Exam 1 Study Guide
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This 13 page Study Guide was uploaded by Strickland Notetaker on Friday February 5, 2016. The Study Guide belongs to NFSC100 at University of Maryland taught by Seong-Ho Lee in Summer 2015. Since its upload, it has received 106 views.
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Date Created: 02/05/16
Elements of Nutrition Exam 1 Study Guide I. The Science of Nutrition a. Nutrition: the science of food and the nutrients they contain i. The actions of nutrients include: 1. Ingestion, Digestion, Absorption, Transport, Metabolism, Excretion b. Scientific Method (Review) 1. Observation 2. Form Hypothesis: attempt at explaining observations 3. Test Hypothesis: using different study designs 4. Evaluate Study Results 5. Compare Results to Hypothesis (if proven then the theory was successful) 6. Revise Hypothesis: only if theory was not proven c. Types of Studies i. Case Studies (Individual Studies): potential interaction between nutrition and observation in a single individual ii. Epidemiological Studies (Population Studies): correlation of nutrition and observation in a population iii. Intervention Studies (Clinical Studies): experimental vs. placebo group iv. Laboratory Studies (Preclinical Studies): usage of animals in experiments d. Food Labeling i. Nutrition Labeling and Education Act (NLEA) 1990 – U.S. Federal Law, signed in 1990 gave the FDA authority over nutrition labeling and claims on most foods e. Labeling Must Contain i. serving size & serving per container ii. calories from fat per serving iii. % of daily value of fat, cholesterol, sodium, total carbohydrates, Vitamins A & C, calcium and iron iv. Daily Value reminder for 2000 & 2500 calorie diet f. % Daily Value i. Indicates how much of a specific nutrient one serving of food contains compared to daily nutrient recommendations ii. 51020% Rule 1. Below 5% considered low/poor source 2. 1019% considered a good source 3. Above 20% considered high/excellent source iii. Different depending upon whether the nutrient is beneficial or detrimental to health g. Types of Claims i. Nutrient Content Claims: level of nutrients, claim words include “free”, “low”, or “reduced”… Ex. “Reduced Fat” ii. Health Claims: already approved by the FDA based on scientific evidence … Ex. “Whole Grains reduce Cancer” iii. Structure/Function Claims: need additional scientific evidence and FDA approval, or state that “FDA has not evaluated the claim h. Nutrient Claims (describe level of nutrients within food) i. Calorie Free: less than or equal to 5 calories per serving ii. Low Calorie: less than or equal to 40 calories per serving iii. Reduced Calorie: at least 25% lower calories than regular reference food iv. Sodium Free: less than or equal to 5mg of sodium per serving v. Low Sodium: less than or equal to 140mg of sodium per serving vi. Fat Free: less than .5g of fat per serving vii. Low Fat: up to 3g of fat per serving viii. “Reduced, Less, Fewer”: at least 25% less fat compared to reference food i. Health Claim: expressed or implied statement in food labeling about the relationship of a food substance to a disease or health condition II. Food Choices & Nutrition Standards a. Why Eat? i. Have to: physiological response (hunger) ii. Want to: psychosocial response – appetite, stress, habit, special occasions, social norms b. Physiological Response (Hunger) i. Hypothalamus 1. Regulates hunger by communicating between brain and body 2. Regulates the release and uptake of chemicals 3. “satiety” center of the brain 4. Processes nerve signals throughout the body c. What Causes Hunger? i. Hormones, Brain Chemicals 1. Ghrelin – from stomach, major hunger signal 2. Leptin – from adipose tissue (fat tissue), suppresses the desire to eat 3. Neuropeptide Y – comes from the hypothalamus, type of neurotransmitter that sends messages to the brain when the body needs nourishment 4. Our appetite is regulated by Ghrelin and Leptin d. Other Factors Affecting Hunger i. Composition of Meals ii. Food as a Reward iii. Food as a coping device or stress reliever iv. Appetite e. Random Knowledge i. 75% of the U.S. has a weight issue ii. 56g of sodium daily iii. Essential Nutrients – nutrients our body cannot produce on its own iv. 1 cup of Milk = 100 calories which contains 8g of protein f. Food Accessibility i. Food Desert: area with limited access to affordable and nutritious food, low income neighborhoods ii. Food Insecurity: inability of an individual or household to afford and or access a