Exam 3 Study Guide
Exam 3 Study Guide NTRI 2000-002
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This 14 page Study Guide was uploaded by Kaylen Taylor on Thursday April 7, 2016. The Study Guide belongs to NTRI 2000-002 at Auburn University taught by Michael Winand Greene in Fall 2015. Since its upload, it has received 117 views. For similar materials see Nutrition and Health in Nutrition and Food Sciences at Auburn University.
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Date Created: 04/07/16
Amino acids: building blocks of protein o Amino: “nitrogen containing” o Structure Carbon atom Amino group o All proteins are made up of 20 different amino acids o Different amino acids have different side chains o 9 essential amino acids: must be taken through diet o Sometimes non-essential amino acids become essential ex. Tyrosine o Breakdown of amino acids leave behind ammonia. The ammonia is turned into urea in the liver and then excreted by the kidneys during urination. o Protein structure Primary structure: sequence of amino acids Secondary structure: interaction between close amino acids Tertiary structure: interaction between far away aminoacids Protein organization Order of amino acids in protein determines its ultimateshape Proteins final shape determines its function in the body Dietary protein High quality: animal protein, except gelatin o Also called complete proteins (all 9 essential amino acids) Low quality: plant protein, except soybeans o Also called incomplete proteins o Lacks one more essential amino o Will need variety of low-quality protein foods to get allessential amino acid or protein synthesis will stop Limiting amino acid All or none principle in protein synthesis o Either all essential amino acid are available or none canbe used Limiting amino acid o An essential amino acid in short supply Complementary proteins o 2 or more proteins combine to compensate for deficiencies Proteins: Functions Producing vital structures o Muscles, connective tissue, enzymes, hormones, antibodies Building blocks of body components Forming glucose (during fast, starvation) Contribute acid-based balance Provide energy (4 kcals/g) Provides highest feeling of satiety after meal Maintaining fluid balance (Edema) Protein RDA o 0.8 grams/kg of healthy body weight 154/2.2 = 70 kg 70 kg *0.8 = 56 grams So about 10% of total calories. o Food and Nutrition Board sets upper range at 35% o In the U.S., typical protein intake is about 100 grams for men and 65 grams for women. The typical protein intake is greater than what is needed. Protein deficiency: kwashiorkor Protein calorie malnutrition: kwashiorkor Ghana word meaning “disease first child gets when the new child comes” Young children 1-3 years old Develops after weaning (from milk to starchy roots andgruels) Severe protein deficit, moderatecalorie deficit Develops quickly Edema, fatty liver Protein calorie malnutrition: marasmus Greek word meaning “to waste away” Starving to death Inadequate intake of calories, protein, and other nutrients Vitamins Vitamin A deficiency: xerophthalmia Vitamin D deficiency: bowed legs of rickets Fun Facts Named in order of discovery Substances found not to be essential were dropped (vitamin P) B-vitamins were thought to be one vitamin; turned outto be many Get your vitamin from the sun (vitamin D) Gut bacteria makes vitamin K and biotin Vitamins as drugs o NIACIN (for lipid lowering) o Megadose (>3-10x higher dose) Most synthesized vitamins work equally well in the body o Vitamin E is an exception o Interestingly synthetic folic acid is 1.7x more potent than natural form Vitamins Essential organic substances needed in small amounts in the diet for normal function, growth, and maintenance of the body Produce deficiency symptoms when missing from diet Yield no energy (no kcals) Vitamin Classification Fat-soluble vitamins o A, D, E, K o Not really excreted (except vitamin K) Water-soluble vitamins o