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Dark side of vitamin C found
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A NEW study by US scientists suggests that Vitamin C, known to be a DNA-protecting "antioxidant", is also capable of inducing the production of DNA-damaging compounds.
According to a paper published on Friday in Science magazine, Seon Hwa Lee and colleagues with University of Pennsylvania found in test experiments that vitamin C can act as a catalyst to help make a toxin that can injure DNA, the body's genetic material. However, the new findings do not mean that vitamin C causes cancer, the researchers said.
Vitamin C is known to do beneficial work in the body, including acting as an antioxidant that disarms highly reactive molecules called free radicals. In addition to damaging DNA directly, free radicals can also act indirectly.
The radicals begin by converting linoleic acid, the major polyunsaturated fatty acid in sunflower, grape, and safflower cooking oils, as well as the major polyunsaturated fatty acid in human plasma, into another compound called a lipid hydroperoxide.
When certain metal ions are present to act as catalysts, the lipid hydroperoxides degrade further, into DNA-damaging agents called "genotoxins". These compounds react with DNA, causing mutations that have been found in human tumours.
In test-tube experiments, Lee and colleagues found that vitamin C could induce the formation of genotoxins from lipid hydroperoxides, even when there were no metal ions present. If the same process occurs in intact cells, it may mean that vitamin C is capable of damaging DNA, as well as protecting it, concluded the researchers.
(Xinhua)
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