— Millions of Americans taking popular antioxidants in the hope of preventing heart disease may be putting themselves at risk.
A new analysis published in The Lancet medical journal today found vitamin E and beta-carotene are ineffective in protecting against heart disease and other causes of death.
The research, carried out at the Cleveland Clinic, also found that such supplements could be harmful to certain people, supporting previous criticism in the medical community of the widespread use of antioxidant pills.
"I have been surprised how difficult it has been for patients to give [antioxidant vitamins] up," says Dr. Lori Mosca, director of the preventive cardiology unit of New York Presbyterian Hospital. "This study adds to the growing body of data that [not only is there no] benefit but potential harm with antioxidant vitamins."
Early Warning Signs
Dr. B. Greg Brown, professor of cardiology at the University of Washington in Seattle, pointed to trials several years ago that he said should have served as an early warning sign.
"About 1995, large randomized trials appeared which showed no benefit [to taking these vitamins] and, in fact, small adverse trends. But by that time, the hypothetical benefit was now 'fact' in the minds of the physicians and their patients, who continued vitamin use despite the real facts. … There are many patients that continue, with blind faith, to take antioxidant vitamins to prevent heart disease or cancer," Brown said.
The Cleveland Clinic team's analysis of 12 previous clinical trials investigating the effects of vitamin E and beta-carotene did not find that these supplements increased cardiovascular or overall health. It found that beta-carotene supplements slightly increased the odds of death, mainly among smokers who were at risk of lung cancer.
Earlier studies had shown a significant benefit to taking antioxidants such as vitamin E and beta-carotene, fueling the natural supplement craze that continues to sweep the nation.
Dr. Mark Ebell, professor at Michigan State University and editor of American Family Physician, noted: "I bet if you ask patients, 90 percent of those who have an opinion think [taking antioxidant supplements] helps. Many physicians think it helps as well. … For example, I had a patient yesterday whose cardiologist had just told him to take vitamin E. I told him it wasn't necessary, but since the cardiologist is the 'expert' I'm not sure he'll believe me."
Vitamin E Widely Recommended, But Why?
A 2001 survey by the Council for Responsible Nutrition found that 75 percent of cardiologists recommend vitamin E to their patients.
Dr. Richard Roberts, professor of family medicine at the University of Wisconsin medical school, estimated that about 15 percent of his adult patients took vitamin E for heart disease prevention.
"The vast majority take 400 IU daily, which is unlikely to do them much harm, … [though] it's not likely to do them much good either," Roberts said.
Nineteen percent of American adults regularly take a vitamin E supplement, according to a recent survey by the Hartman Group.
Where Past Studies Went Wrong
Researchers believe that the previous studies showing benefits to taking antioxidant supplements might have failed to account for the other nutrients in antioxidant rich foods such as broccoli, carrots and peaches.
Another possibility is that the respective studies do not distinguish between primary and secondary prevention. The results of this particular paper focus on secondary prevention, or helping patients that already exhibit symptoms of disease, whereas previous reports have examined the effects of antioxidants on healthy patients.
Still, physicians generally agree that the benefits of taking vitamin E for adult patients are likely very small.
In light of this and other recent studies calling into question the efficacy of antioxidant supplements, many physicians are now following the example of Brown, who said: "One of the adverse aspects of antioxidants, aside from their small detrimental effects, is that they provide a diversion away from proven therapies for these conditions. … My clinical policy is to tell my patients that antioxidant vitamins are of no proven value against heart disease or cancer."