NTR Midterm review, Chapters 1-7 and quizzes with verified solutions., Exams of Nutrition and Aging

Download NTR Midterm review, Chapters 1-7 and quizzes with verified solutions. and more Exams Nutrition and Aging in PDF only on Docsity! NTR Midterm review, Chapters 1-7 and quizzes with verified solutions. Nutrition is the branch of science that ONLY focuses on identifying the nutrients that are in foods. - ANS false Which of the following individuals have the training, expertise, and education necessary to provide accurate nutrition information and recommendations? (Select 2) - ANS correct: - PhD-level (Degreed) Nutritionist - Registered Dietitian Incorrect: - Certified Nutritionist - Personal Trainer - Nutritional Consultant What is an essential nutrient? - ANS correct: - A nutrient that is needed but must be obtained from food (because the body cannot make it). Incorrect: - A nutrient that you can only get from supplements. - A nutrient that is helpful but not needed. - A nutrient that is needed but can be made by the body. Which of the following substances are inorganic (select 2)? - ANS correct: - Minerals - Water Incorrect: - Vitamin A - Lipids Which of the following substances does not provide energy? - ANS correct: -minerals Incorrect: - Proteins - Alcohol - Carbohydrates What essential nutrient is involved in nearly all body processes (like metabolic reactions, fluid balance, nerve impulses, muscle contractions, and nutrient transport)? - ANS correct: - Water Incorrect: - Oxygen P a g e 1 | 50 - Vitamin D - Carbon A half-cup of vanilla ice cream contains 29 grams of carbohydrate, 2 grams of protein and 20 grams of fat. How many total kilocalories does this ice cream contain? - ANS answer: - 304 kcals (calories) Steps: A veggie burger patty is 136 kilocalories and contains 15 grams of carbohydrate, 10 grams of protein and 4 grams of fat. What percentage of the energy in the burger comes from carbohydrate? - ANS answer: - 44% Steps: The AMDR for protein is between - ANS correct: - 10-35% of total energy intake Notes: The AMDR for carbohydrate is between - ANS correct: - 45-65% of total energy intake Notes: A person is 'doing keno' and consumes 20 g of carbohydrates/day in a 2000 kilocalorie diet. How does this amount fit with the AMDR? - ANS correct: - It's below the AMDR Why: The pack of cookies that your roommate purchased has the following nutrients facts panel: - Serving Size: 32g (3 cookies), - Servings per Container 11 - Calories 160 - Total Fat 8g, Saturated fat 2.5g, Cholesterol 0mg, and Trans Fat 0g - Sodium 105mg - Total Carbohydrate 21g - Added Sugars 15g - Dietary Fiber 1g - Protein 2g If your roommate ate 9 cookies, how many kilocalories would she consume? - ANS answer: 480 kcals Steps: P a g e 2 | 50 CCK then simulates the pancreas to release bicarbonate and enzymes. It also stimulates the gallbladder to release bile. All of these processes begin to break down the fat in the small intestine. The partially digested fat no longer stimulates CCK release. If there is no CCK, then the pancreas and gallbladder are not stimulated and nothing is released. What type of homeostatic feedback loop is this situation describing? Fiber - ANS non-digestible carbohydrates that promote GI health, increase satiety, and reduce risks of heart disease, diseases, and some cancers? Small intestine - ANS where does chemical digestion of table sugar (sucrose) begin? Functions of each component of the digestive tract. Illeocecal valve - ANS allows passage of chime from the small intestine to the large intestine Functions of each component of the digestive tract. Epiglottis - ANS protects airway during swallowing Functions of each component of the digestive tract. Lumen - ANS continuous space that carries nutrients through the GI tract that are waiting to be absorbed Functions of each component of the digestive tract. Pyloric sphincter - ANS releases small portions of chime from the stomach into the small intestine What monosaccharide has the sweetest taste? - ANS fructose Which of the following are considered to be polysaccharides? (Select 3) - ANS - starch - Glycogen - Fiber Which of the following provides carbohydrates in the diet? - ANS - all of these foods are sources of carbohydrate: Fruit, grains, beans, vegetables Which of the following locations doe’s enzymatic (chemical) digestion of carbohydrates take place? (Select 2) - ANS small intestine and mouth What is the common name of the disaccharide molecule that contains glucose + GA lactose? - ANS milk sugar Which statement is true about polysaccharides? - ANS true: P a g e 5 | 50 - Chemical digestion of starch begins in the mouth False: - Starch is indigestible. - Fiber is the storage form of glucose in the body. - Glycogen is the storage form of glucose in plants. What are the recommended dietary strategies for individuals with lactose intolerance? (Select 2) - ANS - Gradually increase milk intake & consume it with other foods - Consume yogurt or lactose-free milk Brain - ANS organ is the primary user of glucose in the body? Insulin and glucagon - ANS When blood glucose rises, the pancreas secretes ________ to promote glucose update into the cells. However, when blood glucose falls, the pancreas secretes ________ to breakdown glycogen into glucose for use. When we consume inadequate amounts of carbohydrates (<50 g/d), how does the body respond? (Select 2) - ANS correct: - Fat gets broken down to form ketone bodies (for fuel) - Protein gets broken down to form glucose Wrong: - Fiber gets broken down to form glucose - We immediately go into cardiac arrest and die The primary reason why a diet high in added sugars is 'harmful' is because the foods/beverages containing the added sugar are nutrient poor but energy dense and displace the consumption of nutrient dense foods. - ANS true The recommended fiber intake in adults is - ANS 25 g/day for women 38 g/day for men Prediabetes - ANS If you have a fasting blood glucose of 115 mg/ld., what range are you in 50% - ANS What percent of the grains that you consume should be whole grains? False - ANS Fiber supplements are just as effective as consuming fiber-rich foods. Which energy-yielding nutrient supplies about 60% of the body's energy needs during rest? - ANS fat What are the 3 types of Lipids? (Select all that apply) - ANS Triglycerides Phospholipids Sterols P a g e 6 | 50 Not: Monosaccharides Polypeptides Triglycerides are made up of: (Select all that apply) - ANS - 3 fatty acids - Glycerol Not 1 fatty acid/amino acids Which type of fatty acids have double bonds (and thus less hydrogen’s on their chemical backbone) which contribute to their protective nature in reducing the risk of chronic disease? - ANS Unsaturated Fatty Acids Which of the following blood lipids are associated with an increased risk of chronic disease? (Select 2) - ANS - LDL cholesterol - Triglycerides The health effects of dietary fats are only dependent on the quantity that is consumed. - ANS false Which of the following statements are true about polyunsaturated fats? (Select 3) - ANS - spoils readily - Liquid at room temperature - lowers LDL blood cholesterol Which of the following statements are true about saturated fats? (Select 3) - ANS - more resistant to oxidation - contributes to elevated LDL blood cholesterol - Solid at room temperature Which of the following is NOT true of high density lipoprotein (HDL)? - ANS not true: - deliver triglycerides to cells True: - synthesized in the liver - Exhibit anti-inflammatory properties - removes cholesterol from cells Which of the following is NOT true of very low density lipoprotein (VLDL)? - ANS not true: - removes cholesterol from cells True: - Acts as "water taxi" for triglycerides, delivering lipids to body cells - synthesized in the liver - Eventually becomes LDL What substance is released from the gall bladder and binds to the large fat globules in the lumen of the small intestine, breaking them into smaller "emulsified fat" droplets? - ANS bile P a g e 7 | 50 Six classes of nutrients - ANS - Protein, carbohydrates, lipids, vitamins, minerals and water - Energy-yielding: body uses for energy - Essential nutrients: must be provided by diet Other contents that food contains - ANS - Phytochemicals: compounds from plants - Pigments, additives, alcohols, etc. The body contains - ANS - Water: 60% - Fat: 18-21% (men); 23-26% (women) - Other nutrients: the rest Macronutrients - ANS - Required in relatively large amounts - Energy-yielding - Carbohydrates, lipids, proteins Micronutrients - ANS - Required only in small amounts - Vitamins and minerals Alcohol does not equal nutrient - ANS Interferes with growth, regulation and repair of body Energy from food = - ANS kilocalories = calories = calories Total food energy (i.e. calorie content) depends on nutrient distribution - ANS - Carbohydrate = 4 kcal/g - Protein = 4 kcal/g - Fat = 9 kcal/g Most foods are - ANS a mixture of energy-yielding nutrients Exceptions to mixture of energy-yielding nutrients - ANS sugar (pure carbohydrate) and oil (pure fat) Vitamins, minerals and water do NOT provide - ANS energy/calories Energy-yielding nutrients (using nutrients for energy) - ANS Bonds between nutrients atoms break -> energy released - Heat and energy for body functions Excess energy: storage (e.g. fat) - Used between meals and overnight - Increased energy in storage = weight gain Other roles - Materials for building body tissues - Regulation of bodily activities: digestion, energy metabolism Carbohydrates - ANS - Primary source of fuel for the body (especially for brain function and physical exercise) - Composition: chains of carbon, hydrogen and oxygen P a g e 10 | 50 - Common foods: grains (wheat, rice), vegetables, fruits, legumes (lentils, beans, peas), seeds, nuts and milk products Lipids - ANS - Insoluble in water - Major form of stored energy *Stored as adipose tissue (body fat)*Energy source during rest or low- to moderate intensity exercise* - Provide fat-soluble vitamins and essential fatty acids - Include triglycerides, phospholipids and sterols - Composition: carbon, hydrogen and oxygen - Common foods: oils, animal fats, seeds and nuts Proteins - ANS - Support tissue growth, repair and maintenance - Composition: amino acid chains of carbon, hydrogen, oxygen and nitrogen - Common foods: primarily in meat, dairy, seeds nuts and legumes *Small amounts also found in vegetables and whole grains* Vitamins - ANS - Organic molecules (contain carbon) - Do not supply energy to our bodies - Micronutrients (required in smaller amounts) - 13 vitamins assist in regulating various body processes *Facilitate the release of energy from carbohydrate, fat, protein (metabolism)*Build and maintain healthy bones and tissues*Support immune system*Ensure healthy vision* - Vulnerable to destruction: heat, light and chemical agents Minerals - ANS - Inorganic substances (do not contain carbon) - Do not supply energy to our bodies - Food and the body contain major minerals and trace minerals - 16 minerals essential for body processes: *Regulate fluid balance*Assist in energy production *Essential for bone and blood health* - Indestructible not vulnerable to heat, light or chemical agents Water - ANS - Inorganic (does not contain carbon) - Essential nutrient - Water is involved in nearly all body processes: Metabolic reactions, Fluid balance and nutrient transport, Nerve impulses, Body temperature, Muscle contractions, Nutrient transport, Excretion of waste products Determinants of health? - ANS Nutrition, lifestyle, environment, genetics, medical care What is NOT the science of nutrition - ANS - NOT about our food preferences? - NOT about identifying good food and bad food (eat this, not that) - NOT about how (eating) food impacts the environment - NOT about our opinions or beliefs about nutrients or foods The science of nutrition - ANS - The integration of many other sciences: Biology, Chemistry, Anatomy and Physiology P a g e 11 | 50 - Nutrition is the branch of science examining: the nutrients in foods and (their actions within the body)/ (impact on health) - All nutrition recommendations and guidelines developed from scientific evidence! Observational studies - ANS Studies in which large groups of people are observed - Investigators do not interfere or try to influence health outcomes - Used to identify a relationship between a (nutrition) factor and health (or disease) - Large registries and databases Types of data (examples): - Proportions of individuals - Frequency of consumption - Correlational data Experimental studies - ANS Studies in which a change in diet, nutrient or eating behavior is prescribed - Investigators do interfere and try to influence health outcomes - Used to identify a cause and effect between a (nutrition) factor and health (or disease) - Human clinical trials: large (1,000s) or small (n=10) - Must have a control group to compare to Types of data (examples): - Dose response - Multiple treatments - Multiple groups Dietary Reference Intakes (DRIs) - ANS - Standards that define the amount of energy, nutrients and water intake to best support health - Developed by the Institute of Medicine (IOM) - Recommendations apply to healthy people - Continually updated DRI's 4 main components - ANS 1. Estimated average requirements (EAR) 2. Recommendation dietary allowance (RDA) 3. Adequate intake (AI) 4. Tolerable upper limits (UL) Estimated average requirements (EAR) - ANS Average daily amount of a nutrient required to maintain health in 50% of healthy adults - Differs by group: age, sex If someone consumes less than requirement: - Nutrient stores decline - Can lead to health problems Recommendation dietary allowance (RDA) - ANS Average daily amount of a nutrient recommended as adequate to meet the nutrient needs of most healthy people - EAR is needed to set the RDA - The RDA goal is for most people - Set high to make sure 98% healthy people will not be deficient - Differs by group: age, sex P a g e 12 | 50 - USDAs Continuing Survey of Food Intakes by Individuals (CSFII) What We Eat in America (combination of both surveys above) - Data used for: public policy; research; product development; establishing national health goals National health goals - Healthy people programs: increase the quality the quality and years of healthy life; eliminate health disparities - Healthy eating index (HEI) score: whether Americans are meeting guidelines Dietary principles - ANS 1. Adequacy: energy (kcals) and nutrients 2. Balanced diet: enough but not too much and different types of foods to meet recommendations 3. Energy balance: energy intake = energy expenditure 4. Nutrient density: ratio of recommended nutrients: total energy - High nutrient density = most nutrients for fewest kcals - Low nutrient density = high energy density, least nutrients for greatest kcals 5. Moderation: consume low-nutrient dense, high-energy dense foods occasionally - Ultra - processed foods (added ingredients) - High: sodium, added sugar and or saturated fats *Remember less than or equal to 15% of your diet* 6. Food-first mentality: all nutrient needs can (and should) be fulfilled with foods, not supplements for most individuals 7. Portion size: use portion size guides, choose smallest, ID portion sizes on packages, significantly increased over the past 20 years 8. Variety: increased variety within food groups as not all foods are 'created equally' 3 example patterns within the DGAs - ANS - Healthy US-style dietary pattern - Healthy vegetarian dietary pattern - Healthy Mediterranean-style dietary pattern Healthy Dietary Patterns - ANS - All patterns are 'plant-based' with the majority of calories and foods coming from plants - Vary in the amounts and types of foods included - All patterns limit the amount of added sugar, saturated fat and alcohol Diet Planning Guides - ANS - Need tools and knowledge to plan an ideal diet USDA food patterns: assign foods to five major groups - Recommended daily amounts for each food group - Notable nutrients - Serving equivalents (ounces, cups, etc.) - Nutrient density USDA food patterns - ANS - Notable nutrients - Discretionary calorie allowance (85-15 rule) - Serving equivalents - Mixture of foods Unique diets: vegetarians and ethnic food choices My Plate (website) - ANS - Combines USDA food patterns and dietary guidelines - Educational tools on website P a g e 15 | 50 - Allows for personal planning: height, weight, age, sex, activity level, different phases in lifecycle - Addresses pyramid shortcomings: visual reminder for every meal My Plate Shortcomings - ANS - Not enough information on graphic - Website contains much more detail: Balancing calories, Foods to increase, Foods to reduce Food patterns - ANS sort foods by micronutrient content Food lists - ANS group foods by macronutrient content Putting the plan into action - ANS - Familiarize yourself with each food group - Assign foods from each group into meals and snacks - Aim for nutrient-dense choices Grocery shopping - ANS - Consider foods you enjoy - Make improvements little by little - Processed foods Grains (shopping) - ANS Whole-grain products - Highest nutrients and dietary fiber - Favorite whole grain product Enriched - Replaces some nutrients lost during processing - Doesn't replace all lost nutrients or dietary fiber Refined - Lost many nutrients and fiber - Favorite refined grain product? Protein foods (shopping) - ANS - Meat, poultry, seafood, eggs, legumes, nuts, seeds, soy products - Portion sizes - Reduce fat Milk and milk products (shopping) - ANS Fortified and low-fat options Vegetables and fruits (shopping) - ANS - Think variety, think color - Fresh v canned, frozen or dried - Juices Food labels - ANS - Generally required for all packaged foods (with exceptions) - Ingredient list - Nutrition facts label Nutrition facts label - ANS - Quantities * Serving size (#)*Energy (kcal)*Nutrients (g or mg) or % Daily Value* - Macronutrients *Sub-categories* - Select micronutrients (nutrients of concern) P a g e 16 | 50 Nutrient claims - ANS meet FDA definitions Health claims - ANS Relationship between food and disease or health condition Structure-function claims - ANS Made without FDA approval; avoids specific disease Digestion - ANS Breaking down foods into nutrients Gastrointestinal (GI) tract (digestion) - ANS - Flexible and muscular tube with a continuous inner space (lumen) - Extends from mouth to anus - Simplified path: mouth -> esophagus -> stomach -> small intestine -> large intestine -> rectum -> anus Mouth (digestion) - ANS Process of digestion begins - Mastication (chewing) to break apart food and mix it with saliva - Eases swallowing Taste perceptions: - Five basic taste sensations: sweet, sour, bitter, salty, umami - Aroma, appearance, texture and temperature Pharynx (both digestion and respiration) Epiglottis - Closes airway and prevents choking Bolus: food that has been chewed and swallowed Esophagus (digestion) - ANS Two sphincters - Upper esophageal sphincter (throat) - Through hole in diaphragm - Lower esophageal sphincter (entrance to stomach) Stomach (digestion) - ANS Movement of bolus: upper to lower portion of stomach, mixes with digestive juices - Bolus -> chime (acidic, semiliquid mass) Pyloric sphincter - Releases small portions of chime into small intestine Small Intestine (digestion) - ANS Bypasses common bile duct - Drips fluid (made by pancreas and gallbladder) into small intestine Travels down three segments: duodenum, jejunum, ileum - About 10 feet long Large Intestine (digestion) - ANS - Ileocecal valve (sphincter) - beginning of colon - Colon segments: ascending -> transverse -> descending -> sigmoid - Withdrawal of water from chime - Rectum (strong muscle) - Anus (two sphincters) GI motility: movement of digestive tract - ANS - Circular muscles (inside small intestine) P a g e 17 | 50 Bloodstream - ANS - Water-soluble nutrients and smaller products of fat digestion - Guided directly to liver Lymphatic system - ANS - Larger fats and fat-soluble vitamins (insoluble in water) - Intestinal cells assemble products of fat digestion into larger molecules, cluster with proteins to become: Chylomicrons (fat transporters) - umber for fat molecules - Bypass liver at first Vascular System - ANS CLOSED SYSTEM OF VESSELS - Continuous blood flow - Heart = pump BLOOD - Delivers oxygen and nutrients to body tissues - Removes carbon dioxide and wastes from body tissues - Normal blood flow: Heart -> arteries -> capillaries -> veins -> heart - Special route for digestive system