Vitamin C Capable of Damaging DNA

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Vitamin C Capable of Damaging DNA

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WESTPORT, CT (Reuters Health) Jun 14 - While vitamin C is a known dietary

antioxidant, it can actually induce the decomposition of lipid hydroperoxides to

DNA-mutating compounds known as genotoxins, according to a report published in

the June 15th issue of Science.

Dr. Ian A. Blair and colleagues, from the University of Pennsylvania in

Philadelphia, performed several laboratory assays to determine the role of

vitamin C in lipid hydroperoxide decomposition.

Typically, certain metal ions are needed to catalyze lipid hydroperoxide

decomposition into genotoxins, the authors state. However, when vitamin C is

present, the reaction proceeds in the absence of the metal ions.

" The antioxidant effect of vitamin C is against hydrogen peroxide, " Dr. Blair

told Reuters Health. " In fact, almost all vitamins that have been tested for

antioxidant effects have been tested against hydrogen peroxide, " he said. " No

one has really considered what would happen when tested against a lipid

peroxide. "

" Vitamin C will stop the first step in lipid peroxide formation, but if the

lipid peroxide can be formed by an alternative mechanism, then vitamin C isn't

going to work, " Dr. Blair pointed out. The cyclooxygenase and lipooxygenase

pathways are two alternative ways of generating lipid hydroperoxides, he said.

" Interestingly, cyclooxygenase-2 is upregulated in colon cancer. "

" This may be the first truly convincing evidence that vitamin C has two effects,

one of them good and one of them bad, " Dr. Blair stated. " This may be why it has

never shown any efficacy " as a cancer chemoprevention agent, he added. " The bad

effects may be cancelling out the good effects. "

Science 2001;292:2083-2086.