Vitamin E Harms More Than It Helps
Supplement No Help for Cancer, Heart, Stroke -- but Increases Heart Failure Risk
March 15, 2005 -- Vitamin E harms more than it helps, a large study shows.
Vitamin E is a powerful antioxidant, thought to clear the body of harmful oxygen compounds called free radicals. By soaking up free radicals, researchers hoped that vitamin E would prevent cancer and heart disease.
That doesn't happen, finds Eva Lonn, MD, of McMaster University in Hamilton, Ontario, and colleagues. Lonn led a seven-year-long, international study that enrolled thousands of people at high risk of heart disease. The findings added to suspicions raised by prior studies: Vitamin E isn't worth it.
"We saw definitely no benefit, and at least the potential for harm," Lonn tells WebMD. "Now the overwhelming evidence from many studies is that vitamin E provides no protection against heart disease, stroke, or cancer."
Lott and colleagues report their findings in the March 16 issue of The Journal of the American Medical Association.
Vitamin E Harm: Slight but Significant Risk
Lonn's study enrolled nearly 10,000 people with heart disease, peripheral artery disease (also commonly called poor circulation, a disease of blood flow through the arteries) or diabetes. This put them at very high risk of heart attack and stroke. All were over age 55. Half got high-dose vitamin E -- 400 IU every day (about 400 milligrams) -- and half got fake pills that looked the just the same.
After four years, those who took vitamin E had no fewer heart attacks, strokes, cancers, or cancer deaths.
But many experts wondered whether that was long enough for vitamin E to help. So Lonn and colleagues extended the study for another three years.
"But we saw no benefit at all on cancer and no benefits for heart outcomes -- a composite measure of heart attack, stroke, and heart death," Lonn says.
Unexpectedly, they did see one difference. Patients taking vitamin E had significantly more heart failure.
Vitamin E was linked to a 13% higher risk of heart failure and a 21% increased risk of hospitalization for heart failure. That's a pretty small risk. But since the vitamin did no good at all, it's a risk not worth taking.
"If there is no benefit from taking something, you shouldn't take even a small risk of harm," Lonn says.
There is no need to worry if you take a multivitamin that contains recommended amounts of vitamin E. But Lonn advises people not to take pills containing high amounts (400 IU or more) of vitamin E.
Is Vitamin E Dead?
B. Greg Brown, MD, PhD, head of the atherosclerosis research lab at the University of Washington School of Medicine, was one of the first scientists to suggest that vitamin E and other antioxidant vitamins may not work the way they were supposed to.
"Vitamin E has been very clearly shown to be of no benefit to the general problem of cancer or heart disease," Brown says. "Studies are still looking at whether vitamin E can help prostate cancer, [mouth and throat] cancer, and severe macular degeneration. But all in all, there is relatively little hope for a major effect. There's not a lot of hope for vitamin E. It's proven to be without benefit."
Brown's editorial accompanies the Lott study in the March 16 issue of JAMA.