VITAMIN C

also called Ascorbic Acid, water-soluble, carbohydrate-like substance that is involved in certain of the metabolic processes of animals. Although most animals can synthesize vitamin C, it is necessary in the diet of some, including humans and other primates and guinea pigs, in order to prevent scurvy (q.v.), a disease characterized by debility, blood changes, spongy gums, and hemorrhages in the tissues of the body. First isolated in 1928, vitamin C was identified as the curative agent for scurvy in 1932. It has since been the object of continued active laboratory research. Definitive knowledge of the details of its action is surprisingly scant, even though the vitamin is known to be essential in a variety of metabolic functions, including synthesis of collagen (a protein important in the formation of healthy skin, tendons, bones, and supportive tissues and in wound healing); maintenance of the structural strength of the blood vessels; metabolism of certain amino acids; and the synthesis or release of hormones in the adrenal glands. It has also been suggested that vitamin C plays a part in protecting the body against infection, though scientific data do not clearly support this claim. Relatively large amounts of vitamin C are requirede.g., an adult man is said to need about 70 mg per day. Citrus fruits and fresh vegetables are the best dietary sources of the vitamin. Because vitamin C is easily destroyed by reactions with oxygen, especially in neutral or alkaline solution or at elevated temperatures, it is difficult to preserve in foods. The vitamin is added to certain fruits to prevent browning.