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Vitamin C, or ascorbic acid, a water-soluble vitamin, was first isolated (from adrenal cortex, oranges, cabbage, and lemon juice) in the laboratories of American biochemists Albert Szent-Gyorgyi and Charles King in the years 1928–33. Szent-Gyorgyi found the Hungarian red pepper to be an exceptionally rich source; citrus fruits and tomatoes are also excellent sources. Other good sources include berries, fresh green and yellow vegetables, and white potatoes and sweet potatoes. The vitamin is readily oxidized and therefore is easily destroyed in cooking and during storage. All animals except humans, other primates, guinea pigs, and one bat and bird species are able to synthesize ascorbic acid. Ascorbic acid is necessary for the synthesis of the body's cementing substances: bone matrix, collagen, dentin, and cartilage. It is an antioxidant and is necessary to several metabolic processes. Deficiency of vitamin C results in scurvy, the symptoms of which are largely related to inadequate collagen synthesis and defective formation of intercellular materials. Ascorbic acid is metabolized slowly in humans, and symptoms of scurvy are usually not seen for three or four months in the absence of any dietary vitamin C. The use of megadoses of ascorbic acid to prevent common colds, stress, mental illness, cancer, and heart disease is a continuing subject of research. A study conducted in Great Britain in 1998 found that 500 mg of vitamin C daily had pro-oxidant as well as antioxidant effects and could damage DNA, the genetic material. The recommended daily allowance for adults is 60 mg.
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