2. Vitamins and minerals Learning objectives Understand why V/M are essential to healthy living; Understand that there are healthy intake levels for V/M and that excesses may be worse than deficiencies; Know the four fat soluble vitamins and basic roles; Know the water soluble vitamins we discuss in class and their roles; Know the roles of the minerals we discuss in class; Know that processing and storage may affect some vitamins more than others. What is wrong with “If a little is good, more must be better”?

3. Fat soluble vitamins ADEK Dissolve in organic solvents – methanol, gasoline etc.. Can build up because they are not excreted Absorbed during fat absorption Transported in lipoproteins Vitamin A – carotenoids and retinoids Vitamin D – cholesterol product Vitamin E – tocopherols Vitamin K – menaquinones and phylloquinones

4. Vitamins Essential organic substances Yield no energy, but facilitate energy-yielding chemical reactions If absent from a diet, it will produce deficiency signs and symptoms Preservation of vitamins in foods exposure to light, heat, air, water, and alkaline

5. Vitamin A Two general types Pre-formed retinoids are found in animal products Precursors carotenoids are found in plant products beta carotene, lutein, lycopene, others must be converted to retinoids absorbed and converted by intestinal cells

6. Absorption of Vitamin A Requires bile, digestive enzymes, integration into micelles Dependent on the fat in the diet olestra 90% of retinoids can be absorbed Only ~3% of carotenoids are absorbed so eat your carrots Intestinal cells can convert carotenoids to retinoids

7. Transport in body/storage Liver stores 90% of vitamin A in the body polar bear liver Reserve is adequate for several months Transported via chylomicrons to the liver Transported from the liver as retinol via retinol-binding protein to target tissue Carotenoids can be transported via VLDL

8. Functions of Vitamin A Night and color vision xerophthalmia Cell health and maintenance epithelial cell differentiation and division cells deteriorate without Vit A follicular hyperkeratosis Antioxidant Macular Degeneration lutein

9. The vision cycle

11. Sources of Vitamin A Retinoids - animals Liver, fish oils, fortified milk, eggs 50% of vitamin A intake is from these sources Carotenoids - plants dark green leafy yellow orange the other 50%

12. Overdose of a Vitamin? High doses of vitamin A are toxic HYPERVITAMINOSIS A 3 – 10x supplements Teratogenic – birth defects/spontaneous abortion 3x RDA Carcinogenic – some feeding trials with smokers 3 – 10x RDA Fatal dose – 12 gram

13. How much do we need? International unit (IU)-crude method of measurement Retinol activity equivalent (RAE) -current, more precise method of measurement 1 ug of retinol = 1 RAE = 3.3 IU =12 ug beta-carotene = 24 ug of other provitamin A RDA 900 REA men 700 REA women Supplement or no?