healthy diet g. What is a Nutrient? What is Nutrition? i. Nutrient: components of food used for the body’s functioning ii. Nutrition: the study of the nutrients in foods and in the body h. Classes of Nutrients i. Macronutrients 1. Proteins 2. Carbohydrates 3. Lipids ii. Micronutrients 1. Vitamins 2. Minerals 3. Water i. Kilocalorie (Kcal) – unit of energy (heat) i. Proteins (C, N, O, H, S) – 4kcal/g ii. Carbohydrates (C, H, O) – 4kcal/g iii. Fats – (C, H, O) – 9kcal/g iv. Alcohol – 7kcal/g v. Vitamins, Minerals, & Water do not provide energy j. Requirements for Nutrients i. Phytochemicals: beneficial nonnutrient chemical compounds that occur naturally in plants k. Nutrient Density i. Nutrient Content/Kcal Content = Nutrient Density ii. Nutrient Dense Foods: vegetables fruits, whole grains, low fat dairy, legumes and nuts iii. These foods are rich in vitamins, minerals and other beneficial substances iv. Low in calories, fat, & salt l. Calories i. Calorie: amount of heat energy (kcal) needed to raise the temperature of water by 1˚ C (measured by bomb calorimeter) ii. Food energy is measured in kilocalories m. Dietary Reference Intakes (DRI’s) – umbrella term for… i. RDA (Recommended Dietary Allowances) ii. EAR (Estimated Average Requirement) iii. AI (Adequate Intake) iv. Upper Limit n. Recommended Dietary Allowances (RDA’s) i. This is the average daily dietary nutrient intake sufficient to meet the nutrient requirements for 9798% of healthy individuals ii. There are different RDA’s for varying age & gender groups as well as pregnant women iii. To set the RDA 1. For energy set at the average amount needed by a group 2. For a nutrient estimate the average needed for a group and add 30 50% iv. RDA = recommendations, not requirements, consuming less than 2/3 or more than suggested may put a person in harm v. Recommendation – normalized estimate of nutrient to cover most individuals in a population group o. Estimated Average Requirement (EAR) i. Average daily nutrient intake estimated to meet the requirement of half the healthy individuals ii. Requirement – minimum amount of a nutrient to sustain a body’s physiological state, function or structure p. Adequate Intake i. Recommended average daily intake based on observed, experimentally determined estimates of nutrient intake by a group of healthy people ii. This is used when RDA cannot be determined q. Upper Intake i. Total intake from food & supplements should not exceed this amount r. 4 DRI Categories s. Dietary Guidelines for Americans i. Purpose – provide science based advice for ages 2 & up, along with those at risk of chronic disease ii. Target Audience – policy makers, nutrition educators, health professionals, general public iii. Created by the USDA & HHS, updated every 5 years iv. Guidelines for 2015 1. Follow healthy eating pattern (obviously?) 2. Focus on variety, nutrient density, & amount 3. Limit calories from added sugars, saturated fats and reduce sodium intake 4. Healthier food and beverage choices (redundant) v. Serving = unit of measure vi. Portion = amount of food actually served/consumed t. Healthy Eating Pattern Limits i. Consume less than 10% of calories per day from added sugars ii. Consume less than 10% calories per day from saturated fat iii. Consume less than 2300mg of sodium per day III. Nutrition & Physiology a. Body Organization i. Cells, Tissues, Organs, Systems, Organism (the Body) b. The Cell i. Nucleus – control center, contains DNA ii. Mitochondrion – “the power house of the cell” produces ATP iii. Glogi Complex – packaging center iv. Ribosome – protein synthesis v. Endoplasmic Reticulum – membranous channels 1. Smooth – cholesterol synthesis & fat metabolism 2. Rough – protein production vi. Plasma Membrane – regulates cell exit and entry vii. Lysosome – “the housekeeper” viii. Membrane Receptors – proteins that detect signals ix. Cytoplasm – fluid & organelles between nucleus and outer membrane x. Tissue – group of cells performing a specialized function 1. Ex. Connective tissue, Muscular tissue, Nerve tissue xi. Organ – group of tissues performing a specialized function c. Integumentary system i. Skin, hair, nails, sweat glands ii. Provides covering for the body and maintains body temperature iii. Excretes salts and urea in perspiration d. Skeletal System i. Bones, joints, ligaments, cartilage ii. Provides protection & support iii. Nutrients play major role in development and maintenance e. Muscular System i. Skeletal muscles, enable body movement ii. High energy & nutrient requirements depending