That, according to the results of a randomized, double-blind, primary prevention trial. The investigators suggest that this may be due to the lower baseline status in men.

"It has been suggested that a low dietary intake of antioxidant vitamins and minerals increases the incidence rate of cardiovascular disease [CVD] and cancer," write Serge Hercberg, MD, PhD, from Institut National de la Santé et de la Recherche Médicale (INSERM) in Metiers, France, and colleagues. "To date, however, the published results of randomized, placebo-controlled trials of supplements containing antioxidant nutrients have not provided clear evidence of a beneficial effect."

In the Supplémentation enVitamines et Minéraux Antioxydants (SU.VI.MAX) study, 13,017 French adults were randomized to receive a single daily capsule containing 120 mg of ascorbic acid, 30 mg of vitamin E, 6 mg of beta carotene, 100 µg of selenium, and 20 mg of zinc, or a placebo. The study population consisted of 7,876 women aged 35 to 60 years, and 5,141 men aged 45 to 60 years. Median follow-up time was 7.5 years.

Both groups had similar total cancer incidence (267 [4.1%] for the supplement group vs 295 [4.5%] for the placebo group), ischemic CVD incidence (134 [2.1%] vs 137 [2.1%]), and all-cause mortality (76 [1.2%] vs 98 [1.5%]). However, there was a significant interaction between sex and group effects on cancer incidence (P = .004), with a protective effect of antioxidants in men (relative risk [RR], 0.69; 95% confidence interval [CI], 0.53-0.91) but not in women (RR,1.04; 95% CI, 0.85-1.29). There was a similar trend for all-cause mortality (RR, 0.63; 95% CI, 0.42-0.93 in men vs RR, 1.03; 95% CI, 0.64-1.63 in women; P = .11 for interaction).

"After 7.5 years, low-dose antioxidant supplementation lowered total cancer incidence and all-cause mortality in men but not in women," the authors write. "Supplementation may be effective in men only because of their lower baseline status of certain antioxidants, especially of beta-carotene."

Study limitations include high number of subjects lost to follow-up, relatively high number of individuals who withdrew during the study, the possibility that some participants had their capsules analyzed, and inability to analyze differences in site-specific cancers between men and women because of low statistical power.

"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," the authors conclude. "Further investigations are needed to better understand the causes of the sex differences observed in our study."

From the results of the study, it was concluded that vitamin supplementation at nutritional doses for 7.5 years was not associated with reduced incidence of cancer or CVD incidence and overall mortality. However, men showed a protective effect for overall mortality and cancer incidence compared with women. And that there is a positive association between low baseline beta carotene levels and cancer and overall mortality in men while women do not show this association.

Source: Diabetes In Control.com.