Chapter 7 Vitamins 1

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 2

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

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 4

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. 5

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 6

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

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 8

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: Night Blindness 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 9

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 10

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 11

Child with Rickets 12

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 13

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

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 15

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 16

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

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 18

Niacin Defeciency 4 D’s Dermatitis Diarrhea Dementia Death Pellegra

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 20

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 21

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) 22

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) 23

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 24