fatty acids from glyercol large intestine: some remaining bile is trapped by dietary fibers and excreted.
rancidity in fats
Fats spoil (go rancid) when exposed to oxygen. Heat and light exposure speed up rancidity. •Polyunsaturated fats spoil most readily because their double bonds are unstable •Monounsaturated fats are slightly less susceptible •Saturated fats are resistant to oxidation and lease likely to go rancid
Glucose into energy
Glucose is the preferred source of energy in brain and nerve cells. After a meal, blood glucose rises. Liver cells link excess glucose molecules (by condensation) into long, branching chains of glycogen When blood glucose falls, the liver cells break down glycogen (by hydrolysis) into single molecules of glucose and release them into the bloodstream.
Lipid Absorption and Transport
Glycerol, short and medium-chain fatty acids are absorbed directly into the bloodstream. All three of these are small enough to easily cross into intestinal cells and then into the circulatory system. Larger molecules - monoglycerides and long-chain fatty acids - are transported into the intestinal cells via micelles. They are reassembled into triglycerides, packaged with proteins and circulate through the lymphatic system
Sterols
Have a multiple-ring structure that differs from other lipids. Roles of sterols - Made in the body - Structural component of cell membranes Food sources include: - Animal sources: Cholesterol, Vitamin D, bile, and some hormones - Plant sterols
lactase activity
Highest immediately after birth Declines with age Symptoms of intolerance include bloating, diarrhea. Lactase deficiency may develop when intestinal villi are damaged due to disease, medicines, prolonged diarrhea, or malnutrition. Prevalence varies widely and has a genetic component: lowest among northern Europeans and highest among Asians
Atoms and Bonds
Hydrogen- one bond Oxygen- two bonds Nitrogen- three bonds Carbon- four bonds
Carbohydrates
Include sugars, starches, and fiber. They are found in grains, legumes, fruit, vegetables, and milk. They supply cells with glucose for energy.
Dietary changes with lactose intolerance
Manage dairy intake rather than restrict intake - GI bacteria - Fermented milk products (Benefits to lactose digestion) Individualized diets -Presence of lactose in non-dairy products Potential nutrient deficiencies -Potassium, vitamin D, and calcium
Enterohepatic Circulation
Most of the bile released into the small intestine is reabsorbed and sent back to the liver to be reused.
Protein Digestion Steps
Mouth: crushes protein Stomach: hydrochloric acid uncoils (denatures) protein strands via hydrolysis. Hydrochloric acid activates pepsin, an enzyme that cleaves proteins into small polypeptides and amino acids. Small intestine: enzymes called proteases hydrolyze proteins further into short peptide chains, tripeptides, dipeptides, and amino acids. Peptidase enzymes on intestinal cells split most di-and tripeptides into single amino acids.
Disacchardies
Pairs of monosaccharides Simple sugar. maltose, sucrose, lactose
Amino Acid Structure
Primary structure—chemical bonds bind two amino acids together to form a dipeptide, then a tripeptide, then as additional amino acids join the chain, a polypeptide Secondary structure—electrical attractions within the polypeptide chain twist into a shape that gives proteins strength and rigidity Tertiary structure—hydrophilic and hydrophobic side groups of each amino acid in the polypeptide chain react to water molecules, twisting into a ball shape Quaternary structure—two or more polypeptides
Facillitated diffusion
Process that moves materials from high to low concentration with the help of protein channels; does not require energy Glucose and galactose Carbohydrate-rich meal Fructose-specific transporter
Using Amino Acids for Energy
Protein contributes ~10-15% of the body's daily energy needs (the rest is met by carbohydrate and fat). Protein as an energy source may increase if energy from carbs and fats is restricted. If necessary, the body will break down proteins from lean muscle tissue and use amino acids to meet energy needs. Over time, energy deprivation leads to wasting of lean body tissue.