on the activity f. Nervous System i. Brain, spinal cord, nerves, & sensory receptors ii. Sensation interpretation & integration iii. Food components can affect development and function g. Endocrine System i. Glands – pituitary, thyroid, adrenal, pancreas ii. Secrets hormones that help regulate body activities such as growth and reproduction iii. Numerous food components affect functioning h. Cardiovascular System i. Heart, blood, blood vessels ii. Transports nutrients and oxygen around the body iii. Diet can benefit or impair functions i. Lymphatic System i. Lymph vessels, lymph nodes, spleen, tonsils ii. Returns fluids to blood iii. Involved in lipid absorption iv. Concerned with defense against pathogens and foreign substances j. Respiratory System i. Longs and respiratory passages (pharynx, larynx, trachea, bronchi) ii. Takes in oxygen and excretes carbon dioxide iii. Nutrients affect ability to carry oxygen and protect mechanisms k. Digestive System i. Mouth, esophagus, stomach, intestines ii. Takes in, breaks down and absorbs food then excretes solid waste l. Urinary System i. Kidneys bladder, ducts ii. Excretes waste as urine and regulates body water and salt balance iii. Regulates acidbase balance of blood m. Reproductive System i. Gonads (aka testicles aka balls), vagina, genitals ii. Production of offspring n. Immune System i. Lymphocytes & Phagocytes ii. Produce antibodies, destroy invader cells and viruses iii. Enables the body to resist disease IV. The Digestive System a. Digestion: the breakdown of food components into small enough structures to facilitate absorption, both a mechanical and chemical process b. The Mouth i. Mechanical – chewing ii. Chemical – saliva from 3 pairs of salivary glands c. Saliva i. Moistens food making it easier to chew ii. Dissolves food chemicals allowing us to taste iii. Starch (amylase) small polysaccharides (oligosaccharides) iv. Amylase breaks down carbohydrates into sugars v. The salivary enzyme lipase begins the digestion of fat (triglycerides) vi. Triglycerides (lipase) fatty acids, mono & di glycerides vii. Lipase breaks down lipids d. The Esophagus i. Mechanical – peristaltic movement: the contraction of muscles pushes food down, occurs throughout most of the body, allows us to swallow while upside down ii. Chemical – none e. The Digestive System i. Esophagus – tube of smooth muscle (no chemical secretions) ii. Liver – produces bile, stored and concentrated in the gallbladder iii. Stomach – produces HCI (hydrochloric acid) and pepsin (proteolytic enzyme) which breaks down proteins into peptides and amino acids iv. Secretions produced in the pancreas, intestine and liver are active in the small intestine to break down carbohydrates, fats, and proteins v. Colon – reabsorbs water and minerals vi. Rectum and Anus – stores and regulates elimination of feces f. The Stomach i. Stomach acid uncoils protein strands and activates stomach enzymes ii. Pepsin = proteolytic enzyme used for protein lysing iii. The stomach’s mechanical process includes grinding and churning of food with secretion converts food into a liquid mass iv. salivary amylase is inactivated by stomach acid while salivary lipase is active at an acid pH g. Carbohydrates i. The pancreas produces an amylase that is released through the pancreatic duct into the small intestine ii. Polysaccharides (pancreatic amylase) small polysaccharides iii. Bile = emulsifier, bile attacks and breaks down fat iv. Small intestinal cells secrete enzymes to further hydrolyze the polysaccharides into monosaccharides and the cells absorb them 1. Maltose (maltase) Glucose + Glucose 2. Sucrose (sucrose) Fructose + Glucose 3. Lactose (lactase) Galactose + Glucose h. Fats i. Bile produced in liver, flows in from the gallbladder (via the common bile duct) ii. Fat (bile) emulsified fat (fat mixed with water) iii. Pancreatic lipase flows in from the pancreas iv. Emulsified Fat (pancreatic lipase) monoglycerides, glycerol, fatty acids (absorbed) i. Proteins i. Pancreatic and small intestinal enzymes split polypeptides further ii. Polypeptides (pancreatic & intestinal proteases) dipeptides, tripeptides iii. Enzymes on the surface of the small intestinal cells hydrolyze these peptides and the cells absorb them iv. Peptides (intestinal dipeptidase and tripeptidase) amino acids j. Small Intestine Structure i. Has many folds, contain finger like projections called villi which are covered in microvilli ii. Microvilli produce enzymes iii. Between folds are glands that secret mucus iv. Capillaries and lymph