B, C o Generally lost from the body (except vitamins B-6 and B-12) o Excreted via urine Vitamin Toxicity Fat-soluble vitamins o Can accumulate in the body Water-soluble vitamins o Some can cause toxicity (15-100x more) Toxicity mostly due to supplementation Vitamins Functions o Facilitate energy yielding chemical reactions o Function as co-enzymes Combine with inactive enzyme to form andactive enzyme Vitamin B, and K Preservation of Vitamins Vitamin content decreases with: o Improper storage o Excessive cooking o Exposure to light, heat, air, water, and alkalinity Eat foods soon after harvest, do not freeze Frozen veggies and fruits retain most vitamins as freshly picked ones Blanching destroys enzymes that breakdown vitamins, slowing down vitamin degradation FatSoluble Vitamins Dissolve in organic solvents Not readily excreted; can cause toxicity Absorbed along with fat Fat malabsorption may result in vitamin deficiency o Cystic fibrosis o Ex: orlistat – weight loss drug Transported with fat, through lipoproteins VitaminA Deficiency and toxicity can cause defects Narrow optimal intake range Retinoids or preformed vitamin A o Only found in animal products Provitamin A (inactive vitamin A) o Can be converted to Vitamin A o Carotenoids (beta carotene, lutein, zeaxanthin) o Found in plant products Functions of Vitamin A Promotes vision o Night blindness, light-dark vision (adjust from bright to dim light) Prevents drying of the skin and eyes o Cornea of the eye lose their ability to produce mucus –Xerophthalmia (dry eye) Macular degeneration (blurred vision): adults over 65 years (legal blindness) Carotenoids – beta carotene, lutein, zeaxanthin o Centrum silver – good source of lutein General Cell Health o Vitamin a maintains the epithelial cells. Epithelial cells serve as an important barrier to bacterial infection. Promote immune function and resistance to bacterial infection o Promotes growth by binding receptors on DNA and increase the protein synthesis Cardiovascular disease prevention o Carotenoids antioxidant property – 5 servings of fruitsand veggies Cancer prevention o Antioxidant property, carotenoid rich food reduce lung and oral cancer, dietary carotenoid found in tomatoes (lycopene) – decrease skin cancer and prostate cancer Recommended Amounts for vitamin a 700-900 microgram RAE Daily value is 1000 microgram or 5000 IU Upper lever is 3000 mcg or 10,000 IU Much is stored in the liver Toxicity of Vitamin A Large intake of vitamin A (preformed) o Over a long period o Acne medications: Accutane and Retin-A o Birth defects: fetal malformation, spontaneous abortion High carotenoid intake: no toxic effects VitaminD Derived from cholesterol Synthesized from exposure to sun o 80-100% of needs met o Expose hands, face, arms 2-3x per week for 5-10 minutes each time (more for darker skin) o Insufficient sun exposure make this a vitamin o Sunscreen SPF >_ 8 decreases synthesis 95% Prohormone (means inactive hormone) Liver and kidney enzymes convert prohormone to active hormone Active vitamin D acts on bone cells and intestinal cells Activation of Vitamin D Sun skin liver kidney Functions of Vitamin D Regulates blood calcium o Along with the parathyroid hormone o Regulates calcium and phosphorus absorption o Regulates calcium deposition in bones Influences normal cell development o Linked to reduction of breast, colon, and prostate cancer Role in bone formation Increased calcium and phosphorus deposition in bones o Strengthens bones Rickets o Breastfed infants with little sun exposure o Early 20 century, very common deficiency Osteomalacia (means soft bones) o Rickets-like disease in adults o Bone loses minerals and becomes porous o Hip and bone fractures Adequate intake for vitamin d 5 mcg/d (200 IU/day) for adults under age 50 10-15 ug/d (400-600 IU/day) for older adults Concern for vegans in colder climates Toxicity Warning No toxicity from sun exposure Supplementation can be toxic, especially