Health Effects of Protein
Protein deficiency -Body protein synthesis decrease and degradation occurs, creating protein-energy malnutrition -Consequences include slowed growth, impaired brain and kidney functions, poor immunity, and inadequate nutrient absorption -Largely a concern in developing countries, where severe malnutrition occurs including marasmus and kwashiorkor Heart disease -In the US, protein intake is so abundant that excess consumption is our primary concern »Correlation between animal-protein intake and heart disease »Note: animal-protein also contains high amounts of saturated fat Cancer -Protein does not seem to increase risk of cancer, but some foods that contain high amounts of protein do -Processed meat and red meat (named carcinogens by World Health Organization) -Soy, legumes, fish, and milk lower cancer risk Adult bone loss (osteoporosis) -High protein intake can accompany an increase in calcium excretion -Bones need both protein and calcium for optimal growth Weight control -High-protein, low-carbohydrate diets may be effective due to overall kcalorie decrease and protein-induced satiety Kidney disease -In people with kidney disease, high protein intake can accelerate kidney deterioration
Nitrogen Balance
Protein synthesis is balanced with protein breakdown. Protein intake from food is balanced with nitrogen excretion (urine, feces, sweat). Zero nitrogen balance: nitrogen intake equals output Positive nitrogen balance: the body synthesizes more protein than it degrades (protein is added)»Examples: infants, pregnancy, adolescence, illness recovery Negative nitrogen balance: the body degrades more protein than it synthesizes (protein is lost). »Examples: starvation, severe body stress i.e. burns or fever
protein metabolism
Proteins are continually being broken down into amino acids and being made from amino acids within each cell. These amino acids mix with dietary amino acids to form an "amino acid pool" within the cells and circulating blood. The rate of protein turnover may change, but the pattern of amino acids remains fairly constant within the pool. These amino acids can be used to make proteins or can be stripped of their nitrogen and used for glucose or energy.
Amino Acids
Proteins are made up of about 20 common amino acids. - "Nonessential" amino acids are made in the body. - "Essential" amino acids are those the body cannot make in significant quantities to meet needs. - "Conditionally essential" amino acids are those that are usually nonessential but, under certain conditions, must be supplied by the diet.
Glucose from Protein (ketones)
Proteins have their own jobs to perform that cannot be done by other nutrients. Ketones are an alternative fuel source during starvation. Ketosis disturbs normal acid-base balance. 1.Amino acids of proteins may be converted to glucose via gluconeogenesis. 2.Ketones are made from fat fragments when there is an inadequate supply of carbohydrates. 3.Carbohydrate needs to prevent ketosis are 50-100grams per day.
Protein Digestion
Proteins in foods do not become body proteins directly. Instead, dietary proteins supply the amino acids from which the body makes its own proteins. Enzymes break down the long polypeptides into short polypeptides, then into tripeptides and dipeptides, and finally into individual amino acids that are set to the liver's metabolite pool.
role of triglycerides
Provide the cells with energy Adipose tissue stores body fat - Adipose cells have virtually unlimited ability to store fat energy - Secretes hormones (adipokines) Other uses of fat in the body - Skin insulation - Shock absorption - Cell membrane material - Cell signaling pathways
cis & trans
Refers to the configuration of hydrogens around the double bond. •Trans-fatty acids have hydrogens on opposite sides of the double bond •Cis-fatty acids have both hydrogens on the same side of the double bond (hint: remember cis- and "same")
Fat quality
Replacing saturated fats with unsaturated fats helps reduce risk of heart disease. Regular consumption of omega-3 fatty acids suppresses inflammation, which may protect against some cancers Fish oil supplements are available but not recommended for routine supplementation due to side effects.
Energy nutrients over time
Since the 1970s •Total daily energy intakes have increased •Activity levels have declined •Increase in body weight
Monosaccharides
Single sugar molecules. Simple sugar. glucose, fructose, galactose Have the same numbers and kinds of atoms, but differences in chemical structures create differences in sweetness glucose: blood sugar •Essential energy source •Part of every disaccharide galactose: only in a few foods fructose: fruit sugar
blood glucose
Steady supply in blood stream •Intestines—food •Liver—glycogen Blood glucose homeostasis -Insulin (Moves glucose from blood into cells) -Glucagon and epinephrine (Breaks down glycogen to glucose)
Health Effects
The Current US diet contains excessive solid fats (desserts, pizza, cheese, processed and fatty meats, hot dogs, bacon, and ribs) Focus on quality and quantity -Fats have higher energy (9 kcal) per gram than protein and carbohydrates -High amounts of kcalories from fat-as is the same with carbohydrates and proteins- increase weight -Solid fats provide abundant saturated fat and trans fat
Protein recommendations
The body continuously breaks down and loses some protein. It cannot store proteins or amino acids.To replace protein, the body must get essential amino acids from the diet. 10-35% kcals from protein 0.8 g protein per kg of healthy body weight per day »Increases during life stages of high growth, including infants, children, adolescents, pregnant and lactating women Moderate amounts at each meal best supports protein synthesis and muscle health 10% from nuts, seeds, and legumes 20% from seafood 70% from meat, poultry, and eggs People in the US typically get more protein than they need.
