Vitamin C
Vitamin C has not been shown to be beneficial in a normal population for the prevention or treatment of the common cold. Supplementation might be beneficial in people exposed to periods of severe physical exercise or cold environments. A well-known supporter of the theory that Vitamin C megadosage prevents infection was physical chemist Linus Pauling, who wrote the bestseller Vitamin C and the Common Cold in 1970.
Read more about this topic: Alternative Treatments Used For The Common Cold