Vitamin C Vitamin C Vitamin C, also known as ascorbic acid and -ascorbic acid, is a vitamin found in food and used as a dietary supplement. The disease scurvy is prevented and treated with vitamin C-containing foods or dietary supplements. Evidence does not support use in the general population for the prevention of the common cold. There is, however, some evidence that regular use may shorten the length of colds. It is unclear if supplementation affects the risk of cancer, cardiovascular disease, or dementia. It may be taken by mouth or by injection. Vitamin C is generally well tolerated. Large doses may
Vitamin A Vitamin A Vitamin A is a group of unsaturated nutritional organic compounds that includes retinol, retinal, retinoic acid, and several provitamin A carotenoids (most notably beta-carotene). Vitamin A has multiple functions: it is important for growth and development, for the maintenance of the immune system and good vision. Vitamin A is needed by the retina of the eye in the form of retinal, which combines with protein opsin to form rhodopsin, the light-absorbing molecule necessary for both low-light (scotopic vision) and color vision. Vitamin A also functions in a very different role as retinoic acid (an irreversibly oxidized form of