PP9 Fat Soluble Vitamins

PP9 Fat Soluble Vitamins - VITAMINS • Defining a vitamin...

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Unformatted text preview: VITAMINS • Defining a vitamin – Essential organic substances – Body cannot synthesize enough to maintain health – Absence from the diet will produce deficiency signs and symptoms • Yield no energy, but facilitate energy-yielding chemical reactions • May be fat- or water-soluble • Natural and synthetic Figure 10.11 Storage of Vitamins in Body • Excess Fat-soluble are generally stored – except vitamin K • Excess Water-soluble are generally excreted – except vitamin B12 and B6 • Vitamin deficiency occurs when that vitamin is lacking in the diet and body stores are exhausted Vitamin Toxicity • Unlikely to develop toxicity of any vitamin unless individual vitamin supplements are used • Toxicity of vitamin A is most possible – organ meats • Balanced multivitamin and mineral supplement supplies < 2 x RDA • Vitamin supplements are meant to supplement, not replace food based intake • Supplements do not have to be consumed daily – adjust according to need Fat Soluble Vitamins Vitamin A Status depends on: • Storage : 90% in liver (several months worth); transported to tissues where it functions • Protein status : Retinol-binding protein (RBP) Foods : • Preformed: retinol, retinal, retinoic acid – Liver, fish oils, fortified milk, eggs, other fortified foods – Contributes ~70% of vitamin A intake for Americans • Carotenoids(3/600 are Provitamin A) – Dark leafy green, yellow-orange vegetables/fruits Figure 9.2 Functions of Vitamin A (preformed) • Vision – Structural components • Retinoic acid for differentiation of cells – cornea, retina (rods and cones) – Vision cycle • Retinal in rhodopsin (in rods) • Bleaching process • (Night blindness) • (Xerophthalmia) – (Carotenoids and macular degeneration) Functions of Vitamin A (preformed) • Cell differentiation – Retinoic acid, nuclear binding, and gene expression – Important for cell differentiation – epithelium • Growth and development – Important for embryo devpt – Bone growth - bone remodeling – Sperm development • Immunity • Vitamin A analogs in dermatology Figure 9.4 Deficiency of Preformed Vit A • Who: alcoholics, people with fat...
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This note was uploaded on 10/12/2009 for the course BIBC BIBC120 taught by Professor Chilukuri during the Spring '08 term at UCSD.

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PP9 Fat Soluble Vitamins - VITAMINS • Defining a vitamin...

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