blood: Heart -> artery -> capillaries (in intestines) -> hepatic portal vein -> capillaries (in liver) -> hepatic vein -> heart - Liver = hero! *Direct to receive nutrients from GI tract (before heart)*Prepares absorbed nutrients (carbohydrates, fats, proteins, etc.) for use in the body*Detoxifies harmful substances; prepares waste for excretion* Lymphatic system - ANS One-way route, flows toward heart - No pump - Circulation between cells in response to body movement Entry into bloodstream - Collects in thoracic duct (behind heart) -> subclavian vein -> bloodstream Nutrients in lymphatic vessels - Large fats and fat-soluble vitamins - Bypass liver at first Who is the superhero of the digestive system? - ANS Liver Gastrointestinal micro biota (gut flora) - ANS 100 trillion microbes: bacteria, viruses, fungi, protozoa, etc. Bacteria alone: 400 species and subspecies Factors influencing micro biota: - Diet: short and long term choices - Plant-based diet: high fiber = energy source for beneficial bacteria - Obese people: less diverse gut microbial life - Prebiotics: encourage bacterial growth and activity - Probiotics: live microbes that change GI conditions in positive way Potential benefits of GI microbes: - ANS alleviate/prevent: constipation, diarrhea, inflammatory bowel syndrome, inflammation, ulcers, allergies, lactose intolerance, colic (infants) enhance immune function; protect against colon cancer; lower blood cholesterol; lower blood pressure P a g e 20 | 50 (Endocrine and nervous systems) Homeostatic regulation - ANS Body should maintaining "business as usual" - Hormones (endocrine) and nerve pathways (nervous system) coordinate all digestive and absorptive processes - Stimulation and inhibition of digestive secretions as food travels through GI tract (Endocrine and nervous systems) Feedback mechanisms - ANS GI hormones regulate digestion and absorption with negative feedback loops Gastrin - ANS secreted by cells in stomach wall Secretin - ANS secreted by cells in duodenum wall Cholecystokinin (CCK) - ANS secreted by cells in intestinal wall The digestive system at its best - ANS Sensitive and responsive to environment - GI tract cells provide immunity against intestinal diseases - Secretions defend against foreign invaders Health of digestive system - Healthy supply of blood - Lifestyle factors: sleep, physical activity, stress - Types of foods eaten: Balance, moderation, adequacy and variety Choking - ANS Food slips into trachea - Cuts off breathing International sign for choking - Heimlich maneuver Foods commonly associated with choking - Meat (chunks), hot dogs, nuts, grapes, carrots, marshmallows, hard candy, gum, popcorn, peanut butter Prevention of choking - Small bites, chew thoroughly, don't talk/laugh/breathe heavily while eating Vomiting - ANS Adaptive mechanism of the body - Get rid of irritants Medical treatment - Dehydration and loss of salt - Repeated vomiting = damage to esophagus, salivary glands, teeth, gums Diarrhea - ANS Intestinal contents move too quickly, Dehydration and loss of salt, Symptom of medical conditions - Irritable bowel syndrome (IBS): identify and avoid irritating foods - Colitis: avoid greedy foods, milk products and high-fiber foods - Celiac disease: gluten-free diet Constipation - ANS - Symptom, not a disease - Symptoms of constipation: straining, hard stool, infrequent bowel movements, discomfort, headaches, backaches, passing gas - Causes: lifestyle "too busy," side effect of medications P a g e 21 | 50 - Prevention: Fiber (25g - 28g), water and physical activity Belching - ANS - Swallowed air - Prevention: eat slowly, chew thoroughly, and relax Intestinal gas - ANS Consumption of certain foods - Individually determined - Common offenders: foods rich in carbohydrates - Sugars, starches, fibers Gastro esophageal reflux - ANS - Heartburn - Indigestion - Repeated acid splashes = damage to esophagus Heartburn - ANS - Causes: overeating/overdrinking; body position; medications; smoking; weight gain - Prevention: eat less, chew thoroughly, and eat slowly Indigestion - ANS - Causes: unthawed/too much food in stomach, disrupts peristalsis - Antacids and acid controllers: use only infrequently Repeated acid splashes = damage to esophagus - ANS Barrett's esophagus; increased cancer risk Ulcers - ANS Peptic ulcers = lesions in lining of: - Stomach = gastric ulcer - Duodenum = duodenal ulcer Causes - Bacterial infection = most common - Anti-inflammatory drugs - Excessive gastric acid secretion Ulcer treatment regimen - Treat for infection; eliminate foods that exacerbate discomfort; avoid coffee, caffeine, and alcohol Carbohydrates (CHO) sugars, starches, fibers - ANS - Sources of carbohydrates: plant foods (grains, vegetables, fruits and legumes) and milk - "Fattening" - not necessarily! Brain and red blood cells (carbs) - ANS Fueled by glucose Muscles energy for movement - ANS - Glycogen (stored form of glucose): 50% - Fat: 50% Monosaccharide’s (single sugars) - ANS - Simple carbohydrates - Chemical composition: C6H12O6 - Glucose, fructose, GA lactose - Most abundant monosaccharide in nature P a g e 22 | 50 *Polysaccharides (starch) (remainder) - amylase -> smaller polysaccharides, disaccharides, monosaccharide’s* *Disaccharides - 'aces' -> Monosaccharide’s* CHO digestion - large intestine - ANS - None - Only 1 thing left: fiber - Fermentation: *Bacteria -> enzymes -> fiber* *Non-digestible polysaccharides (fiber) - bacterial enzymes -> Water (soften stools), Gas, Short-chain fatty acids -> Energy (colon) CHO digestion - resistant starches - ANS - CHO-rich foods that are poorly digested - Pass through the small intestine - In the large intestine, they act like a fiber - May prevent some chronic diseases: diabetes, colon cancer, obesity CHO digestion - FODMAP - ANS Fermentable Oligosaccharides, Disaccharides, Monosaccharide’s And Polios - CHO-rich foods that are poorly digested - Pass through the small intestine - Fermented by bacteria in colon: Gas, diarrhea/constipation Glucose and GA lactose transport - ANS active transport and requires energy (ATP) -> blood -> body Fructose transport - ANS facilitated transport and no energy is needed -> blood -> liver Lactose intolerance - ANS Defined: reduction in lactose digestion Symptoms of intolerance - Increase in water and feeds GI bacteria (large intestine) - Bloating, abdominal discomfort, gas, diarrhea Cause: reduction in lactase - Age - Genetics - Diseases/Medications - Dietary habits Lactose Intolerance - dietary strategies - ANS - Manage dairy consumption rather than eliminate - Most can tolerate 6 g lactose (½ cup milk) - Gradually increase milk intake (with other foods, etc.) - Consume yogurt or lactose free milk - Tolerance varies - individualize diet Daily recommendation (added sugar) - ANS less than 25g Digestion -> absorption -> - ANS metabolism: