Antioxidant pills do nothing to prevent cardiovascular disease

Aug 2 2004

Research published in the current issue of the Journal of the American Heart Association, shows that antioxidant pills have no clear benefit in the prevention of cardiovascular disease.

Antioxidants are substances that protect components of a cell from oxidative damage that may occur from light, stress, or metabolic processes. Some well known antioxidants include compounds normally present in food such as, vitamin E, beta-carotene, the carotenoids lutein and zeaxanthin, vitamin C, zinc, and selenium.

The lead author of the research, Penny Kris-Etherton, Ph.D., said “At this time, there is little reason to advise that individuals take antioxidant supplements to reduce their risk of cardiovascular disease.” Penny is a Distinguished Professor of Nutrition in the Department of Nutritional Sciences at the Pennsylvania State University.

A review of research conducted on antioxidants between 1994 and 2002 showed that antioxidant supplements largely have no effect on preventing or treating cardiovascular disease.

The American Heart Association continues to promote a diet rich in fruits, vegetables, whole grains, fish, legumes, poultry and lean meats to derive antioxidant vitamin benefits.

“While the research shows that antioxidant supplements have no benefit, the role oxidative stress plays in the development and progression of heart disease has yet to be clarified,” Kris-Etherton said. “We still know too little about the oxidative mechanisms in humans and lack biochemical markers with which to evaluate antioxidants.”

Ongoing studies should answer important questions about the role of oxidation in atherosclerosis, she said.

Until those questions are resolved, this review presents the current science and helps clinicians understand that they should not recommend antioxidant supplements to reduce the risk of cardiovascular disease.

“We know that diets high in fruits and vegetables are associated with decreased risk of cardiovascular disease. Thus, following a diet consistent with the American Heart Association’s dietary guidelines is recommended. In addition, achieving and maintaining a healthy body weight and being physically active are important to reduce cardiovascular disease risk,” Kris-Etherton said.

The antioxidant studies reviewed fell into three headings: no effect on cardiovascular patients, adverse effects on cardiovascular patients, and beneficial effects on cardiovascular patients. The majority of the studies found antioxidants have no effect on cardiovascular patients.

The committee reviewed nine studies on vitamin E and cardiovascular disease (CVD) – five showed the supplement had no effect on CVD events, three showed beneficial effects, and one showed a negative effect. Four studies of beta-carotene were reviewed – three showed no effects on CVD and one showed a negative effect. Five studies of antioxidant “cocktails” were reviewed – two showed no effects and three showed negative effects. Finally, two studies of vitamins E and C together (one with vitamin E as alpha-tocopherol plus slow-release vitamin C and the other with vitamin E plus vitamin C) showed beneficial effects on CVD events.

Most of the patients in the studies reviewed were either heart patients or considered candidates for cardiovascular disease. As such, some patients were taking drugs to treat abnormal lipids and high blood pressure.