Peptide bonds
The bonds connecting amino acids together to form polypeptide chains through condensation
Using Amino Acids to Make Glucose
The brain, red blood cells, and the nervous system prefer and depend on glucose for fuel. When dietary carbohydrate cannot supply enough glucose, the body can make glucose from amino acids. The body will use protein in the diet or break down lean muscle tissue for amino acids, which are then converted to glucose.
Balance
The maintenance of normal blood glucose depends on foods and hormones. When blood glucose falls below normal, food can replenish it. In the absence of food, glucagon signals the liver to break down glycogen stores into glucose. When blood glucose rises above normal, insulin can signal the cells to take in glucose for energy
Carb Digestion
The ultimate goal of carbohydrate digestion is the absorption of glucose. Mouth: The salivary enzyme amylase works to begin starch digestion Stomach: The activity of amylase diminishes in the stomach due to stomach acid. If fiber is present in the stomach, it delays gastric emptying. The delay in gastric emptying increases one's feeling of fullness and satiety. Small intestine: The majority of carbohydrate digestion and absorption occurs in the small intestine. Maltase, sucrose, lactase, and pancreatic amylase are present. Large intestine: In the large intestine, fiber attracts water. FODMAP digestion produces gas and other symptoms. Fiber is fermented.
Using Amino Acids to Make Proteins and Nonessential Amino Acids
Through transamination reactions in the liver, the body can assemble amino acids into proteins: -Lean tissue can be broken down to make an essential amino acid if one is missing -Cells can turn a keto acid and nitrogen into a nonessential amino acid if one is unavailable -Cells can transfer an amino group from one amino acid to its corresponding keto acid to make a nonessential amino acid
Fat Quanity
US diets provide - 33% of total daily energy from fat and - 11% of total energy from saturated fat Recommended Intakes of Saturated Fat, Trans Fat, and Cholesterol (DRI and Dietary Guidelines): - 20 to 35 percent of daily energy from fat - Less than 10 percent from saturated fat - As little trans fat as possible - No longer limit to <300 mg cholesterol Avoid getting too little fat Recommendation: one teaspoon of fat at meals
Phospolipids
Unique chemical structure that allows them to be soluble in both water and fat. -Emulsifiers in food industry (example: Lecithin) -In the body, part of the cell membranes -Food sources include eggs, liver, soybeans, wheat germ, and peanuts
Excreting Urea
Urea is the body's vehicle for getting rid of unused nitrogen. It is excreted through the urine, which requires water. Therefore, high protein diets (>100g) require high amounts of water to dilute and excrete urea. -High protein diets can cause risk of dehydration -Resulting water loss should not be misconstrued for body fat loss
Vegetarian protein
Vegetarians can receive all the amino acids they need over the course of a day by eating a variety or whole grains, legumes, seeds, nuts, and vegetables -In general, plants are lower quality than animal proteins -Plants offer less protein per weight -Combining plant-protein foods can provide high protein quality
Factors that Lower LDL and/or Raise HDL
Weight control Monounsaturated or polyunsaturated, instead of saturated, fat in the diet Soluble dietary fibers Phytochemicals Physical activity
Deaminiation
When amino acids are broken down, they are stripped of their nitrogen-containing part (NH2): Deamination is the removal of the amino group Results in 2 products: »Ammonia: NH3 »Keto acid: a carbon structure without its amino group Keto acids can be used to make nonessential amino acids, glucose, ketone bodies, cholesterol, or fat.
lipid metabolism
When meals deliver more energy than the body needs, the excess is stored as fat in the adipose cells for later use. After meals, the blood delivers chylomicrons and VLDL loaded with triglycerides to the body cells. Lipoprotein lipase hydrolyzes those triglycerides, releasing fatty acids, diglycerides, and monoglycerides into the cells for energy. Fat supplies 60% of the body's ongoing energy needs during rest. Fat provides energy during food deprivation by dismantling adipose cells into triglycerides and releasing glycerol and fatty acids into bloodstream. During fasting, the body will rapidly metabolize fat for glycerol, which contains a tiny amount of glucose (fatty acids cannot be converted to glucose) However, because the brain, nerves, and red blood cells need glucose, the body will break down its protein cells to produce glucose
Hypoglycemia
abnormally low level of sugar in the blood Prevalence in healthy people is rare. Most commonly a consequence of poorly managed diabetes
HDL (High Density Lipoprotein)
are half protein, accounting for their high density. HDL carries cholesterol back to the liver for recycling or excretion.
