PROVIDENCE, R.I. [Brown University] Even miniscule amounts of chromium 6 can cause cancer. Blame that do-gooder nutrient, vitamin C.

Brown University researchers have discovered that naturally occurring vitamin C reacts inside human lung cells with chromium 6, or hexavalent chromium, and causes massive DNA damage. Low doses of chromium 6, combined with vitamin C, produce up to 15 times as many chromosomal breaks and up to 10 times more mutations forms of genetic damage that lead to cancer compared with cells that lacked vitamin C altogether.

This finding is startling, said Anatoly Zhitkovich, an associate professor of medical science at Brown who oversaw the experiments. Outside cells, Zhitkovich said, vitamin C actually protects against the cellular damage caused by hexavalent chromium, the toxic chemical that starred as the villain in the true-to-life Hollywood drama, Erin Brockovich. In fact, vitamin C has been used as an antidote in industrial accidents and other instances when large amounts of chromium are ingested.

Vitamin C works protective wonders because it is a powerful antioxidant, blocking cellular damage from free radicals. Specifically, the vitamin rapidly "reduces," or adds electrons, to free radicals, converting them into harmless molecules. This electron transfer from vitamin C to chromium 6 produces chromium 3, a form of the compound that is unable to enter cells.

But what happens when chromium and vitamin C come together inside cells? Because vitamin C isn't found in cells grown in a lab, Zhitkovich and his team conducted experiments using human lung cells supplemented with vitamin C. They learned that when vitamin C is present, chromium reduction has a very different effect. Cellular vitamin C acted as a potent toxic amplifier, sparking significantly more chromosomal breaks and cellular mutations.

"When we increased the concentration of vitamin C inside cells, we saw progressively more mutat
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Contact: Wendy Lawton
Wendy_Lawton@brown.edu
401-863-1862
Brown University
12-Mar-2007