Antioxidants such as beta-carotene and vitamin E don't lower the risk of dying from heart disease, and beta-carotene may even slightly increase the risk, according to a new analysis of studies conducted in the past.
As a result, researchers at the Cleveland Clinic Foundation said the use of supplements containing beta-carotene and vitamin A (a beta carotene metabolite) should be actively discouraged and that clinical studies using the antioxidant be discontinued. In addition, they also discourage similar investigations involving vitamin E for heart disease treatment or prevention.
But the conclusions of the new study sparked criticism from one antioxidant expert, Dr. Jeffrey Blumberg of Tufts University in Boston, Massachusetts. "No new research has been conducted and this is why their conclusions are so surprising," he said.
In the study, the researchers reviewed seven previously published trials of vitamin E treatment and eight trials of beta-carotene treatment. All of the trials included at least 1,000 patients and were trials in which patients were randomly assigned to take the supplements or a "control" treatment. Vitamin E did not reduce the risk of stroke or dying of heart disease and made no difference in the risk of death due to any cause.
Beta-carotene users actually had a slight increase in the risk of death due to any cause and the risk of death due to heart disease. The researchers note that the small harmful effect seen for beta carotene was largely due to two studies that included a lot of smokers. Scientists have known the potential risks beta-carotene poses to smokers for some time. However, beta-carotene is quite safe to nonsmokers.
Opthalmologists recommend large doses of vitamin E and C supplements for the sight-robbing condition macular degeneration and that the antioxidants are being studied as treatment for other illnesses. They say "Certainly if there is a risk for other diseases where beta-carotene has been shown to be efficacious, they should still take those."
According to Blumberg, there is a biological basis for vitamin E's potential role in heart disease prevention. He noted that several studies have shown that vitamin E appeared to help prevent heart disease in healthy people who took the antioxidant for over a decade.
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