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This 6 page Class Notes was uploaded by Emma Trokel on Monday February 22, 2016. The Class Notes belongs to 2420-001 at University of Colorado at Boulder taught by S. Nelson in Spring 2016. Since its upload, it has received 12 views. For similar materials see Nutrition and Health Performance in Psychlogy at University of Colorado at Boulder.
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Date Created: 02/22/16
Week 6 Chapter 8 Vitamins Vitamins: Basic Concepts ● What is a vitamin? ○ A complex organic compound that: ■ Is not made by the body or made in amounts that are enough to maintain a good health ■ Occurs naturally in common foods ■ Causes a deficiency disorder when it is missing from the diet ■ Restores good health, if the deficiency disorder is treated early by supplying the missing substance Sources of Vitamins ● Natural Sources: ○ Plants, animals, fungi, and bacteria ● Synthetic: ○ Made in laboratories by chemists synthesized by microbes in laboratories ● Most natural and synthetic forms have equal activity in the body except: ○ Natural vitamin E: greater activity than synthetic ○ Synthetic folic acid: greater activity than natural Classifying Vitamins ● Fat soluble A, D,E, & K ○ associated with lipids in foods and the body ■ do not dissolve in water or urine ● Stored in the body and may be toxic ● Water soluble B vitamins and C ○ Dissolve in watery components of foods and the body ■ excreted in urine ■ most are not stored to a major extent ● generally non toxic Roles Of Vitamins Vitamins may: have hormonal action (e.g. vitamin D) participate in certain chemical reactions regulate a variety of body processes cell division growth and maintenance of tissues Vitamin Absorption ● Most absorption occurs in small intestine ○ absorption is not 100% efficient ● Absorption generally increases when more of the vitamin is needed: ○ Growth (during infancy and adolescence) ○ Pregnancy ○ Lactation (milk production) Populations at Risk for Vitamin Deficiency ● Alcoholics ● Older adults ● hospitalized people (long term) ● People with: ○ Anorexia nervosa ○ Certain gastrointestinal disorders ○ Rare metabolic conditions Vitamin A ● Retinol (preformed A): ○ most active form; in animal foods ● Betacarotene (provitamin A) ○ Carotenoid that the body can convert to some retinol ● Major Functions: ○ Normal vision and reproduction ○ cellular growth ○ Immune system activity ○ Epithelial cell production and maintenance What is Night Blindness? ● The inability to see in dim light ● Early sign of vitamin A deficiency ○ the retina, the lightsensitive area inside each eye, contains rods and cones that are specialized nerve cells essential for vision ■ rods and cones need vitamin A to function properly Vitamin A Adequacy and Deficiency ● Dietary Adequacy: ○ RDA: 700 900 mcg RAE ● Vitamin A Deficiency: ○ certain epithelial cells produce too much keratin ■ Keratin tough protein found in hair, nails, and outermost layers of skin ○ Excess Keratin: ■ Skin becomes rough and bumpy ■ Inner eyelid cells that normally secrete mucus to protect cornea become keratinized ● can result in xerophthalmia Vitamin A Toxicity ● Excess vitamin A (retinol) may lead to liver damage ● Excess betacarotene (carotenemia): ○ yellowing of skin due to excessive betacarotene intake ■ generally harmless ■ Accutane Vitamin D ● Rickets: vitamin D deficiency in children ○ results in soft bones that do not grow properly and become deformed Why is Vitamin D Necessary? ● Vitamin D is needed for: ○ Metabolism of calcium and phosphorus ○ Production and maintenance of healthy bones ● Parathyroid hormone (PTH): ○ Released when blood calcium levels drop ○ Stimulates kidneys to increase active vitamin D produces and decreases urinary calcium excretion Vitamin D Adequacy and Deficiency ● Dietary Adequacy: ○ RDA: 15 mcg/day for adults < 70 years of age ● Vitamin D deficiency: ○ Rickets ■ Uncommon ■ May develop in breastfed infants ○ Osteomalacia “adult rickets” Vitamin D Toxicity ● Upper limit (UL): ○ 100 mcg/day (4000 IU) ● Vitamin D toxicity: ○ Too much calcium is absorbed ■ The excess calcium is deposited in soft tissues including kidneys, heart, and blood vessels Vitamin E ● Alphatocopherol ● Functions: ○ fatsoluble antioxidant found in cells ■ protects polyunsaturated fatty acids (good) ● maintains immune system function Vitamin E Adequacy, Deficiency, and Toxicity ● Dietary Adequacy ○ RDA: 15 mg/day ● Vitamin E Deficiency ○ Impaired immune system function ○ Nerve damage ● Vitamin E Toxicity ○ Upper limit (UL) 1000 mg/day ○ Excess may interfere with vitamin K’s role in blood clotting How do Antioxidants work? ● By giving up an electron to a free radical, an antioxidant protects other molecules. ○ Action stabilizes the free radical ● Betacarotene and vitamins E & C function as antioxidants antioxidants protect phospholipids, DNA, unsaturated fatty acid, proteins from free radicals Vitamin K ● Liver needs vitamin K to make certain clotting factors Vitamin K Adequacy, Deficiency, and Toxicity ● Dietary Adequacy: ○ Al: 120 mcg/d for men; 90 mcg/d for women ● Vitamin K Deficiency: ○ May occur in newborns or ○ on long term antibiotic therapy ● Vitamin K Toxicity: ○ None known for natural forms ○ synthetic forms are toxic ● produces vitamin K in the bacteria in our intestines Thiamin ● Functions: ○ Part of coenzyme involved in release of energy from carbohydrates ○ Metabolism of certain amino acids ○ Synthesis of neurotransmitters Vitamins do not have calories / give energy Thiamin Deficiencies ● Beriberi: ○ People are weak, have poor muscular coordination, and may develop cardiovascular problems and edema. Note severe pitting edema (fancy way of saying swelling) in woman’s left leg. ● WernickeKorsakoff syndrome: ○ Typically seen in alcoholics, because alcohol decreases absorption and increases excretion. Riboflavin ● Functions: ○ Coenzyme for metabolism of carbohydrate, lipids, and amino acids ● Deficiency: ○ May occur in people who do not drink milk or eat enriched grains ★ Because B vitamins are water soluble they are often added in grains Niacin ● Functions: ○ Part of two coenzymes that participate in at least 200 reactions ● Deficiency: ○ Pellagra: the “4 D’s” of pellagra Dermatitis, Diarrhea, Dementia, Death Folate ● Folic acid (synthetic) and Folacin ● Functions: ○ Good Food Sources of Folate: ■ Leafy green vegetables, liver, legumes, asparagus, broccoli, and oranges ● A B vitamin Neural Tube Defects ● During the first few weeks after conception, the neural tube forms ○ Neural tube develops into the brain and spinal cord ● Folatedeficient pregnant women are at risk if giving birth to infants with neural tube defects ● Anencephaly ○ Brain does not form properly ● Spina bifida ○ Spine does not form properly before birth and fails to enclose the spinal cord Vitamin C ● Functions not part of coenzyme: ○ Collagen synthesis ■ protein that gives strength to connective tissues ■ collagen makes up your tendons ○ Antioxidant activity ○ Other roles: ■ Immune system functioning ■ Synthesis of bile, and certain neurotransmitters and hormones ● Dietary Adequacy: ■ RDA = 75 to 90 mg/day (smokers have higher RDA’s)
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