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Vitamin A is normally a fat-soluble vitamin. It occurs in nature as preformed vitamin A and provitamin A (primarily beta carotene). The carotenes are converted into vitamin A in the intestines. Fat-soluble vitamin A can accumulate in the liver, causing side effects, but consuming too much carotene will not result in vitamin A toxicity. Thyroxine, zinc and vitamin E enhance the conversion of carotene to vitamin A. Water-soluble vitamin A results in higher blood levels, with less accumulation in the liver, and, though hard to find, can be used safely in much higher doses.
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Beta-Carotene: The most abundant of the carotenoids, beta-carotene has strong provitamin A activity and is a stronger antioxidant than vitamin A. It is widely accepted today as a cancer preventative. It is found in leafy green and yellow vegetables, often missing in children's diets. Beta-Carotene is believed to be a superior source of Vitamin A because it is readily converted into a more active form of the substance: your body converts it to Vitamin A as needed.
Carotene: Converted into vitamin A in the body from a yellow pigment that has several forms (i.e., alpha-, beta-, and gamma-carotene).
Chapped: Roughened, reddened, or cracked skin, especially as a result of cold or exposure.
IU: International Units. One IU is 1/40th (0.025) of a microgram (mcg).
Provitamin: A substance found in certain foods, that the body may convert into a vitamin. Also called previtamin.
Serum: The cell-free fluid of the bloodstream. It appears in a test tube after the blood clots and is often used in expressions relating to the levels of certain compounds in the blood stream.
Teratogenicity: Property of an agent that causes physical defects in the developing embryo.
Vitamin A: A fat-soluble vitamin essential to one's health. Plays an important part in the growth and repair of body tissue, protects epithelial tissue, helps maintain the skin and is necessary for night vision. It is also necessary for normal growth and formation of bones and teeth. For Vitamin A only, 1mg translates to 833 IU.
Vitamin E: An essential fat-soluble vitamin. As an antioxidant, helps protect cell membranes, lipoproteins, fats and vitamin A from destructive oxidation. It helps protect red blood cells and is important for the proper function of nerves and muscles. For Vitamin E only, 1mg translates to 1 IU.
Zinc: An essential trace mineral. The functions of zinc are enzymatic. There are over 70 metalloenzymes known to require zinc for their functions. The main biochemicals in which zinc has been found to be necessary include: enzymes and enzymatic function, protein synthesis and carbohydrate metabolism. Zinc is a constituent of insulin and male reproductive fluid. Zinc is necessary for the proper metabolism of alcohol, to get rid of the lactic acid that builds up in working muscles and to transfer it to the lungs. Zinc is involved in the health of the immune system, assists vitamin A utilization and is involved in the formation of bone and teeth.