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A vitamin
1. A vitamin is an organic compound required by an organism as a vital nutrient in limited amounts. An organic chemical compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet.
2. Vitamins have diverse biochemical functions. Some have hormone-like functions as regulators of mineral metabolism (such as vitamin D), or regulators of cell and tissue growth and differentiation (such as some forms of vitamin A). Others function as antioxidants (e.g., vitamin E and sometimes vitamin C). The largest number of vitamins (such as B complex vitamins) functions as precursors for enzyme cofactors that help enzymes in their work as catalysts in metabolism.
3. Until the mid-1930s, when the first commercial yeast-extract vitamin B complex and semi-synthetic vitamin C supplement tablets were sold, vitamins were obtained solely through food intake, and changes in diet (which, for example, could occur during a particular growing season) usually greatly altered the types and amounts of vitamins ingested. However, vitamins have been produced as commodity chemicals and made widely available as inexpensive semisynthetic and synthetic-source multivitamin dietary and food supplements and additives, since the middle of the 20th century.
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Vitamin D facilitates hormones production.
Different vitamins accomplish similar functions.
Vitamins have been widely applied by people for a century.
Vitamins are vitally important for people.
