Science - August 26, 2009

Anti-oxidant supplements linked with cancer

Many people swallow anti-oxidant pills for their claimed health benefits. Now a study suggests they may promote cancer.

Anti-oxidant food supplements sell like hot cakes because of claims about their health benefits. Now a study published in Nature suggests that anti-oxidants may promote cancer. Professor of Nutrition and cancer Ellen Kampman has some reservations about the study but she's still pleased. 'We've been guessing for a while that these supplements might have a negative effect.'
'Scientists have never said that supplements such as anti-oxidants can prevent cancer. We've been skeptical ever since a Finnish study in the early nineties, which showed that high doses of betacarotene raised the risk of lung cancer among smokers. It did get into the media but was snowed under by the lobbying supplement industry.
'This Nature study suggesting that anti-oxidants can stimulate cancer comes as no surprise therefore. It is a pity that it doesn't give the kind of solid evidence I would have liked to see. Only a few anti-oxidants were studied, and not those in widely used supplements. Also, the in vitro model used by the researchers is not directly comparable with what happens in the human body. So there will have to be a lot of water under the bridge before we really know how it works. It's a pity the media pick out one study and give it a lot of attention. A combination of epidemiological, in vitro and animal experimental studies together would provide more proof. And the combined results should be communicated more thoroughly to consumers so that they don't feel they are always being told something different.
'That fruit and vegetables are healthy is in no doubt at all, even though we don't know exactly why it is so. It's probably down to a combination of substances in the right proportions, and/or the fact the vegetable foods contain fewer calories. That's why it's best to eat a varied diet and leave the anti-oxidant supplements on the shelves.' ® HW 
 

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