vessels in villi v. Lymph vessels carry lipid materials k. Large Intestine i. Bacterial enzymes digest fiber ii. Fiber (bacterial enzymes) fatty acids & gas iii. Fiber holds water, regulates bowel activity, binds cholesterol and come materials carrying them out of the body l. Chemical Digestion i. Sugar and starch (carbohydrates) – yield glucose, fructose, galactose ii. Fats (lipids) – yield fatty acids, monoglycerides and free cholesterol iii. Protein – yields amino acids iv. Fiber – binds cholesterol and some minerals, yields some volatile fatty acids m. Absorption of Digestion Products i. Fats – small fatty acids enter blood, larger fatty acids enter lymphatic system ii. Carbohydrates – glucose, fructose and galactose enter bloodstream iii. Proteins – amino acids enter bloodstream n. Excretory Products i. Feces – fiber and undigested food, microflora, bile products ii. Urine – urea, electrolytes (potassium and sodium), bicarbonate, ammonia V. Carbohydrates a. Functions – main energy source for cells, spare proteins, add bulk to foods, provide fiber b. Sources – grains, fruits, dairy c. Types i. Simple Carbohydrates: sugar, monosaccharides, molecule with 6 carbons, oxygen and hydrogen ii. Complex Carbohydrates: starches and fiber, sometimes called poly saccharides, long chains of sugar units d. Monosaccharides: 6 carbon molecules i. Glucose – body’s main fuel ii. Fructose – fruit sugar iii. Galactose – 1 of 2 components of the milk sugar lactose e. Disaccharides i. Sucrose – Glucose + Fructose ii. Lactose – Glucose + Galactose iii. Maltose – Glucose + Glucose f. Polysaccharide (3 Types) i. Glycogen – animal starch, long chains of glucose molecules ii. Starch – from plant sources iii. Fiber – plant material, long chains of glucose molecules whose structure is resistant to enzymatic degradation 1. Types: cellulose, hemicellulose & pectin g. How Carbohydrates in Food become Glucose 1. Fiber, starch & sugars enter small intestine (pancreatic amylase breaks down starch to disaccharides) 2. Enzymes on small intestine wall break down “di” to “mono” saccharides 3. Monosaccharides enter capillary (go to liver) 4. Liver converts galactose & fructose to glucose 5. Fiber travels through unchanged into the colon h. Lactose Intolerance i. Deficiency in the enzyme lactase ii. Symptoms: nausea, diarrhea, gas iii. Affects 80% of world pop. iv. Lactase, which breaks down lactose, is not present to perform function i. Regulation of Blood Glucose i. After a meal blood glucose rises which promotes an increase in insulin release from ß cells of pancreas ii. Insulin promotes glycogen formation in liver and muscle iii. After a while glucose levels fall promoting glucagon release, glucagon stimulates glycogen conversion to glucose in liver j. Glucose Metabolism i. Glucose enters the cell, divided into 2 3 carbon fragments (pyruvate) and energy (ATP) 1. Pyruvate enters the mitochondrion and is reduced to 2carbon units (acetylcoA) ii. This process is done anaerobically, yields CO2 as well as 2 ATP’s iii. acetylcoA enters the Krebs Cycle and electron transport train, creates 32 ATP’s, CO2 and water k. Glycogen Metabolism i. 1/3 of all glycogen is stored in the liver, the other 2/3 is stored in muscles ii. Glucagon breaks down liver glycogen to glucose (then enters blood) iii. Epinephrine – breaks down muscle glycogen to glucose (used to produce ATP for muscles) l. Nutrient Conversion to Fat i. Excess carbs are converted to fat in the liver after filling glycogen levels and restoring normal blood glucose ii. Excess protein and fat can result in fat deposition iii. The liver releases these fatty acids into the blood iv. Fat cells aka adipocytes take fatty acids and store them m. Lack of Carbohydrates can Leady to 2 Problems: 1. Fat cannot be broken down properly for energy without carbohydrates so the body converts fat into ketone bodies 2. Ketosis: occurs when a high concentration of ketone bodies accumulate in the blood (minimum of 130g) n. Diabetes i. Type 1 – IDDM 1. Characterized by an immune response to pancreatic ß cell 2. Eventually the pancreas stops making insulin 3. Occurs early in life ii. Type 2 – NIDDM 1. Characterized by insulin resistance, the insulin is there but it does not work to induce glucose uptake by cells 2. Occurs later in life iii. Blood Glucose Values 1. Normal: 100 mg/dL 2. Prediabetes: 100125 mg/dL 3. Diabetes: 125 mg/dL iv. Results of Diabetes – blindness, nerve damage, amputation, kidney and heart disease, increased infections v. Alternative Sweeteners 1. Corn Syrup (high