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 C efficiency decreases as amounts increase. Intravenous administration bypasses this. Doing so makes it possible to achieve plasma concentrations of 5 to 10 millimoles/liter (mmol/L), which far exceed the approximately 0.2 mmol/L limit from oral consumption. The theories of mechanism are contradictory. At high tissue concentrations ascorbic acid is described as acting as a pro-oxidant, generating hydrogen peroxide (HO) to kill tumor cells. The same literature claims that ascorbic acid acts as an antioxidant, thereby reducing the adverse effects of chemotherapy and radiation therapy. Research continues in this field, but a 2014 review concluded: "Currently, the use of high-dose intravenous vitamin