Too Much Vitamin E Might Increase Heart Failure Risks
Study shows no benefit in high doses of the antioxidant, and a possibility of harm to the vascular systemMar 16, 2005 | Newsday
People who take high doses of vitamin E with hopes that it may protect against heart disease and cancer may want to reconsider. A seven-year study following thousands of people over 55 found that the antioxidant offered no health benefits, and could, in some cases, increase the risk of heart failure.
"It made great biological sense," Dr. Edgar Miller, an associate professor of medicine at Johns Hopkins University in Baltimore, said of the belief in the vitamin's protective effect. "But this study, and many other large trials, have concluded that there is no benefit, despite the great hope."
Last year, Miller and colleagues published an analysis of 19 clinical trials that found people who took high doses seemed to die sooner.
The latest study, in the Journal of the American Medical Association, recruited more than 9,000 people in the 1990s and followed them for seven years. Virtually all had heart disease or other medical conditions, but not heart failure, a chronic condition characterized by the weakened heart's inability to adequately circulate blood. They were given either a placebo or 400 milligrams of vitamin E more than 20 times higher than the daily dose recommended by the federal government, which is around 15 milligrams.
"There was no benefit for cardiovascular disease or cancer," said Dr. Eva Lonn of the Population Health Research Institute and McMaster University in Ontario. "There is even a possibility of harm," she added. Those taking high-dose vitamin E had a 19 percent increase in incidence of serious heart failure compared with those on placebo an unexpected and unexplained finding.
"Unfortunately, there is no magic pill, or vitamin, to prevent heart disease," Lonn said.
The hope of vitamin E in the prevention of medical illness was based on its powers in the laboratory. It has strong antioxidant effects, and oxidation has been linked to heart disease and the abnormal cell growth that triggers cancer.
In recent years, study after study has shown high-dose vitamin E is useless, Lonn said.
But this is probably not the end for vitamin E, researchers say. Prevention studies on dementia are under way, as are studies of vitamin E for prevention of prostate cancer and age-related macular degeneration.
"I wouldn't go out and wave banners telling people to stop taking vitamin E," said Dr. C. Wayne Callaway, the former head of the lipid and nutrition program at the Mayo Clinic. "The people they selected were already sick. People should be given options if some studies have shown a benefit."
The best choice, said Catherine Loria, a nutritional epidemiologist at the National Heart, Lung and Blood Institute, is to eat a well-balanced diet, which can include a multivitamin. She said that the average American consumes 7 to 8 milligrams a day through oils, vegetables, seeds and nuts. A multivitamin can double intake.