fructose), molasses, laevulose (fructose), honey, sugar alcohols VI. Lipids a. Functions i. Insulates and protects organs ii. Source of essential fatty acids iii. Source of calories (9 kcal/g) b. Types of Lipids i. Triglycerides ii. Phospholipids iii. Sterols c. Triglycerides – main form of fat in food, composed of glycerol and 3 fatty acids i. Fatty acids are classified by: length, location of double bonds, number of carbon atoms, organization of hydrogen around double bonds d. Phospholipids i. Glycerol + 2 fatty acids + phosphorus ii. Phosphorus makes the phospholipid water soluble iii. Fatty acid makes it soluble in fat iv. Meaning phospholipid can serve as an emulsifier e. Sterol i. Large molecule of interconnected rings of carbon with side chains of carbon, hydrogen and oxygen atoms attached ii. Cholesterol – found in all animal cell membranes, nonessential and forms plaques that can cause atherosclerosis iii. Cholesterol serves as the raw material for bile, Vitamin D, steroid and sex hormones f. Saturated Fatty Acid: a fatty acid carrying the maximum number of hydrogen atoms g. Unsaturated Fatty Acid: a fatty acid with less than maximum hydrogen atoms i. Monosatruated and polysaturated fatty acids h. Trans Fatty Acids: fatty acids with unusual shapes, arise when polysaturated oils are hydrogenated i. Advantage: controls consistency and oxidation of fats ii. Disadvantage: increases LDL (low density lipoproteins) iii. Found in margarines, shortenings and baked goods i. Essential Fatty Acids i. Abundant in fish oils ii. Lower blood pressure iii. Prevents blood clot formation iv. Protects against irregular heartbeats v. May reduce inflammation, supports immune system and may inhibit cancers vi. Essential for normal infant growth and development j. Omega 3 Fatty Acids i. Linolenic Acid ii. Docosahexaenoic Acid (DHA) iii. Eicosapentaenoic Acid (EPA) iv. Sources – fatty fish (salmon, tuna herring), flaxseed, canola, soybean oils, almonds, walnuts, spinach k. Omega 6 Fatty Acids i. Linoleic Acid ii. Precursors of Omega 6 Eicosanoids iii. Sources – grains, fats and oils l. Eicosanoids i. Hormonelike compound made from EFA’s and act through receptors on tissues to regulate many body responses ii. Omega 6 causes inflammation, blood clotting and tumor growth (BAD) iii. Omega 3 reduces inflammation, blood clotting and tumor growth (GOOD) m. Imbalance of Omega 6 & Omega 3 i. Too much of one interferes with the other ii. Recommended ratio of Omega 6:3 from 5:1 to 10:1 iii. American diet is too low on Omega 3 iv. Average U.S. intake 150 mg/day v. Recommended is 500 mg/day to reduce cardio vascular disease n. Fish Oil Supplements i. May raise LDL ii. High intake may increase bleeding times iii. May interfere with wound healing iv. May suppress immune function v. May upset Omega 3 & 6 balance o. Fish & Mercury i. Fish contaminated with mercury is considered still safe to eat ii. Best for consumption of 2 3 ounce servings of ocean fish per week iii. Benefits outweigh risks iv. Salmon generally high in Omega 3 and low in mercury p. Digestion & Absorption i. Depends on: preduodenal lipase (gastric), pancreatic lipase & bile acids for emulsification ii. Lipase breaks down triglycerides into free fatty acids and monoglycerides iii. Short chain fatty acids are absorbed through the portal vein (blood to liver) during lipid digestion iv. Long fatty acids & monoglycerides get repackaged as triglycerides for transport in chylomicrons (largest lipoprotein) v. Enters lymph (fluid of lymphatic system) and then the bloodstream q. Lipoprotein Transport Types i. Chylomicrons – from intestine to body (large) ii. VLDLs – Very Low Density Lipoproteins (liver) iii. LDLs – Low Density Lipoprotein (liver) 1. VLDLs & LDLs take triglycerides and cholesterol to the body iv. HDLs – High Density Lipoproteins (liver, smallest) 1. Scavengers for cholesterol, brings it back to the liver r. Lipoprotein Profile i. LDLs associated with increased risk of Heart Disease ii. HDLs associated with decreased risk of Heart Disease iii. Lower LDL by: 1. Lower saturated and trans fat 2. Substitute mono & poly unsaturated for saturated 3. Lower cholesterol intake iv. Raise HDL 1. Exercise 2. Decrease trans fats 3. Red Wine s. Fat Replacers i. Olestra – a noncaloric artificial fat made from sucrose and fatty acids (aka sucrose polyester) 1. Indigestible and can have laxative effects in excess ii. Simplesse – protein based, low calorie artificial fat, FDA approved for use in foods
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