CNS Vitamins & Minerals Review Questions and Answers

Vitamin A function in the body -vision (vitamin A is a precurrsor to rhodopsin, a light receptor pigment which converts light to an electrical signal) -call differentiation -maintains structure of cells - normal growth in children -wound healing -viral infectons -maintains integrity of mucosal epithelial barrier -growth and reproduction -gene expression (retinoic acid) -lycopene inhibits cancer growth Vitamin A forms Retinoids: retinol (most bio active form), retinoids acid and retinal Retinoids vs. carotenoids Retinoids are fully active and 90% absorbed (preformed vitamin A) Carotenoids are precursors and pigments such as beta-carotene (provitamin A can be converted to A) and lycopene, lutein, astaxanthin (nonprovitamin A cannot be converted to A) Food sources of vitamin A Beef liver (6,000 mcg -3oz.), 1 sweet potato (1400 mcg), leafy greens, eggs, milk, yellow and orange veggies and fruits, cod liver oil Vitamin A digestion and absorption Animal sources enter as retinyl ester Plant sources enter as carotenoids -in duodenum hydroplanes release any fat bound to free retinol and free carotenoids -need 10 g fat to absorb 70-90% vit A Vitamin A and the _____ are absorbed in the ____________ and this requires presence of dietary ________ and _______. Carotenoids Small intestine Lipid Bile Vitamin A storage and excretion -stored in stellate cells in liver -excreted in bile & urine Vitamin A inhibitors -fiber diminishes carotenoids absorption -heat, light and air reduce vitamin A content in foods -excess vit E and zinc