"This just shows us once again that very high level of individual nutrients can have adverse effects," said Alice H. Lichtenstein, a professor of nutrition at Tufts University who chairs the nutrition committee of the American Heart Association, which in August issued an advisory against taking antioxidant supplements to reduce the risk of heart disease.
Other researchers, however, questioned the new findings, saying the analysis was flawed and that other studies have shown a benefit from taking Vitamin E and other antioxidants.
FDA Unveils New Rules For Supplement Labels (The Washington Post, Nov 5, 2004)
Antioxidant Pills Questioned, Again (The Washington Post, Oct 12, 2004)
Deep Purple (The Washington Post, Oct 6, 2004)
Overfed, Undernourished (The Washington Post, Sep 21, 2004)
Accept No Substitutes (The Washington Post, Aug 25, 2004)
"There is a small statistical effect here that they have found, but we don't believe it's necessarily an important biological effect," said Annette Dickinson, president of the Council for Responsible Nutrition, an industry-funded group. "We think they've overstated the importance of the findings."
Maret G. Traber, an Oregon State University researcher who served on a National Academy of Sciences panel that evaluated Vitamin E, agreed. "Vitamin E won't kill you," Traber said. "Everything we know about Vitamin E is that it's incredibly safe."
While there is only weak evidence that antioxidants reduce the risk of cancer, there is strong evidence that Vitamin E and Vitamin C can reduce the risk of heart and kidney disease, said Ishwarlal Jialal, an antioxidant researcher at the University of California at Davis.
"Vitamin E is clearly an antioxidant and an anti-inflammatory agent, and it's been shown in some studies to reduce heart disease either alone or in combination with Vitamin C," he said.
The latest study, however, found that the overall death rate appeared to increase beginning with people taking 400 international units per day, Miller and his colleagues reported in a paper that will be published in the Jan. 4, 2005, issue of the Annals of Internal Medicine. They reached that conclusion by reanalyzing data collected by 19 studies conducted between 1993 and 2004 involving a total of 135,967 patients in North America, Europe and China using a technique known as meta-analysis.
On average, people get about 10 international units of Vitamin E from diet, primarily from consuming foods such as corn, nuts, seeds, olives, asparagus, spinach, other leafy green vegetables, and vegetable oils. But Vitamin E supplement capsules contain anywhere from about 400 to 800 international units.
Federal nutritional guidelines do not recommend Vitamin E supplementation but state that doses as high as 1,000 international units per day are safe. Based on the findings, Miller and his colleagues recommended the upper limits be reevaluated.
"Certainly there's no benefits to high-dose Vitamin E intake, and we did demonstrate harm, so we're not recommending people take high-dose Vitamin E supplementation," Miller said.