FatSoluble Vitamin脂溶性维生素.pptVIP

Fat-Soluble Vitamins A, D, E, K Fat-Soluble Vitamins found in fats and oils require bile for absorption enter the lymph, then the blood held and stored in fatty tissues daily requirements need not be met may reach toxic levels not readily excreted Vitamin A 3 forms in the body retinol retinal retinoic acid collectively known as retinoids found in food derived from animals Vitamin A precursor: beta-carotene derived from plant foods can split and form retinol in intestine and liver Vitamin A promote vision small losses of retinal requires continual replenishment maintain epithelial tissue and skin mucous membranes support reproduction and growth sperm development fetal development Vitamin A deficiency infectious disease pneumonia, measles, diarrhea keratinization dry, rough, scaly skin night blindness Vitamin A toxicity yellow skin: too much beta-carotene excess stored under skin in fat weaken bones found in colorful vegetables liver Vitamin D body can make from sunlight precursor made from cholesterol not essential production occurs in liver and kidney diseases can affect activation Vitamin D target tissue intestines, kidneys, bones part of the bone-making/maintenance team maintains blood concentrations of Ca P deficiencies ultimately creates a calcium deficiency Vitamin D toxicity most common in vitamin D excess vitamin D = increase in blood calcium = stones or hardening of blood vessels Vitamin D sources fortified food: milk, margarine, cereals, beef, eggs sun 10-15 minutes several times a week dark pigmented skin needs more 3 hours = 30 minutes storage from the summer does not last the winter Vitamin E antioxidant defender against free radicals polyunsaturated fatty acids may reduce the risk of heart disease deficiencies rare erythrocyte hemolysis preemies – destruction of red blood cells Vitamin E toxicity rare may interfere with blood-clotting mechanisms of vitamin K widespread in food easily destroyed by heat processing Vitamin K aids in blood clotting