Vitamin E supplements, taken by many Americans in hopes of warding off heart disease, do not work, and may actually make the condition worse, researchers say.
"People take vitamin E because they think it's going to make them live longer. This doesn't support that at all," said Dr. Edgar Miller of Johns Hopkins University, who led the new analysis.
The study was reported Wednesday at an American Heart Association conference in New Orleans and was also published online by the Annals of Internal Medicine.
Many Americans continue to take vitamin E despite Heart Association guidelines saying it doesn't work and recent research suggesting it can interfere with statin drugs.
The study was an analysis of 19 previous studies involving a total of about 136,000 people who took vitamin E alone or in combination with other vitamins.
Those taking 400 international units per day or more, the amount in most vitamin E supplements, were 10 percent more likely to die than those taking 200 units or less.
Most multivitamins contain 35 to 40 units of vitamin E, which the study suggests might be slightly beneficial for health, Miller said.
"I spend all my time trying to tell patients why they should not take vitamin E," Dr. Raymond Gibbons, a Mayo Clinic cardiologist and chairman of the American Heart Association conference. "Too often in terms of the supplements there's very scant science. In this area, we have the science. Vitamin E doesn't work."
The idea that antioxidants such as vitamin E might ward off heart trouble was based in part on test tube studies that indicated they protect the heart's arteries by blocking the damaging effects of oxygen. Studies also show that healthy people who eat vitamin-rich food seem to have less heart disease.
However, experts say that perhaps antioxidants work when only in food, or that people who eat vitamin-rich food have a lower risk of heart disease because they take better care of themselves overall.
Dr. Robert Eckel, a cardiologist and metabolism expert from the University of Colorado Health Sciences Center, said he long has advised patients not to take vitamin E but that people cling to the belief it is beneficial. One woman he recently treated was taking 23 nutritional supplements but did not want to take "medicines" because she thought all supplements were good and all prescription drugs suspect.
This is a real issue," he said.