CHICAGO – Low-dose antioxidant supplementation may reduce the risk of cancer among men, but not in women, according to an article in the November 22 issue of The Archives of Internal Medicine, one of the JAMA/Archives journals.
According to the article, antioxidants including beta carotene, ascorbic acid, vitamin E, selenium, and zinc may prevent some of the harmful effects caused by free radicals – reactive molecules produced by metabolism in the body. It has also been suggested that a low dietary intake of antioxidants increases the incidence of cancer and cardiovascular disease.
Serge Hercberg, M.D., Ph.D., of the Institut National de la Sante et de la Recherche Medicale (INSERM) and Unite de Surveillance et d'Epidemiologie Nutritionnelle, Paris, and colleagues tested the efficacy of dietary supplementation with a combination of antioxidant vitamins and minerals in reducing the incidence of cancer and cardiovascular disease among 13,017 French adults. There were 7,876 women aged 35 to 60 years old, and 5,141 men ages 45 to 60 years old included in the study. Participants were randomly assigned to take either a daily capsule containing 120 milligrams of ascorbic acid, 30 milligrams of vitamin E, six milligrams of beta carotene, 100 micrograms of selenium, and 20 milligrams of zinc; or a placebo capsule. Participants were followed-up for a median of 7.5 years.
The researchers found no differences between the antioxidant and placebo group in terms of cancer incidence (4.1 percent of the antioxidant group vs. 4.5 percent of the placebo group), or in cardiovascular disease incidence (2.1 percent for the antioxidant group vs. 2.1 percent for the placebo group) or all-cause death (1.2 percent for the antioxidant group vs. 1.5 percent for the placebo group).
However, when the researchers looked at cancer incidence according to sex, they found a significant protective effect of the antioxidants in men, who were 31 percent less likely to develop cancer than women. A similar trend was seen in men for death rates.
"After 7.5 years, low-dose antioxidant supplementation lowered total cancer incidence and all-cause mortality in men but not in women. Supplementation may be effective in men only because of their lower baseline status of certain antioxidants, especially of beta carotene," the researchers write.
The authors conclude: "… our results suggest that an adequate and well-balanced supplementation of antioxidant nutrients, at doses that might be reached with a healthy diet that includes a high consumption of fruits and vegetables, had protective effects against cancer in men."
(Arch Intern Med. 2004;164:2335-2342. Available post-embargo at archinternmed.com)
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