Too much vitamin C

Those who think that if a little vitamin C is good, more must be better should think again, says a team of British researchers, who found that a supplement of 500 milligrams a day could damage people's genes.
Many Americans take that much, or more, in hopes of preventing colds and reaping the widely celebrated antioxidant benefits of vitamin C. Antioxidants, which block cellular and molecular damage caused by the highly reactive molecules called free radicals, are believed to protect against heart disease, cancer, eye disorders like cataracts and macular degeneration, and other chronic health problems.
But the British researchers, chemical pathologists at the University of Leicester, found in a six-week study of 30 healthy men and women that a daily 500-milligram supplement of vitamin C had pro-oxidant as well as antioxidant effects on the genetic material DNA. The researchers found that at the 500-milligram level, vitamin C promoted genetic damage by free radicals to a part of the DNA, the adenine bases, that had not previously been measured in studies of the vitamin's oxidative properties.