People often supplement with vitamin C when they have a cold. According to various studies, vitamin C may be effective in reducing the duration of a cold, but does not seem to reduce the frequency of colds in a population.[1][2] The available literature suggests that a dose ranging from 200 mg to 2,000 mg could be beneficial for reducing cold duration.
Often utilized for its antioxidant effects, vitamin C has been studied for its potential role in Alzheimer’s disease and cancer. Lower vitamin C levels are present in people with Alzheimer’s, even with adequate dietary intake.[3] It is thought that oxidative stress plays a major role in the pathogenesis of the disease, so vitamin C’s antioxidative effects could be beneficial.[4][5] In rodent studies, oral vitamin C was able to reduce oxidative and inflammatory biomarkers.[6] In recent cancer research, vitamin C was found to promote oxidative stress in cancer cells, leading to cytotoxic effects at high doses in mice.[7] While promising, further research and human studies are required to determine efficacy.