in infancy andchildhood Upper level is 50 mcg/day Toxicity can result in o High calcium in blood (hypercalcemia) o Calcium deposits in organs and blood vessels Vitamin K(“koagulation”) Acts as coenzyme, activating blood clotting factors o Role in coagulation process Synthesized by bacteria in the colon and absorbed (meets 10% requirements) Role in calcium-binding: low vitamin k intake related to hip fractures Vitamin K – NOT stored efficiently in the body Adequate intake for vitamin k 90-120 mcg/day (DV: 80 mcg/d) Newborns o Routinely injected with vitamin k o Breast milk is a poor source, lack intestinal bacterial Deficiency leads to increased bleeding, internal hemorrhage Toxicity unlikely; readily excreted (no upper limit) The mighty antioxidants: vitamin E and C Antioxidants Antioxidant: a chemical that prevents the oxidation of other chemicals In biological systems, the normal processes of oxidation produce highly reactive free radicals o These can readily react with and damage other molecules Vitamins E and C, carotenoids, mineral selenium, herbs- phytochemicals Vitamin E Fat soluble vitamin in cell membranes Protects double bonds in unsaturated fats Protective role in cardiovascular health o Not enough research to make healthclaim Improves vitamin a absorption Deficiency o Breakdown of cell membranes o Hemolysis: RBC membrane damage RDA for adults is 15 mg/day or 22 IU (DV: 30IU) o Many adults are not meeting thisgoal Food sources of Vitamin E o Vegetable oils o Nuts, seeds, soybeans o Animal fats and fish oil have NO vitamin E Susceptible Populations o Preterm infants o Smokers o Very-low fat diets or fat malabsorption Toxicity o Upper level is 1000 mg/day (supplementary) o Upper level is 1500 IU (natural) or 1100 IU (synthetic) o Toxic effects Interfere with vitamin K’s role in clotting mechanism (anticoagulants, aspirin) Possible hemorrhage Muscle weakness, headaches, nausea Overview of Water-Soluble Vitamins Subject to cooking losses General readily excreted from the body Function as coenzymes Participate in energy metabolism Marginal deficiency more common B-vitamins 8 B vitamins Thiamin, riboflavin, niacin, pantothenic acid, vitamin B6, biotin, folate, and vitamin B12 VitaminC Deficiency: scurvy o Deficient for 20-40 days o Fatigue, pinpoint hemorrhages o Bleeding gums o Weakness o Fractures Not synthesized by humans Decreased absorption with high intakes Excess excreted o Diarrhea common Functions of vitamin C o Synthesis of collagen Found in bone, teeth, tendons Important in wound healing o Iron absorption o Immune functions, reduce colds? o Antioxidant and free radical scavenger Prevent certain cancer and cataract of the eye RDA: 75-90 mg/day Upper Level is 2 g/day Thiamin (vitaminB1) Deficiency: Beriberi (weakness, loss of appetite, nervous tingling, calf-muscle pain) o Risk: alcoholism, anorexia Coenzyme form used in breakdown of carbohydrates for energy needs White rice vs. brown rice RDA o 1.1-1.2 mg/day o Most exceed RDA in diet Surplus is rapidly lost in urine; non-toxic (no upper level) Riboflavin (VitaminB2) Coenzyme forms participate in the breakdown of carbohydrates and fats yielding energy Deficiency o Cheilosis, inflammation of mouth and tongue, dermatitis, sensitivity to sun o Occurs with deficiency of thiamin, niacin, and B6 RDA o 1.1-1.3 mg/day o Average intake above RDA Nontoxic Niacin (VitaminB3) In the body niacin exists as nicotinic acid and nicotinamide Coenzyme used in synthetic pathways (fatty acid synthesis) Deficiency o Pellagra Symptoms: 3 D’s dermatitis, diarrhea, and dementia RDA o 14-16 mg/day Toxicity o Upper level is 35 mg/day o Niacin megadose: 1-2 g/day for lowering LDL cholesterol and triglycerides, and raising HDL cholesterol o Side-effect: flushing (increased blood flow to the skin, itching, burning) VitaminB6 A family of 3 compounds: pyridoxine, pyridoxal, and pyridoxamine B6 involved in carb, protein, and fat metabolism o