维生素作用来源及吸收（Sources and absorption of vitamins）.docVIP

维生素作用来源及吸收（Sources and absorption of vitamins） Vitamin A-- eye friend Vitamin A, also known as retinol or retinol, is a fat soluble fat soluble vitamin that is resistant to heat and readily oxidized in the air. First, the main physiological functions of vitamin A 1. vitamin A is the synthesis of rhodopsin raw material, the material is a kind of sensitive material, exist in the retina. Lack of vitamin A can not be synthesized enough rhodopsin, will lead to night blindness. 2. helps protect the skin, nose, throat, respiratory organs, the digestive system and urogenital epithelial tissue, and protect against infection. 3., with vitamin D and calcium and other nutrients to maintain the skeleton, teeth growth and development. 4. prevent goiter. 5. cholesterol necessary for the synthesis of cortisol and glycogen. Two. Dietary vitamin A deficiency affects health Because vitamin A is a major component of the visual pigments, and lack of vitamin A can cause night blindness. Vitamin A deficiency can also cause dry eye disease and can cause vision loss. In addition, vitamin A deficiency can cause slow growth of children, abnormal development of bones and teeth, dry skin, diarrhea, increased kidney and bladder stones, and reproductive disorders. Excessive intake of vitamin A will cause poisoning, poisoning symptoms were anorexia, headache, blurred vision, irritability, dry skin, hair loss, nausea, diarrhea, liver and spleen; pregnant women such as excessive intake of vitamin A, more likely to have congenital malformations in infants. Three. Daily recommended amounts of vitamin A and sources of food Vitamin A daily recommendations and food sources are shown in the following table: Recommended daily quantity of food sources Age, vitamin A, liver, egg, milk, carrot, beet, cabbage, mustard, spinach, pumpkin, sweet potato, zucchini, apricot, peach, crab and Halibut Baby 0--1 200 Children 1--10 300--1000 Adult 1000 Pregnant woman 1000 1200 nurse Vitamin D-- Zhuanggu guard Vitamin D i