LDL (low density lipoprotein)
are higher in cholesterol and lower in triglycerides. They are taken up by cells after binding to receptors. High levels of this lipoprotein have negative health implications.
VLDL (very low density lipoprotein)
are made in the liver. They are circulated to the body in the bloodstream. As cells take up triglycerides, VLDL shrink down in size as only their remnant particles remain.
Partial hydrogenation
chemical process in which hydrogens are added to unsaturated fatty acids to reduce the number of double bonds. •Fats become more saturated (solid) and resistant to oxidation •Most often occurs during food processing, where double bonds remain but are changed from cis- to trans- configuration.
lactose intolerance
condition that results from the inability to digest the milk sugar lactose.
Chylomicrons
contain so little protein and so much triglyceride that they are the lowest in density.
Condensation
create a new water molecule that links two monosaccharides together.is the reaction for storing glucose as glycogen •Liver stores one-fourth of glycogen in the body, releasing glucose as needed. Liver can store only enough glycogen for a day's worth of energy •Muscles store three-fourths of glycogen, but they use glycogen for themselves during exercise •Brain stores a small amount of glycogen as an emergency reserve during severe glucose deprivation
Total hydrogenation
creates saturated fats from unsaturated ones.
Fatty acids
even # of carbons (4 to 24 but 18 is most common)
essential fatty acids
fats needed by the body that must be consumed in the diet because the human body cannot manufacture them -Omega-6 Linoleic acid (vegetable oils and meats) -Omega-3Linolenic acid (fish, flaxseed oil, walnuts) -Can be used to make other fatty acids- DHA - EPA
triglyerides
glycerol + 3 fatty acids. fats & oils. saturated and unsaturated (mono & poly)
lactase deficiency
lack of the enzyme required to digest lactose into its component monosaccharides.
Denaturation
loss of normal shape of a protein due to heat or other factor. ex: curdling of milk Mouth: heat Stomach: hydrochloric acid and pepsin Small Intestine: hydrolysis reactions and peptidase enzymes
Proteins
macronutrients composed of carbon, hydrogen, oxygen, and nitrogen atoms, arranged into amino acids linked in a chain. Some amino acids can be made by the body; others must be obtained through food. Proteins are found in vegetables, legumes, grains, nuts, seeds, dairy, meats, eggs, and fish.
gene expression
overall process of making a protein. Your genes - DNA - contain the code for the amino acid sequences of each protein. The amino acid sequence determines shape or structure, and this shape determines the function. When a cell makes a protein, the gene for that protein is said to be "expressed." Nearly all body cells make human proteins, but each type of cell only makes the proteins it needs. The diet must supply the variety and amount of amino acids required for protein synthesis and gene expression.
saturated vs unsaturated
saturated: solid. no double double, all carbons are linked to hydrogen only unsaturated: liquid. mono: has one double bond and poly: has more than one double bond carbons are fully "saturated" with hydrogen --> no double bonds the methyl (omega) is where you start counting to locate the double bond not every carbon is "saturated" with hydrogens so it must form a double bond --> makes it "unsaturated"
18 carbon fatty acids
stearic, oleic, linoleic, linolenic
Glucose
the brain uses glucose as its primary energy source
Glycogen
the liver and muscles store simple sugars in the form of glycogen Glycogen and glucose provide the muscles and tissue with about half the energy they need.
lipids
triglycerides, phospholipids, and sterols. Lipids are characterized by their insolubility in water. They are found in nuts, seeds, oils, butters, meat, fish, and germs of some grains. Lipids are composed of carbon, hydrogen, and oxygen (like carbs). Because lipids have many more carbons and hydrogens in proportion to their oxygens, they can supply more energy per gram than carbohydrates can.
Hydrolysis
uses a molecule of water to break a disaccharide into two separate molecules. reaction for breaking down glycogen into glucose. The complete breakdown of glucose yields water and carbon dioxide.
