Vitamin C Capable of Damaging DNA ------------------------------------------------------------------------------
-- 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. -- The silver-list is a moderated forum for discussion of colloidal silver. To join or quit silver-list or silver-digest send an e-mail message to: [email protected] -or- [email protected] with the word subscribe or unsubscribe in the SUBJECT line. To post, address your message to: [email protected] Silver-list archive: http://escribe.com/health/thesilverlist/index.html List maintainer: Mike Devour <[email protected]>
