It is the common belief that if a little is good then more must be better. Many substances though that provide beneficial effects to the body can be harmful or even deadly in large amounts. Even water or oxygen can be harmful or deadly in high amounts or in the right circumstances.
Megadosing of vitamin C is a relatively common practice especially among cancer patients. The belief is that large amounts of vitamin C can boost the immune system, and protect the body from free radical damage safely because the excess vitamin C will be eliminated from the body. How much of this is true though and are there any risks?
Vitamin C does boost the immune system and can help protect the body from some free radical damage. It is also true that excess vitamin C can be eliminated from the body. Despite this the practice of vitamin C megadosing does present some safety issues.
A severe deficiency of vitamin C can lead to a disease known as scurvy. Symptoms of scurvy include connective tissue breakdown, bleeding, muscle weakness, impaired wound healing and nervous system disorders. It is believed that megadosing of vitamin C for extended periods of time then drastically reducing the dose or going off cold turkey may lead to a condition known as rebound scurvy. Rebound scurvy is believed to occur when the body continues to excrete large amounts of vitamin C when megadoses are no longer being supplemented. Very few cases of rebound scurvy have been reported though and information about the cases have not been well-documented.