MONDAY, Nov. 22, 2004 (HealthDayNews) -- A long-running French study finds that a low-dose cocktail of antioxidants reduces the incidence of cancer in men but not in women.
Antioxidants are compounds that protect cells from harm caused by highly reactive molecules, called free radicals, produced by metabolism in the body. Low dietary intake of antioxidants has been suggested to increase the risk of cancer and heart disease.
A study done by the National Institute of Health and Medical Research in Paris enlisted 7,876 women ages 35 to 60 and 4,141 men ages 45 to 60. They were randomly assigned to take either an inactive substance or a daily antioxidant capsule containing 120 milligrams of vitamin C (ascorbic acid), 30 mg of vitamin E, 100 micrograms of selenium, 6 mg of beta carotene, and 20 mg of zinc.
After an average follow-up of 7.5 years, there were no significant overall differences between the two groups, said a report in the Nov. 22 issue of the Annals of Internal Medicine. The incidence of cancer was 4.1 percent for the antioxidant group and 4.5 percent for the placebo group. The incidence of cardiovascular disease was identical in both groups, 2.1 percent. The death rate was 1.2 percent for those taking the antioxidant supplements, 1.5 percent for those taking the placebo.
But the risk of cancer was strikingly lower for men in the antioxidant group, who were 31 percent less likely to develop a malignancy than women in that group. The male death rate in the antioxidant group was also lower -- 0.63 percent for men, 1.03 percent for women.
The supplements might be more beneficial for men "because of their lower baseline status of certain antioxidants, especially of beta carotene," the researchers wrote.
John N. Hathcock, vice president for scientific and international affairs of the Council for Responsible Nutrition, offered another possible explanation. More men than women had a record of smoking, and therefore were more likely to be helped by the antioxidants, he said.
Hathcock, whose group represents the supplement industry, said the study made a good case for getting "a generous intake of all these antioxidants." Getting them by following good dietary rules is best, Hathcock said, but "these levels of nutrients are just at the boundary of what is reasonably feasible by diet."
Dr. Stephen Barrett, a retired psychiatrist who is vice president of the National Council Against Health Fraud, which runs a Web site that investigates products that make unproven health claims, took a predictably skeptical view of the value of supplements.
"If you have a lousy diet, it makes sense to pop a vitamin pill," Barrett said. "But that certainly doesn't correct a lousy diet."
Better health starts with diet, Barrett said, and the proper starting point is to "analyze your diet and compare it to the recommended dietary guidelines. You should invest one visit to your doctor to find out what you are missing in your diet. If you don't want to correct that, you can discuss how to improve it with supplements."
The French researchers' conclusion also stressed good dietary habits: "... 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."
Questions and answers on antioxidants can be found at the National Cancer Institute.