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Vitamin C, also known as ascorbic acid or ascorbate, plays two important roles in the body. First, it is a cofactor or cosubstrate for eight enzyme systems involved in various functions, including collagen synthesis, ATP synthesis in mitochondria, and hormone biosynthesis. Second, vitamin C is a powerful water-soluble antioxidant with a vital role in protecting cells and tissues from damaging oxidizing agents, including superoxides, hydroxyl radicals, and other oxygen free radical species. All these functions derive from one fundamental property: vitamin C is a powerful reducing agent (or electron donor) capable of neutralizing reactive oxidants.
Related functions performed by vitamin C include the following: it assists in the regeneration of vitamin E, it promotes iron absorption in the intestines by keeping iron in its reduced form, and it is thought to play roles in regulating DNA transcription and protein synthesis.
The richest dietary sources include cantaloupe, grapefruit, honeydew, kiwi, mango, oranges and other citrus fruits, strawberries, and watermelon. The richest vegetable sources include asparagus, broccoli, brussels sprouts, dark green leafy vegetables, and peppers.
Although vitamin C is generally non-toxic, very high dosages (generally several grams) may cause or contribute to gastrointestinal distress and diarrhea.
For additional information (including a list of references), please refer to the vitamin C technical bulletin at http://www.usana.com/dotCom/company/science/components.
Vitamin C - U.S. National Library of Medicine
Vitamin C - Physicians' Desktop Reference
Vitamin C - Mayo Clinic
Vitamin C - Linus Pauling Institute
Vitamin C - Wikipedia
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