PUBH 1517 - Vitamins - Vitamins Vitamins Fat Soluble...

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Unformatted text preview: Vitamins Vitamins Fat Soluble Vitamins Vitamins Vitamins Vitamins Definition: essential, noncaloric essential, nutrients, needed in tiny amounts in the diet the Classes Fat Soluble: A,D, E, K Water Soluble: B Vitamins & Vitamin C Vitamin A Vitamin Retinol, Retinal, Retinoic acid Provitamins A: beta carotene & others Functions Vision Growth & development Development & maintenance of epithelial Development tissue tissue Immune functions Reproduction Vitamin A’s Role in Vision Vitamin Component of pigment rhodopsin in Component rhodopsin the retina. Vitamin A is cleaved off of rhodopsin when light hits retina, initiating signal that conveys sensation of sight. sensation Deficiency results in accumulation of Deficiency the protein keratin in the cornea keratin (keratinization), causing cloudiness of vision and eventual blindness if deficiency not corrected. deficiency Other Vitamin A Roles Other Epithelial tissue: promotes process of cell promotes differentiation differentiation Immune system: possible role in possible regulation of genes that produce proteins involved in immunity involved Bone growth: iimportant role in bone mportant remodeling process (dismantling steps) remodeling Vitamin A Vitamin Adult RDA: 700 RAE females 900 RAE males 1300 RAE lactating 1st 6 months Deficiency symptoms Night blindness initially, xeropthalmia later Impaired immunocompetence Follicular hyperkeratosis The Skin in Vitamin A Deficiency Sources of Vitamin A Sources Food Liver, beef, 3.5 oz RE RE 10,602 Sweet potato, baked 2,487 2,487 Carrots, raw, one 2,025 2,025 Spinach, cooked, ½ cup 737 737 Canteloupe, 1 cup 515 515 Vitamin A Absorption & Transport Absorption Vit A & carotenoids released from proteins in Vit stomach stomach Retinyl esters hydrolyzed to retinol in small Retinyl intestine, then re-esterified in mucosal cells intestine, Carotenoids cleaved in mucosal cells into Carotenoids retinaldehyde, reduced to retinol, then esterified to retinyl esters for transport in chylomicra in lymph chylomicra 50 to 80% of body’s vit A stored in liver bound 50 to Cellular Retinol Binding Protein (CRBP) to Mobilized from liver as retinol bound to RBP Vitamin A Toxicity Vitamin UL: 3000 RAE for adults, 2800 for teens Symptoms Hydrocephalus & vomiting (infant or child) Bone pain and fragility Dry, fissured skin, hair loss, brittle nails Anorexia, irritability, fatigue Gingivitis Abnormal liver function with very high levels Vitamin A Toxicity Vitamin Can cause malformations in fetus, so Can pregnant women should avoid intakes over 10,000 IU per day over Cannot become toxic from carotenoids Can accumulate carotenoids in skin, Can which results in “Hypercarotenodermia” which Can differentiate from jaundice by whites Can of eyes of Vitamin A: Deficiency and Toxicity ...
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