Vitamin C and DNA Damage Incorrectly Linked

PHILADELPHIA--In a study making the media rounds, research from the University of Pennsylvania is being hyped as finding a link between DNA damage and vitamin C. However, the research was not conducted on people, but rather in test tubes that simulated reactions that do not occur in the human body. The study is published in the June 15 journal Science (292:2083-6, 2001) (www.sciencemag.org).

In test tube assays, researchers looked at the effect of vitamin C (in amounts comparative to 200 mg/d) on lipid hydroperoxides (polyunsaturated fatty acids). DNA damage occurred when the antioxidant was added to the fatty acids, an angle that mainstream media immediately picked up.

Ascorbic acid was applied to purified polyunsaturated fatty acids that had been oxidized chemically in the laboratory--something that would not happen in a living cell in humans. "The issue here is that the researchers created a very artificial environment in these test tubes," said John Hathcock, vice president of nutrition and regulatory science at the Washington-based Council for Responsible Nutrition (CRN). "These researchers are chemists, not biologists. I don't consider this study flawed, but misdirected and over-interpreted by the media."

Even one of the study's authors, Ian Blair, is trying to defuse the bomb that mainstream media has dropped into newspapers and broadcasts across the country. In an interview with Reuters, Blair was concerned about the media sensationalizing these results. "Absolutely for God's sake don't say vitamin C causes cancer," he told the news service. In addition, Better Nutrition magazine (www.betternutrition.com), based in Stamford, Conn., was able to catch up with the sought-after doctor in Scotland. "The study is being over-interpreted," said Blair in the June 15 interview. "I've been trying to de-sensationalize the paper by referring people to other studies that have not found direct evidence of vitamin C supplementation preventing cancer."

In fact, a great amount of research has found a correlation between vitamin C and its health benefits, including recent research showing that smokers may experience reduced DNA damage when taking the vitamin (Free Radic Res 2001 Mar; 34(3):209-19). Moreover, last year the Food and Nutrition Board of the Institute of Medicine at the National Academy of Sciences (NAS) found from a comprehensive review of vitamin C studies that no evidence supports that vitamin C damages DNA in humans.

"No one can categorically say that these results can't happen in the human body," said Hathcock. "But one can't categorically say that Jupiter is not full of green cheese." He added that this study provides no reason for any consumer to stop taking vitamin C.

Foothill Ranch, Calif.-based Alacer Corp. (www.alacercorp.com), maker of the vitamin C product Emergen-C, reported having major concerns with this study. "When the author of a study backs away, I think that is pretty telling in terms of the study's applicability to human consumption," said Bruce Sweyd, director of sales and marketing at Alacer.