Some Antioxidant Supplements May Raise Death Risk
Tuesday, February 27, 2007; 12:00 AM
TUESDAY, Feb. 27 (HealthDay News) -- For years, the word "antioxidant" has been synonymous with disease-fighting goodness for most health-conscious Americans, but too much of the compounds just might be bad for you.
A controversial new review of data from 68 studies concludes that some of the antioxidant supplements that people take to prevent or treat disease might actuallyincreasetheir risk of death.
The study, published in the Feb. 28 issue of theJournal of the American Medical Association, drew quick criticism from one independent expert.
"One of the major premises of doing such a meta-analysis is that the studies should be comparable," said Jeffrey Blumberg, director of the Antioxidants Research Laboratory at Tufts University in Boston. "Here, they looked at primary prevention, treatment, old people, young people, smokers, nonsmokers. Only when they used theirowncriteria of what was good and what was bad were they able to show an increase in all-cause mortality."
The study, led by Dr. Goran Bjelakovic of the Center for Clinical Intervention Research at Copenhagen University Hospital, Denmark, covered trials encompassing more than 232,600 participants.
It found no overall increase in death rates when all the trials were considered. But when the trials were divided into classes using the researchers' own criteria, they found an increased risk of mortality associated with beta carotene, vitamin A and vitamin E supplements. No increased risk was found for two other antioxidants, vitamin C and selenium.
"Our findings contradict the findings of observational studies claiming that antioxidants improve health," the researchers wrote. They hypothesized that eliminating free radicals might interfere with a natural defense mechanism and possibly increase the risk of death.
A representative of the supplements industry was not impressed with the study, however.
The mortality risk finding was unwarranted and the study badly flawed, said Andrew Shao, vice president for science and regulatory affairs at the Council for Responsible Nutrition, a trade association representing the dietary supplement industry.
"They included every trial under the sun," Shao said. "Some [studies] were a day long, some were several years long. The majority of trials involved very sick patients -- treatment trials that were very, very different from how antioxidant supplements are used by most consumers, which is to maintain health."
In fact, antioxidants were used to treat a variety of diseases in 47 of the trials used in the study. Those therapeutic trials included more than 68,000 participants. There were another 21 trials, involving more than 114,000 people, where people took antioxidants in hopes ofpreventingdisease.
Even then, "overall, they didn't find a mortality effect," Shao said. "Only when they divided the trials up using their own criteria were they able to come up with this statistically significant effect."