Free radicals are normal by-products of metabolism, but they can cause chain reactions that result in cell damage. This cell damage can, in turn, increase the risk of chronic diseases, including certain forms of cancer and cardiovascular disease.
Antioxidants have the ability to stop this chain reaction. Vitamin C functions in the body as an antioxidant. Because of this antioxidant capability, vitamin C is being studied for a possible role in prevention of certain conditions like age-related macular degeneration, cataracts, cancer, and cardiovascular diseases. Currently there is not sufficient evidence to recommend vitamin C for any of these conditions.
Many people believe that taking mega-doses of vitamin C will cure a
cold. There is no scientific evidence to support this idea in the general population. However, there may be some preventative benefit in people exposed to extreme physical stress, cold environments, or those not getting enough vitamin C normally. Studies have found that taking vitamin C daily may help slightly reduce the symptoms and the duration of a cold. But taking vitamin C after the onset of the cold does not appear to effect the course of the illness. In addition, a review of studies on vitamin C found that it may be able to prevent and treat
pneumonia, particularly in people who do not get enough vitamin C in their diet.