Kin 110 Lecture 6 Vitamins Ch. 7

Vitamins Vitamin – essential organic (contains carbon) substances needed in small amounts in diet Normal function, growth, maintenance of body Yield no energy, but participate in energy yielding reactions ADEK – fat soluble B vitamins and C – water soluble B vit. And Vit K – co-enzymes – help enzymes function Fig. 7-1

Vitamins To be classified as vitamin Body unable to synthesize enough Absence for a defined period of time must produce deficiency symptoms, if caught in time, are cured when substance is reintroduced to diet Have they all been found? People living on intravenous solutions of Protein, Carbohydrates, Fat and all known vitamins and minerals survive, grow, reproduce and fight disease

Storage of Vitamins Fat soluble vitamins A and D not readily excreted Water soluble - lost from body quite rapidly (B12 stored) Limited storage – should be consumed daily

Vitamin Toxicity Toxicity theoretical for all vitamins Fat soluble more frequently observed (A and D) E, Niacin, B-6 and C – very large amounts - toxicity Only possible from supplements A and D 3-5 times daily need A – important to minimize in early pregnancy Once a day vitamins, less than 2 times daily value – not a risk Consult physician – as medications can be counteracted

Fat soluble Vitamins ADEK Absorbed along with dietary fat Travel in bloodstream along with fat to reach body cells Stored in liver and fatty tissue 40-90 % of fat sol. vit. absorbed Can be reduced further – interference in normal digestion and absorption of fats. Eg. Mineral oil laxatives

Vitamin A Easy to over dose (toxic) and be deficient Both cause sever problems Variety of forms Eg. Retinol Preformed vitamin A – retinoids animal foods Carotenoids – pro-vitamin A plants Yellow-orange pigment in carrots Turned into vitamin A as needed Most potent – beta-carotene Both pre and pro – referred to as VitaminA

Functions of Vitamin A Many roles – not all well understood Role in vision – best known and most clearly understood Performs important functions is both light (day) and dark (night) vision in dim light, one form of A is required to start the chemical process that signals the brain that light is striking the eye. Without A – night blindness Prolonged deficiency – cells unable to produce mucus Dry, dirty, scratched, infected Xeropthalmia Less-developed nations – children Blindness. Infection, death

Health of Cells Vitamin A – maintains health of all cells that line internal and external surfaces Lungs, intestines, stomach, eyes, skin (epithelial cells) Cells secrete mucus – lubricant Without A – decrease activity of immune cells, increased infection Needed for growth, Development and Reproduction Synthesis of proteins that stimulate proper growth and ddevelopment Resorption and production of bone

Cancer and Vitamin A Skin, lung, bladder and breast cancer Adequate intake of vitamin A can lower risk of breast cancer Mega dose NOT recommended Carotenoids – trap energy in free radicals – oxidation can initiate cancer process Supplements of B-carotene not effective Variety of fresh fruits and vegetables Acne – topical and internal derivatives Birth defects in pregnant women

Vitamin A in Food Preformed liver, fish oils, fortified milk and cereal, butter, margarine, eggs Pro-vitamin – dark green and orange vegetables Carrots, spinach, winter squash, papaya, apricots RDA – RE- retinol equivalent 1000 RE (males) 800 RE (females) Risk of deficiency – children, poor, alcoholics Dietary sources table – p. 214

Toxicity of Vitamin A 3 times the RDA can cause problems if continued for prolonged periods Early pregnancy (preformed) Fetal malformations, birth defects, spontaneous abortion Non-pregnant – skin, hair, internal organs and CNS Permanent damage can occur Vit A is stored for months Women in childbearing years – limit to 100% intake Carotenoids(pro) not toxic Rate of conversion is slow Efficiency of absorption decreases as intake increases

Vitamin D Also considered a hormone effects kidney and bone skin cells convert cholesterol like substance into vitamin D using sunlight effects kidney and bone 10-15 minutes of exposure of arms, face and hands; 2-3 times per week not effective in winter must have vitamin intake

Functions of Vitamin D To become active hormone, vitamin D must be activated in liver and kidneys calcitrol - active form regulates calcium and bone metabolism along with parathyroid hormone regulates absorption of calcium and phosphate from intestines reduces kidney excretion of calcium regulates deposition of calcium in bones Cancer cells influenced by vitamin D

Vitamin D and Bone Calcium and phosphorus deposition without vit D bones weaken and bow under pressure Rickets (children) fortification of milk - malabsorption of fat (cystic fibrosis) osteomalacia - adults - soft bones calcium withdrawn from bones inefficient absorption or conservation vit d deficient bones porous and weak - break easily supplement vit D - reduce fractures problem with vitamin D activation or absorption

Dietary Sources of D Fatty fish (sardines, salmon), fortified milk and cereal under 51 years - 5 ug/day over 51 2-3 times -10-15 ug/day max. 200 ug /day Young, fair skined 10-15 min 2-3 times /week 5-10 times recommended on regular basis - toxicity calcium overabsorptoin - deposition in kidneys and other organs high bld calcium weakness loss of appetite, diarrhea, vomiting , mental confusion, sun exposure does not result in toxicity

Vitamin E Fat soluble antioxidant - resides in cell membranes donates electrons - protection from free radicals fig 7-3 p 217 DNA oxidation - cancer, cell death repair mechanisms for damage impact on cancer, heart disease very minimal compared to proper diet and exercise not an alternative

Deficiency of vitamin E Cell membranes break down red blood cells in infants unsaturated fatty acids susceptible to oxidation hemolysis- breaking of rbc in absence of vit. E vit E improves vit A absorption used to metabolize iron in cell, maintain nervous tissue, and insulin function

Vitamin E in Foods plant oils, fortified cereals, fruits and veg, eggs, margarine vitamin E in plant oils - protects unsaturated fatty acids animals almost no vitamin E content of E depends on harvesting , processing storage and cooking easily destroyed by oxygen, metals , light , repeated frying RNI - 8-10 mg /day alpha tocopherol - most active form smoking destroys vitamin E megadose therapy - not proven toxicity not a problem, except with anticoagulants (cardiovascular disease)

Vitamin K Plants, fish oils, and meats synthesized by bacteria in intestine role - vital for blood clotting synthesis of blood clotting factors formation of proteins in bone, kidney and muscle impart calcium binding potential newborns lack bacteria to produce vitamin K routine injection at birth deficiency in adults on prolonged antibiotics or wit fat malabsorption

Vitamin K in Food Liver, green leafy vegetables, broccoli, peas and green beans vitamin K not stored well - one day abundant in diet, deficiency uncommon resistant to cooking RDA - 60 - 80 mg / day no risk of toxicity risk of reduced effectiveness of medications to reduce blood clotting (CV disease)

Vitamin Supplements Supplements may be beneficial, and improve health of population folate (B vitamin) birth defects homocystien - risk factor for heart disease alleviated by adequate folate (and reduction in red meat) over 50 - vitamin B12 (synthetic) easily absorbed Eat right and take a multivitamin Table 7-2 Supplements in consultation with physician

Vitamin Supplements Megadoses of E and B12 trials ongoing, may be beneficial Supplements should be taken with or just after meal no more than 100% of daily values avoid excess selenium and C overabsorption of iron males avoid excess iron excess zinc - inhibits iron an copper absorption excess folate - masks b12 deficiency avoid other products - PABA, inositol, bee pollen, lecithin Table 7-3, p 224