TUESDAY, March 15, 2005 (HealthDay News) -- Vitamin E doesn't help prevent cancer or cardiovascular disease and can, in fact, increase the risk of heart failure.
That's the conclusion of an extended trial of thousands of older people with a history of cardiovascular disease or diabetes who were randomly assigned to take either 400 I.U. of vitamin E or a placebo.
The results, published in the March 16 issue of the Journal of the American Medical Association, found there was up to a 19 percent increase in the risk of heart failure in the study volunteers who took vitamin E compared to those on the placebo.
"I don't think people have to panic" if they've been taking vitamin E, said study author Dr. Eva Lonn, a professor of medicine at the Population Health Research Institute at McMaster University in Hamilton, Ontario, Canada.
She noted that the incidence of heart failure was lower in study participants than the incidence of either heart attack or stroke. And it's also possible the findings were simply due to chance, because so far other studies haven't shown this side effect, Lonn said. Still, she added, most other studies haven't looked specifically for heart failure, either.
In younger, healthier people, Lonn said, vitamin E is probably safe, "but I think it would be a waste of time." She said numerous studies, including hers, have found no protective effect from vitamin E against heart disease or cancer.
At least one expert from the dietary supplement industry disagrees with Lonn, however.
"This study is not the final word," said Annette Dickinson, president of the Council for Responsible Nutrition, a trade association representing the dietary supplement industry. "This was a study done on older people with serious preexisting disease, taking a number of medications, and their findings have not been confirmed in other studies."
"I think that healthy people can still be confident in vitamin E," Dickinson added. "A number of studies have shown benefits in some types of cancers, eye diseases, and neurological conditions, such as Alzheimer's."
The new study is a continuation of the Heart Outcomes Prevention Evaluation (HOPE) trial, which included data on 9,541 people who were over 55 and either had a history of heart disease or diabetes. The original study was conducted from December 1993 through April 1999. Results of that study were published in the New England Journal of Medicine in 2000. Study volunteers were randomly chosen to receive either 400 I.U. daily of vitamin E or a placebo.
Lonn said many researchers felt the original trial was conducted for too short a period of time. It was suggested that if vitamin E were going to show a benefit, it would likely come from long-term use.
So, Lonn and her colleagues extended the trial from April 1999 through May 2003. This second arm of the trial was dubbed HOPE -- The Ongoing Outcomes (HOPE-TOO). Almost 4,000 people from the original study consented to continuing in the extended study. The researchers were also able to obtain follow-up information through medical records for many people who didn't stay in the study.
HOPE-TOO found no evidence that vitamin E protects against cancer or cardiovascular disease. In fact, the researchers found that the rate of heart failure increased in people taking vitamin E.
Lonn said the overall increase in heart failure risk was 13 percent. For heart failure requiring hospitalization, the risk was increased by 19 percent in the vitamin E group, she said.
While Lonn said the mechanism that might cause vitamin E to increase the risk of heart failure isn't clear, it may be that in the presence of oxidative stress, vitamin E may act as a pro-oxidant, rather than an antioxidant.
But, again, Lonn said she doesn't think anyone who's been taking vitamin E needs to worry. Her biggest concern, she said, is that many people who take vitamins and other dietary supplements may think they don't need to take other steps to prevent cancer and heart disease, such as getting enough exercise and eating right.
Dickinson said, "There needs to be more evaluation of these findings. I agree that it's a good idea to examine those results, but I think it's likely to show it's a chance finding."
"I think that for healthy people, that there's no indication that vitamin E isn't safe when taking 400 I.U. a day," she said.
More information
To learn more about vitamin E, visit the National Institutes of Health's Office of Dietary Supplements.
