Lecture 1 notes - Module 4: Vitamin A deficiency Lecture 1:...

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Unformatted text preview: Module 4: Vitamin A deficiency Lecture 1: Vitamin A 1. What is food? Food is composed of: Carbohydrate, protein, fat Vitamins Macrominerals and microminerals Phytochemicals Is food a drug? Functional foods Nutraceuticals Genetically modified foods 2. What are vitamins? "vita" = life "amine" = nitrogen containing (not all vitamins) complex organic substance required in very small quantities in diet relative to other nutrients accessory growth factor Nomenclature and properties of vitamins essential because body cannot produce them at all, or in sufficient quantities (ie. D & K) 13 vitamins proven to be essential not chemically related and differ in physiological roles classified by solubility water vs fat influences mode of action , storage and toxicity Metabolism of vitamins Step Fat Soluble Water Soluble Digestion- similar to lipids/bile acids- de-esterified- none Absorption- with lipids- variable: active, passive, energy-dependent Transport in Blood- specific proteins, lipoproteins- in free form- specific binding proteins Storage- mostly liver, some adipose - none EXCEPT B 12 is stored in liver Utilization /Function Individualized functions:- HORMONES: A & D- ANTIOXIDANTS: E and B-carotene- COENZYMES in energy & protein/amino acid & nucleic acid metabolism- COSUBSTRATES in enzymatic reactions- ANTIOXIDANT- vit C Excretion- via liver & bile- in urine mostly in unchanged chemical form Deficiency- related to reduced intake or increased need eg. vitamin D deficiency rickets- dietary deficiency due to food choice or processing losses eg. refining flour Toxicity- A & D quite toxic as stored in liver- E & carotene not toxic as stored in adipose- non-toxic as not stored in body excess intake excreted in urine Pharmacological Use A/carotene cancer A (retinoic acid ) acne Vit C cancer & colds 3. 3....
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Lecture 1 notes - Module 4: Vitamin A deficiency Lecture 1:...

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