lecture 3-18 ntr sec3 - Vitamins 1. 2. 3. 4. organic...

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Vitamins 1. organic compounds 2. Needed in small amounts in diets for growth and maintenance 3. Essential for life 4. there’s a total of 14 vitamins Water soluble (10) Fat soluble (4) Absorption Directly into blood 1 st into lymph then blood Transportation Travel freely Require protein carriers or lipid carriers Storage Minimal Liver for vit. A and D; adipose tissue for vit. E; vit. K is not stored Excretion Yes Less excreted; have to be metabolized Toxicity Yes; usually from supplements Yes, vit. A and D Requirements Need frequent doses deficit symptoms appear in days Need periodic doses precursors Tryptophan is for niacin Pro vitamin A= beta-carotene 7- dehydrocholesterol=precursor for vit. D Deficiencies Reasons: 1. failing to ingest variety of food 2. inadequate absorption a. need extrinsic factor for B-12; age decreases factor 3. increase requirement a. alcoholics need more B-1 b. cigarette smokers need more vit. C At risk Groups 1. pregnant and lactating women a. great demand for vitamins
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lecture 3-18 ntr sec3 - Vitamins 1. 2. 3. 4. organic...

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