biochemical processes that provide energy to living cells (Blood -> cells -> energy) P a g e 25 | 50 Carbohydrate (CHO) metabolism pt. 1 - ANS - Glucose = central focus of carbohydrate metabolism - Glycogen = stored form of glucose - Condensation (linking) reactions turn glucose -> glycogen (when blood glucose rises) - Hydrolysis (breaking) reactions turn glycogen -> glucose (when blood glucose falls) - Liver = stores ¼ of total glycogen *Released into blood as needed*enough in storage for about one day* - Muscles store ¾ of total glycogen *Hoards glycogen for use during exercise* - Brain stores small amount of glycogen (for emergencies) Carbohydrate (CHO) metabolism pt. 2 - ANS Glucose = energy for most cells - Especially brain, nerve cells and developing red blood cells - Cells break down glucose into smaller compounds (energy (ATP) released during process) Inadequate dietary carbohydrates (glucose)? - ANS - Cells convert amino acids (from protein) to glucose: Gluconeogenesis - Dietary carbohydrates play protein sparing role Fat metabolism shifts: Fat fragments combine with one another -> ketone bodies (acidic) - Provide alternative fuel during starvation - Ketone body production exceeds use = accumulate in blood -> ketosis - Ketosis disrupts body's acid-base balance - Body needs 50-100g of carbohydrates per day to spare body proteins and prevent ketosis Abundant dietary carbohydrates (glucose)? - ANS - Fat metabolism shifts - Body burns more glucose instead of fat (fat is conserved) - Body converts excess glucose into fat for storage (fat is created) - Fat cells can store almost unlimited stores of fat Primary user of glucose = brain - ANS - Uses 60% total glucose (120 grams/day; 420kcal) - When available glucose drops to half that amount, problems occur - Powers the transmission of nerve impulses and synthesizes neurotransmitters: thinking, memory, learning, initiation of movement, etc. - Can use ketones (when needed) Secondary users = muscles, liver, adipose (fat cells), kidneys, red blood cells - ANS All of these (except red blood cells) have additional energy sources to use Steady supply of glucose delivered to cells via blood stream: - ANS - Glucose brought from intestines (from food) - Glucose brought from liver (from glycogen stores or gluconeogenesis) Blood glucose: must remain in normal range for body to function (homeostasis) - ANS Regulated by hormones: - Insulin: moves glucose from blood into cells - Glucagon: brings glucose out of storage when needed P a g e 26 | 50 - Epinephrine: signals liver cells to release glucose during stress (Fight or flight response) Deficit-state (low blood glucose) - ANS pancreas secretes glucose -> liver breaks down glycogen into glucose -> normal blood glucose Surplus-state (high blood glucose) - ANS pancreas secretes insulin -> cells take in glucose, liver stores glycogen -> normal blood glucose The constancy of blood glucose - ANS Balancing within the normal range: dependent on food and hormones - Key = balanced meals (with carbohydrates) at regular intervals Irregularities in blood glucose levels - ANS - Diabetes: high blood glucose (hyperglycemia) - Insulin is either inadequate or ineffective - Type 1 diabetes: pancreas doesn't produce insulin - Type 2 diabetes: cells do not respond to insulin (related to obesity) - Hypoglycemia: low blood glucose (rare - usually result of poorly managed diabetes) Glycemic response - ANS - How quickly glucose is absorbed, how high blood glucose rises and how quickly blood glucose returns to normal levels - Low glycemic response (desired) *Slow absorption, modest rise, smooth return to normal* - High glycemic response (less desirable) *Fast absorption, surge, plunge* - Glycemic index: categorizes foods based on glycemic response elicited Glycemic index of selected foods - ANS - Pros: low glycemic index foods may improve glucose control and lower diabetes risk - Cons: hasn't been determined for many foods; people have different glycemic responses to the same food; isn't intuitive or listed on nutrition labels; is variable depending on plant variety, cooking/processing method, time of day consumed and consumed with other foods - May be unnecessary: current guidelines already suggest eating low glycemic foods Health effects of sugars - ANS - Pleasure in moderate amounts - Average US diet contains too much - Moderate intake is not detrimental to health...moderation is hard! Sugar provides glucose and energy (calories) but few nutrients - ANS Difficult to have high sugar diet + necessary proteins, fiber, vitamins and stay within calorie limit - Sugar displaces nutrients - Mom was right...eat your veggies before your dessert! Amount of "allowable" sugar depends on available discretionary calorie Honey - ANS - Natural does not equal healthy - Similar composition to table sugar (glucose + fructose) - Density: more energy per spoonful than table sugar - Contains a few vitamins and minerals P a g e 27 | 50 Obesity and the link to carbohydrates - ANS - Total daily energy intake has increased - Activity levels have declined - Body weight has increased - Restricted calorie intake = weight loss (regardless of which energy nutrient is restricted) Increase in consumption of added sugars - ANS - High-fructose corn syrup - High sugar intake = increased body fat stores Moderation of sugar intake is challenging - ANS - Sugary foods and drinks: cheap, available, easy to consume and tasty - Self-imposed labeling of foods: bad foods are harder to resist! Carbohydrate addictions/cravings: - Not physiological or pharmacological - Increases serotonin in brain (elevates mood) - May stimulate brain regions associated with attention and reward Metabolism - ANS Glucose moves directly to body cells - Stimulates insulin release -> appetite is suppressed Fructose must be converted to glucose (by the liver) - Excess fructose can burden the liver - Excess added sugars become fat (retained in liver or sent to blood and body fat stores) - Does not immediately stimulate insulin release -> appetite is not suppressed Food form impacts fullness - Liquid: provides energy but not fullness - Solid: provides energy and fullness Insulin's response - ANS Surge of insulin levels after meals - Glucose moved into cells; fatty acids stored as fats; protein synthesis - Cell's response to insulin = critical to maintain health Glycemic effect of food - Varies depending many factors: food processing, how food is eaten, etc. Positive association between diets with high glycemic index and body weight - Insulin response varies across people All carbs are not equal (or evil) - Limit added sugars: HFCS and sucrose - Not necessary to cut out all carbohydrates (fruits, veggies, whole grains Poor health can result from - ANS - Too much fat - Too little fat - Too much of some kinds of fat Lipids include - ANS - Triglycerides (fats, oils) - Phospholipids - Sterols Triglycerides (fats, oils) - ANS - Most abundant in foods and the body P a g e 30 | 50 - Fat does not equal lipid - One glycerol and 3 fatty acids - Glycerol backbone - formed via condensation reactions (H from glycerol + OH from fatty acid = new bond and H2O) Lipids composition - ANS - carbon, hydrogen, oxygen - More carbons and hydrogen’s than oxygen’s - More energy provided per gram Calories for lipids v carbohydrates and proteins - ANS L: 9 calories/gram C&P: 4 calories/gram Fatty acids - ANS - even number of carbons - Saturated or unsaturated - Omega 3 and omega 6 fatty acids: body cannot synthesize - Organic acid - Usually even # of carbons Methyl group at one end (fatty acid) - ANS CH3 Acid group at other end (fatty acid) - ANS COOH Long-chain - ANS greater than 12 carbons Medium-chain - ANS 8-12 carbons Short-chain - ANS 6 carbons Saturated - ANS full of hydrogen’s Unsaturated - ANS - missing hydrogen’s - Double bond C Double bond C - ANS point of unsaturation Monounsaturated - ANS 1 double bond C Polyunsaturated - ANS 2 or more double bond C Polyunsaturated fatty acids identified by - ANS location of double bonded C's Omega number is the position of double bond neatest methyl end of carbon chain - ANS - 3C away from CH3 = omega 3 (linoleic acid) - 6C away from CH3 = omega 6 (linoleic acid) Monounsaturated fatty acids - ANS 9C away from CH3 = omega 9 (oleic acid) Chemical composition of fats - ANS - existence, number and location of double bonded Cs P a g e 31 | 50 - influences characteristics of fats and oils in foods Degree of unsaturation (# of double bonded Cs)/firmness at room temperature - ANS - polyunsaturated fats (most from veggies) = liquid - Saturated fats (most from animals) = solid - Saturated fats (from plants) = solid softer... Oxidation - ANS spoilage of fats - Polyunsaturated spoil quickly (many double bonded Cs = unstable) - saturated keep longest (no double bonded Cs) Manufacturer options for protecting against oxidation - ANS - expensive storage - Addition of antioxidants - Hydrogenation Hydrogenation - ANS - hydrogen molecules added to points of unsaturation (becomes saturated) - Advantages: longer shelf life (less oxidation), alters textures of fats - Disadvantages: partially hydrogenated = some double bonds change from cist -> Trans configuration Total hydrogenation - ANS rarely occurs in food processing Cist - ANS H next to double bonds on same side of carbon chain Trans - ANS H next to double bonds on opposite sides of carbon chain Body processes trans-fat like saturated fat - ANS Increase blood cholesterol and heart disease risk Phospholipids - ANS - 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 - Part of cell membranes - Vitamin and hormone transport in/out of cells - Emulsifier: keep fat suspended in blood Sterols - ANS - Multiple-ring structure FOOD SOURCES: - Cholesterol: animal sources (meat, eggs, seafood, and poultry, dairy) - Plant sterols: structurally similar to cholesterol -> interfere with cholesterol absorption -> lower blood cholesterol - Vital body compounds made from cholesterol: bile acids, sex and adrenal hormones, vitamin D, cholesterol - 90% of body cholesterol = in cells (does not equal 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 P a g e 32 | 50 - Hormone-sensitive lipase -> TG -> FA (circulation) - FAs can be used by liver and muscle - FAs cannot be converted to glucose (issue?) - FAs can be converted to Ketone Bodies Blood lipid profile - ANS lipids that are circulating in the blood Health risks - ANS cardiovascular (heart) disease, stroke, etc. Do dietary lipids impact health? - ANS - Depends - Triglycerides - YES, cholesterol - no Cardiovascular heart disease - ANS - Saturated fat increasing blood LDLs & TGs - Trans-fat increasing LDLs and TGs; lowering HDLs - Dietary cholesterol: impacts blood cholesterol very little, if at all Cancer - ANS - Saturated fats and fats from fatty or processed meats pose highest risk - Promotion rather than initiation of cancer - Differs for various types of cancer: colon cancer has strongest association Obesity - ANS Fat yields highest amount of energy (9 kcals/gram) Why does dietary cholesterol have little to no effect on circulating cholesterol (in most people)? - ANS - Circulating cholesterol is tightly controlled - 60% of adults don't see any increase - 40% are hyper-responders (genetics) - Most see and increase (in LDL size) but not harmful - Increase of HDL at the same time - Ratio of LDL: HDL stays the same How do fats impact circulating cholesterol? - ANS - Saturated fats increase LDL- cholesterol - MUFAs & PUFAs decrease LDL-cholesterol Omega-3 fatty acid: linoleic acid - ANS - Polyunsaturated essential fatty acid - Body can synthesize other omega-3s if given linoleic acid - Without it, other omega-3s become "conditionally essential" DHA (docosahexaenoic acid) EPA (eicosapentaenoic acid) ROLES: - Anti-inflammatory (improves heart health) - Structure and function of cells (eyes and brain) - Growth, acuity and cognitive development - Protective effects: cancer, asthma, pancreatitis, rheumatoid arthritis Omega-6 fatty acid: linoleic acid - ANS - Polyunsaturated essential fatty acid - Body can synthesize other omega-6s from linoleic acid ROLES: - Pro-inflammatory P a g e 35 | 50 - Structure and function of cells (brain) - Growth, acuity and cognitive development - Focus less on reducing omega-6s and more on increasing omega-3s - Balanced ratio of omega 6/omega 3 is important Essential Fatty Acids & Health Risks (Deficiencies) - ANS - Most Americans meet minimum requirements WHEN DEFICIENCY OCCURS: - Skin problems (dry, itchy, flaky) - Slow growth - Reproductive failure - Kidney/liver disorders - Neurological and vision problems Current Dietary Fat Intake in the US - ANS - Health effects of dietary fat depend on quantity and quality - 33% of daily energy intake from fats - 12% of daily energy intake is from saturated fat - Omega 6 to omega 3 ratio: as high as 20/1 Recommended Dietary Fat Intake - ANS - Dietary reference intakes (DRI) - No RDA or AI for total daily dietary fat (ages 1+) - AMDR: 20-35% of daily energy from fat - AIs set for essential fatty acids - Linoleic acid (omega-6): 5-10% daily energy intake - Linoleic acid (omega-3): 0.6-1.2% daily energy intake - Proposed 'optimal' ratio of omega 6/omega 3: between 1/1 to 4/1 Dietary guidelines for Americans - ANS - <10% from saturated fat - As little trans-fat as possible - As low dietary cholesterol as possible (specific amount has been removed) - 2 or more servings of cooked seafood per week for ages 2+ years Replace saturated and Tran’s fats with - ANS mono- and polyunsaturated fats whenever possible - Include more omega-3 fats from dietary sources Fats provide - ANS - energy - Fat-soluble vitamins: A, D, E and K - Flavor, texture, and palatability of food Proteins - ANS - Animal fats (excerpt fish) tropical oils = higher in saturated fat -- Lean choices are key - Vegetable fats = higher in mono- and poly-unsaturated fat - Eggs = good source of protein and healthy fat -- Omega-3 enriched eggs - Milk and milk products = low-fat or fat-free options have less saturated fat -- Cheese = doesn't seem to raise LDL cholesterol -- Yogurt and other fermented dairy = may lower blood cholesterol P a g e 36 | 50 Vegetables, fruits and grains - ANS - Naturally low in fat -- Avocados and olives = unsaturated fat - Lowers consumption of various fats in the diet Look for fat carefully - ANS - Invisible fat: marbled meat, fried foods, baked goods - Discretionary calories: solid fats (saturated fatty acids) - Trans-fat should be included in saturated fat allowance (10% or less of daily energy intake) Fat replacers (e.g. Olestra) - ANS - Artificial fats: sensory and cooking qualities of fat, little no calories (unique chemical structure -> passes through digestive system unabsorbed) - Vitamin-fortified options pose little risk for consumption Read food labels - ANS - Total fat: saturated fat, Trans fat - Compare products (standard labeling) - % daily value: how much a food contributes to daily fat intake -- Based on: 2000 calorie diet, 35% AMDR for fat = 78 grams/day -- Varies by personal daily calorie intake and fat AMDR (20-35%) - % calories from fat: percentage of a food's total calories that come from fat -- No longer shown on new labels Guidelines for Fake Intake - ANS - Type of fat may be more important than amount of fat - Limit saturated and Trans fat intake - Consume enough beneficial fat for health - DRI recommendations: -- Moderate calories from fat (20-35%) -- Compatible with low rates of disease Olive oil - ANS - Benefits for heart health: reducing LDL cholesterol -> domino effect - Canola and safflower oil = also healthy options - Instead of saturated fats (e.g. butter, stick margarine, animal fats) Nuts - ANS - Fat composition: 80% calories from fat -- 59% monounsaturated; 27% polyunsaturated; 14% saturated - Benefits for heart health: reducing LDL cholesterol -> domino effect - Beware of added sugars and sodium - Instead of other high-fat snack options Fish - ANS - Omega-3 fatty acids -- Benefits for heart health - Beware of environmental contaminants (e.g. mercury) - Instead of fatty meats -- Recommendation: 8 oz. /week Saturated fat = determinant of LDL cholesterol - ANS - Sources of saturated fat in US: fatty meats; whole milk products; tropical oils - Zero saturated fat is not possible - Vegan/Vegetarian diets can lower saturated fat P a g e 37 | 50 Where does most protein digestion occur? - ANS PRO digestion in stomach - ANS - Small amount of digestion (10-15%) - HCI & inactive enzyme (pepsinogen) - Pepsinogen - HCI -> pepsin (no 'as') - Polypeptide molecules - Pepsin -> smaller polypeptide chains free AAs PRO digestion in small intestine - ANS - Pancreas and small intestine -> proteases and peptidases - (Large) polypeptides - proteases -> tripe tides, dipeptides, AAs - Di & tripe tides - peptidases -> AAs PRO digestion in large intestine - ANS nothing Protein absorption - ANS Peptides can either be 1) broken down into smaller peptides or AAs or 2) transported into the intestinal cells -- Di & tripe tides can be transport without energy -- AA transporters: (like glucose) require energy - Inside the cell, di & tripe tides can be broken down into AAs - Many AAs are used by small intestine - Unused amino acids transported to liver -- Some AAs bypass liver (BCAAs) Protein metabolism - ANS - goal: have enough PRO for functional needs (see protein roles) - Pro turnover (pro formation vs. pro breakdown) = nitrogen balance - (-) 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 higher protein diets -- may be beneficial for muscle gains, etc. Protein turnover - ANS unlike CHOs or lipids, AAs are NOT stored - When AA deficient (- nitrogen balance), the body breaks down less critical protein - Small supply in blood and body cells (amino acid pool) - used for: energy, glucose, fat, ketone bodies Protein metabolism: ammonia production - ANS - Generated as a result of amino acid metabolism - Toxic compound and needs eliminated - Liver can convert it to urea (non-toxic) - Kidneys filter urea out of blood and into the urine Health effects: pro deficiency - ANS - too little total protein or lacking essential amino acids SIGNIFICANT IMPACT ON CHILDREN AND ADULTS: P a g e 40 | 50 - Reduced growth (Muscle, Bone) - Reduced physical function (Weakness, Fatigue) - Increased hunger/reduced fullness - Reduced cognitive function - Birth defects - Learning disabilities - Impaired immunity/reduced healing - Blindness - Premature death - Depression/Aggression - Hair, nail, skin issues MOST COMMON SIGN of protein malnutrition: stunted growth Health Effects of PRO Excess: Kidney/Liver Function - ANS - Increased dietary protein increases ammonia and urea production -- Increased liver function (converting ammonia to urea) -- Increased kidney function (excretes urea from body) - Evidence: 30 studies in >2,000 healthy adults -- Increased kidney filtration rate is observed BUT it's within normal ranges -- No change in protein (albumin) excretion (marker of kidney disease) - Responses are 'normal' and 'adaptive' Health Effects of PRO Excess: health risks - ANS CARDIOMETABOLIC RISKS: - No causal role of protein and CVD - No causal role of protein and Type 2 Diabetes - (+) correlation with processed and fatty meat intake and cardio metabolic risk but NOT protein - (+) correlation with protein-rich foods and protection of cardio metabolic risk CANCER: - No causal role of protein and cancer - (+) correlation with processed and fatty meat intake and cancer risks but NOT protein Health Effects: Optimizing Protein - ANS IMPROVEMENTS IN: - Weight management - Fitness/Performance - Muscle strength - Glycemic control - CVD disease risk Optimizing Protein: Muscle Protein Synthesis - ANS - Effects of increased dietary protein (AAs) + resistance exercise Health Effects: Muscle Gain and Strength - ANS - Effects of increased dietary protein + resistance exercise - Increased dietary protein (with resistance training) leads to increased lean mass and strength in healthy adults Optimizing Protein: Weight Management - ANS - Effects of increased dietary protein + energy restriction P a g e 41 | 50 -- Increased dietary protein leads to greater weight & fat loss with improvements in muscle (during energy restriction) - Effects of increased dietary protein following weight loss -- Increased dietary protein leads to less weight re-gain (following weight loss) - Effects of Increased dietary protein on food intake -- Consuming more calories from protein leads to 'voluntary' reductions in daily food intake - Increased dietary protein improves appetite control, satiety and cravings -- Down homeostatic hunger -- Down hedonic hunger -- Up homeostatic satiety -- Up hedonic satisfaction Recommended Dietary Protein Intake: - ANS Assumptions of RDA: - Healthy person - Mixed-quality protein - Energy intake is "adequate" - PRO consumed with sufficient CHOs and FATS Dietary Guidelines for Americans - Consume: Seafood Lean meats and poultry; eggs Legumes (beans and peas), nuts and seeds and soy - Limit: Red and processed meats Assumptions of source - All PRO are 'created equal' - All red meats are 'created equal' Protein Quantity - Recommended vs. Optimal - ANS RDA? Yes Optimal? No Protein Quantity - Optimal (PER Eating Occasion) - ANS Optimal intake components - 90-120 g/d - 30 g/occasion - Need more protein? - Breakfast is best Protein Quantity - Athletes - ANS - Made by the American College of Sports Medicine - Depends on type and amount of exercise PROTEIN INTAKE: - Endurance athletes: 1.2-1.4 g protein x kg body weight^-1 x day^-1 - Strength/power athletes: 1.2-1.7 g protein x kg body weight^-1 x day^-1 - During energy restriction: up to 2.0 protein x kg body weight^-1 x day^-1 What's your protein RDA? - ANS - Convert your (health) body weight in pounds to kilograms weight (lbs.)/2.2 = weight (kg) - Multiply your kg weight by 0.8 to get your RDA in grams of protein weight (kg) x 0.8 = YOUR RDA protein (g protein/day) P a g e 42 | 50 - Catabolism: bonds between atoms break = release energy Two new compounds of metabolism - ANS 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 Glucose (C6H12O6) -> pyruvate - ANS Glycolysis - "Glucose-splitting" - One glucose molecule (6 C) becomes 2 pyruvate molecules (3 C each) - Hydrogen atoms (H+) carried to an electron transport chain Pyruvate can be converted back to glucose if needed - Primarily by liver cells (kidneys) - Process = similar to glycolysis reversal Pyruvate's options - ANS Quick energy needs (e.g. sprint): anaerobic - Not requiring oxygen - Pyruvate -> lactate - Energy does not equal sustainable Slower energy needs (e.g. 10k): aerobic - Requiring oxygen - Pyruvate -> acetyl CoA - Greater energy yield (can be sustained) Pyruvate -> lactate (anaerobic) - ANS At rest: occurs to a limited extent During high intensity exercise (e.g. sprint) - Increase in pyruvate (produces ATP quickly) - Excess of H-carrying coenzymes (overwhelms mitochondria in cells) and electron transport chain can't accept H, so... Pyruvate accepts hydrogen’s - (also due to 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 blood pH, burning pain, fatigue Cori cycle: possible fate of lactate - ANS Transported from muscles to liver - Liver converts lactate -> glucose - Glucose returned to muscles Pyruvate -> Acetyl CoA (aerobic) - ANS During low intensity exercise (e.g. 10k) - Oxygen and mitochondria are available - H+ can be carried by coenzymes to electron transport chain Pyruvate enters mitochondria of cell P a g e 45 | 50 - Carbon group removed (becomes carbon dioxide) - 2-carbon compound joins with CoA; becomes acetyl CoA Irreversible (cell can't retrieve carbons from CO2 to remake pyruvate) Breaking down Nutrients for Energy: Glycerol and Fatty Acids - ANS Triglycerides: glycerol and fatty acids Glycerol -> pyruvate (or glucose) - Glycerol (3-carbon compound): can easily be converted to glucose or pyruvate (-> acetyl CoA) Fatty acids -> acetyl CoA - 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 hydrogen’s and electrons (H+) carried to electron transport chain Breaking down Nutrients for Energy: Amino Acids - ANS First step: deamination - N-containing amino group is lost - Produces ammonia + keno acid Amino acid -> energy pathway - Converted to pyruvate (glycogenic) - Converted to acetyl CoA (ketogenic) - Enter TCA cycle directly (glycogenic) Amino acids -> glucose - When carbohydrates are unavailable Acetyl CoA's options (final steps of metabolism) - ANS Synthesize fats - If ATP = abundant - Most efficient way to store energy - All energy nutrients can become ATP = all excess energy nutrients can become fat Generate high-energy compound ATP - If cells need energy and if ATP = low - Process through TCA cycle: inner compartment of mitochondria - Release hydrogen’s and their electrons (H+) -> electron transport chain TCA cycle - ANS Final common metabolic pathway for energy nutrients Circular path (one way) - Acetyl CoA (2-carbon compound) travels one way and releases: - Two carbon dioxide molecules (CO2) - One CoA enzyme - Hydrogen atoms and their electrons (H+) -> carried off by coenzymes (made from niacin and riboflavin) 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 - ANS Captures energy in bonds of ATP Series of proteins - Electron "carriers" mounted in sequence P a g e 46 | 50 - Inner membrane of mitochondria Coenzymes deliver electrons - From TCA cycle, glycolysis, and fatty acid oxidation - Electrons passed to next carrier, and next carrier, and next carrier, until... - Oxygen is reached at end of chain (necessary for energy metabolism): Oxygen accepts electrons, combines with H atoms = H2O released - ATP synthesis powered by H ions: pumped out of inner compartment, then rush back in Fat is - ANS - The most efficient fuel source - Body's preferred form of energy storage Fat yields most energy per gram (9 calories vs. 4) - ANS - 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 about 30 ATP) - More ATP = more energy Metabolism favors fat formation - ANS Regardless of excess from protein, fat or carbohydrates - Excess dietary fat -> body fat = direct and efficient (almost all excess is stored as body fat) - Carbohydrate and protein have other roles to fulfill before conversion to body fat Cells use mixture of fuels for energy - Amount of each nutrient used depends on dietary availability Excess protein - ANS - Body can't store excess amino acids (must be changed) - First: normal daily losses are replaced - Second: oxidation increases (produces energy) - Third: amino acids delaminated, remaining carbon -> ketone bodies (stored as fat in adipose tissue) Excess carbohydrates - ANS - First: storage as glycogen (limited space) - Second: oxidation increases (produces energy; prevents dietary and body fat from oxidation) - Third: converted and stored as fat Energy Balance: from feasting to fasting - ANS After and between meals... Glucose, glycerol and fatty acids = used then stored - Fasting state (2-3 hours after a meal) body draws on stores - Glycogen and fat are released -> glucose, glycerol, fatty acids for energy Basal metabolism - Energy needed to maintain life processes when body is at complete rest (physical, digestive and emotional) - ⅔ of total energy expended per day Fasting (choose not to eat) vs. starving (no choice) Energy balance: fasting - ANS Carbohydrate, fat and protein P a g e 47 | 50