Maintains blood glucose levels Aids in releasing glucose from glycogen sores o Synthesis of nonessential amino acids o Synthesis of neurotransmitters o Synthesis of hemoglobin o Decreases homocysteine levels Elevated homocysteine is a risk factor for heart disease RDA o 1.3-1.7 mg/day o DV is set at 2 mg o Athletes may need more! Glycogen, protein metabolism o Vitamin B6 requirements increased with alcoholism B6 as a medicine? o 50-100 mg/day therapy Questionable treatment of premenstrual syndrome o Treatment of carpal tunnel syndrome o Pregnancy morning sickness o Toxicity potential >2 g/day can lead to irreversible nerve damage o Upper level set at 100 mg/day Folate (vitamin B9) Coenzyme o DNA synthesis o Homocysteine metabolism o Neurotransmitter formation Sensitive to: heat, oxidation, ultraviolet light Deficiency o Decreased red bloodcell synthesis o Megaloblastic anemia Anemia characterized by presence of abnormal large immature RBCs Inability to divide normally Decreased oxygen carrying capacity Also called macrocytic anemia o Neural tube defects (spina bifida and anencephaly) o In 1998, FDA mandates fortification of grain products with folate o Neural tube closes in 28 days of pregnancy RDA for Folate o 100 mcg/day for o 600 mcg/day for pregnant women o Excess intake can mask vitamin B12 deficiency o Upper level 1 mg (synthetic form) VitaminB12 Synthesized by bacteria and fungi Coenzyme o Maintenance of the myelin sheath that coats nerve cells o RBC formation Vitamin B12 absorption: requires “intrinsic factor” (made by stomach) for absorption Deficiency o Pernicious anemia Pernicious mean leading to death Anemia similar to folate-deficiency o Nerve degeneration and paralysis Food sources o Organ meats (liver, kidneys, heart) o Stored primarily in liver of animals o Animal products o Fortified milk RDA o 2.4 mcg/day for adults Over age 50, supplements suggested o Vegans require supplements of fortified milk o Non-toxic People who most likely need vitamin supplements Women of child bearing age (folic acid) Women who are pregnant (folic acid) Strict vegans (B12) Newborns (vitamin K) People with limited milk intake and sunlight exposure (vitamin D) Adults over age 50 (vitamin B12) Functions of Water o Solvent for chemical reactions within the body o Helps regulate temperature with sweat o Helps remove waste products Waste products dissolves into water o Cushions and lubricates Knees, joints, saliva, bile Water Deficiency o 1-2% water loss - Thirst mechanism occurs o How do we conserve water? Antidiuretic Hormone (ADH) Released by the pituitary gland Communicates with the kidney to conserve water. Aldosterone Released from the adrenal gland when blood volume decreases. Communicates with kidneys to conserve water and salt. o When Thirst is Ignored: 4% water loss - Muscles lose strength and endurance 10-12% water loss - Heat tolerance is decreased Become nauseous, confused, dizzy 20% water loss - A coma and perhaps death. OverConsumption of Water o Too much in a short period of time leads to water intoxication or poison o Dilutes sodium levels - Hyponatremia Symptoms: Nausea Confusion Vomiting Headaches Muscle Weakness Convulsions Minerals o Major minerals: > 100 mg a day o Trace minerals: < 100 mg a day o Bioavailability: How much we take in Mineral binders: o Oxalates: Found in spinach; binds calcium o Phytates: Found in grains; binds calcium, iron, zinc, others. o Mineral-Mineral Interactions: Calcium-Iron; Zinc-Copper o Vitamin-Mineral Interactions: Vitamin C: Improves iron absorption Vitamin D: Improves calcium absorption Calcium o Most abundant mineral in the body. o 99% of the calcium in the body is in the bones. Integral role in the bone structure. Storehouse for calcium in the blood. o Serum Calcium Functions: Regulates transport of ions across the cell membrane Also important in nerve transmission Helps maintain blood pressure Essential for muscle contractions Essential for