Monday, August 22, 2011

Do antioxidant supplements cut mortality risk?

Users of antioxidant vitamin supplements may be at reduced risk of cancer mortality, as well as premature death in general, suggests data from the European Prospective Investigation into Cancer and Nutrition. Antioxidant vitamin supplement use at the start of the study was associated with a 48 percent reduction in the risk of cancer mortality over 11 years of study, according to the European Journal of Nutrition study. In addition, the risk of all-cause mortality was reduced by 42 percent in people who were supplement users at the start of the study, report scientists from the German Cancer Research Centre and the University of Zurich.

Past antioxidant studies have been consistent with this finding and others are not. Why? The methodological challenge of conducting observational studies on the effect of dietary supplements is great and fraught with serious confounding variables.

An attempt to bring together the science was made in 2007, with the publication of a meta-analysis in the Journal of the American Medical Association which concluded that vitamins A and E, and beta-carotene may increase mortality risk by up to 16 per cent. On the other hand, vitamin C did not have an effect on mortality and the antioxidant mineral selenium was associated with a nine per cent decrease in all-cause mortality.

Recently, a team of internationally renowned antioxidant scientists re-analyzed the data used by JAMA and arrived at a different set of conclusions. The re-analysis, published in Nutrients, found that 36 percent of the trials showed a positive outcome or that the antioxidant supplements were beneficial, 60 percent had a null outcome, while only four percent found negative outcome.

So it would seem that antioxidant supplement data now supports cancer prevention and all cause mortality risk.

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