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Chapter 7

Chapter 7. Vitamins. Key Concepts. Noncaloric Essential nutrients necessary for many metabolic tasks and the prevention of certain diseases Organic substances Needed by body for normal metabolism, growth & maintenance. Key Concepts. Vitamins do not provide energy

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Chapter 7

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  1. Chapter 7 Vitamins

  2. Key Concepts • Noncaloric • Essential nutrients necessary for many metabolic tasks and the prevention of certain diseases • Organic substances • Needed by body for normal metabolism, growth & maintenance

  3. Key Concepts • Vitamins do not provide energy • Vitamins work as “coenzymes” to activate other enzymes in the body

  4. Discovery: Early Observations • Discovered while searching for cures for classic diseases • Dr. James Lind, 1753 • Sailors dying on long voyages without fresh food • Scurvy = deficiency vitamin C, causes severe bleeding • Lemons and limes provided, no one became ill

  5. Era of Vitamin Discovery • Most vitamins discovered in early 1900’s • At first scientists assigned letters to each vitamin • A, C, D, E, K • This practice was abandoned in favor of more specific names • Riboflavin, niacin, thiamine, etc.

  6. Definition of Vitamin • vital, organic substance • only necessary in extremely small amounts. • cannot be manufactured by the body in sufficient quantities to sustain life • Vitamins = micronutrients • Carb/fat/protein = macronutrients

  7. Function of Vitamins • 1. Metabolism: coenzyme needed for metabolism • 2. Tissue & Bone building • 3. Prevention of deficiency diseases • Scurvy, beri beri, pellagra

  8. Vitamins:Classes • Fat soluble (vit. A,D,E,K) • Best absorbed when eaten with fat • May be stored for long periods in liver and adipose tissue • ie: Vit A best absorbed w/ whole milk • Water soluble (vit. B,C, folate) • Easily absorbed by intestinal cells and transported by the portal (liver) circulation • Not stored, so must be eaten on regular basis

  9. Fat-Soluble Vitamins:Vitamin A • Functions • Vision (healthy retina, prevent macular degeneration) • Immunity (production of immune cells, fight infection) • Growth (of muscle and soft tissue) • Deficiency: NightBlindness • Toxicity symptoms: IU= 3000mcg/day, liver damage, joint pain, headaches • Food sources: Liver, egg yolk, milk fat, butter • Stability – cooking veggies can inactivate vit A • *best absorption w/ fat

  10. Vitamin D • Functions • Absorption of calcium and phosphorus • Bone mineralization • Requirements: none if exposed to sun • Deficiency: Rickets (malformation of long bones in kids) and osteoporosis • Deficiency rare – milk is fortified w/ Vit. D • Toxicity: unusual, kidney damage • Food sources: Milk, margarine

  11. Vitamin D • OTC vitamin D (ie: Caltrate w/ D) • From a plant source • Humans lack enzyme needed to adequately absorb vit. D • We only absorb about 1% • Rx vit. D much more effective – Drisdol given orally, weekly or monthly recommended for US residents living north of Virginia, less daily sunshine **Kidneys must activate Vit. D first

  12. Child with Rickets

  13. Vitamin E • Functions • Antioxidant (prevents oxidation of molecules & prevents free radicals from changing healthy cells, accepts oxygen) • Deficiency: Hemolytic anemia (breakdown of RBC), premature infants • Toxicity: none • Food sources: vegetable oils, nuts, avocado, fortified cereals

  14. Vitamin K • Functions • Blood clotting • Bonedevelopment • Requirements: intestinal bacteria produces vit. K • Deficiency: Uncommon, newborns, long term antibiotic use • Toxicity: none • Food sources – green, leafy vegetables • Spinach, broccoli, turnip greens)

  15. Water-Soluble Vitamins: Vitamin C (Ascorbic Acid) • Functions • Build connective tissue (collagen) • Antioxidant function (protect from free rad.) • Helps w/ absorption of iron • NOT truly proven to treat colds & URI’s • Requirements: More w/ preg, lactation, smokers • Deficiency: Scurvy • Toxicity: tissue, gum bleeding, soft teeth, poor wound healing • Food sources – strawberries, melon, oranges, • tomato, broccoli, potato, peppers, cabbage

  16. Thiamin (Vitamin B1) • Functions **needed for utilization of energy, helps metabolize carbohydrates • GI system (normal appetite, digestion and elimination) • CNS (alertness, normal reflexes) • CV (normal function) • Requirements: increased in pregnancy • Deficiency: Alcoholism, Beriberi (CNS) • Food sources: beef, pork, enriched grains, legumes

  17. Riboflavin (Vitamin B2) • Functions • Energy production • Tissue building • Requirements: increased w/ preg. & lactation • Deficiency: usually occurs with protein malnutrition • Toxicity: none • Food sources: Milk !

  18. Niacin (Vitamin B3) • Functions • Energy production (extracts energy from CHO, fat, prot.) • Helps to improve lipid levels • Requirements: higher w/ preg., lact. • Deficiency: Pellagra (4 D’s) • Toxicity: from supplements = reddened skin w/ itching and burning • Food sources: meat, poultry, fish, whole grains

  19. Niacin Defeciency 4 D’s Pellegra • Dermatitis • Diarrhea • Dementia • Death

  20. Folate • Functions • Regulation of blood homocysteine levels – high levels can cause CV disease ! • Reduces likelihood of neural tube defects in unborn • Requirements: 400 mcg/day. Pregnant women, women of child bearing age should take in dietary form + supplements = 600mcg/day • Deficiency diseases:Neural tube defects (spina bifida, anencephaly) • Toxicity: minimal, some nerve damage • Food sources–green leafy veg, beans, OJ

  21. Vitamin B12 (Cobalamin) • Functions • Regulation of blood homocysteine levels • Hemoglobin production • Nervous system functioning • Requirements: higher w/ preg, lact. • Deficiency: Pernicious anemia (irreversible nerve damage) • Toxicity: none • Food sources: lean meats, clams, oysters, crab

  22. Vitamin Supplementation • Ongoing debate……yes or no ?? • Biochemical individuality: the body’s chemical composition varies for each person, this also changes based upon: • Life cycle needs • Pregnancy and lactation (folic acid +++) • Infancy (vit K at birth) • Children and adolescents (rapid growth) • Aging (decreased food intake)

  23. Vitamin Supplementation, cont’d • Lifestyle • Oral contraceptive use (may lack B & C) • Restricted diets (vegetarians – may lack B12) • Exercise programs (may need more riboflavin) • Smoking (need more vit. C) • Alcohol (thiamin, folate) • Caffeine (4-6 c/day coffee = diuretic effect – may lack B’s) • Disease (increased nutrient needs)

  24. Vitamin Supplementation, cont’d • Megadoses • Toxicity: megadose of fat soluble vitamins (vit. A) - liver/brain damage **fat sol. – stored in body • Vit. B6 - folate (over 5 gm/day) - severe nerve damage • Vit. C (ascorbic acid) (over 2 gm/day) -kidney stones

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