secretion of hormones, enzymes, neurotransmitters, etc. Essential for blood clotting o Possible Health Benefits/Risks: Certaincancers and kidney stones Hypertension, high cholesterol, obesity o Osteoporosis: Decreased bone mass related to aging, genetic background, and poor diet. Sodium o Absorb about 100% of sodium consumed o 30-40% found in the bones o The major positive ion found in the extracellular fluid o Functions: Fluid balance between compartments Nerve impulse conduction Absorption of glucose o Deficiency: Excessive perspiration Vomiting Diarrhea Leads to muscle cramps, nausea, dizziness, coma Chloride o An ion of chlorine o Major negative ion for extracellular fluid o Used in producing stomach acids (HCl) and during immune response of white bloodcells. Potassium o Major positive ion in intracellular fluid compartment. 95% of body's potassium o Important in fluid balance and nerve impulse transmission o Increasing Potassium is associated with lower blood pressure. o AI: 4700 mg per day Iron o In every cell of the body o Absorb about 18% of that present in food. o Most iron associated with hemoglobin (RBC) and myoglobin (Muscle) o When RBC dies, iron is recycled. We lose very little, except during bleeding o Heme-iron is more readily absorbed than non-heme iron. o Vitamin C (75 mg) - enhances absorption of non-heme iron o Iron Deficiency Anemia: Decreased oxygen-carrying capacity of the blood. Lower number of RBC Less oxygen to the cells Affects 30% of the world population 1/2 of which is due to low iron Neurological dysfunction called Pica Low iron associated anemia o Iron toxicity Hemochromatosis: A genetic condition characterized with bronzing of the skin. Associated with an increase of iron absorption. UL: 45 mg a day Stomach irritation, toxicity can be life-threatening. Zinc o About 40% of dietary zinc is absorbed. o Zinc is a cofactor for up to 200 different enzymes o Functions: Growth Wound healing Sexual maturity Taste perception Immune system, indirect antioxidant o Zinc Deficiency Acne like rash Diarrhea Lack of appetite Delayed wound healing Impaired immunity Reduced sense of taste and smell Hair loss o Getting Enough Zinc RDA for men is 11 mg, women is 8 mg. UL: 40 mg Excess interferes with copper metabolism Toxicity can occur from supplementation or over consumption of zinc- fortified foods. Intake greater than 100 mg results in diarrhea, cramps,nausea, vomiting, etc. Selenium o Indirect antioxidant, works with vitamin E to help protect cell membranes from oxidizing agents. o Binds to enzymes to protect against oxidation. o May have anticancer properties. o Selenium Deficiency o RDA: 55 micrograms/day o UL: 400 micrograms/day (hair loss) Iodide o Ion of iodine o Used in the production thyroid hormone o Thyroid hormone helps regulate metabolic rate, and promotes growth and development. o Iodide Deficiency Cells of the thyroid enlarge in attempt to trap more iodine. Called Goiter. People are sluggish and gain weight. During pregnancy, deficiency cancause extreme and irreversible mental and physical retardation of developing baby. Can be reversed within the first six months of pregnancy o RDA & DV: 150 micrograms o Too much Iodide: UL: 1.1 mg High amounts can inhibit thyroid hormone synthesis. Copper o 12-75% of copper in the diet is absorbed. o Involved in the metabolism of iron by functioning in the formation of hemoglobin and transport iron. o Also involved in the formation of connective tissue. o Is a cofactor for antioxidant enzymes. o Getting Enough Copper: Absorption is highly variable. Higher intakes associated with lower absorption efficiency. Phytates, fiber, excess zinc and iron supplements interfere with absorption. AI: 1 mg for women, 1.6 mg for men. 10 mg can cause toxicity. Symptoms include GI distress, vomiting blood, tarry feces, damage to liver and kidneys. Toxicity only occurs with supplementation.
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