January 29, 2005
Doctors Debate Value of Vitamin E
Disagreement over benefits, risks of the antioxidant
HealthDayNews -- Doctors and other health professionals defended on Thursday the safety of vitamin E, and reported on continuing studies that they said show its potential benefits in treating a variety of health problems.
The conference followed the release of a John Hopkins study in November that found elderly, ill patients who took vitamin E daily at doses of 400 International Units (IUs) or more suffered a 6 percent increase in mortality compared to those who took placebos.
One of the criticisms of the Hopkins study expressed by doctors at the conference, sponsored by the supplement industry and held in New York City, was that the conclusions were based on a group of older, ill patients, and these findings aren't necessarily applicable to the general population. The doctors also criticized the statistical method used by the researchers -- called a "meta-analysis." A meta-analysis is the use of statistical methods to combine results of separate studies.
"Meta-analysis is not a great way to do a study because not everyone agrees on the end-point," said Dr. Gerald M. Lemole, chief of cardiac surgery at Christiana Health Care Services in Newark, Del. "Also, you can't say these results apply to the general population."
Dr. Edgar R. Miller, an associate professor of medicine at Johns Hopkins and lead author of the study, defended his statistical methods as the standard way to pool analyses. The study results were representative of those people who most often take vitamin E -- older individuals seeking health benefits and longevity.
"Supplement trials focus on those with disease," Miller said, and people in their 20s, 30s and 40s aren't generally suffering from these illnesses.
"Our study showed a slightly increased risk of mortality, but certainly showed no benefit," he said. "There was a hint, however, which we noted in the study, that in the low dose -- 200 IUs or less -- there was protection," he said. "Maybe we need to reexamine what dose we're giving people."
Ongoing studies have indicated that vitamin E may help to protect against health problems ranging from Alzheimer's disease to cancer to cataracts.
Dr. Mark Moyad, director of Complementary and Alternative Medicine at the University of Michigan, said the study seemed "intended to scare and raise attention." But, he added, "The good news is that it brought out the big issue of dosage."
Moyad, who researches the effects of vitamin E and other vitamins on prostate and bladder cancer, said, "There has to be a risk/benefit ratio -- what dosage and for what condition. People can't pick these vitamin doses at random."
He pointed to a National Cancer Institute study now under way of 32,000 men to test the efficacy of 400 IUs of vitamin E and/or 200 milligrams of the mineral selenium in preventing prostate cancer. This study is a follow-up to earlier studies that showed benefits to taking vitamin E to prevent a recurrence of prostate cancer and decrease in mortality from the disease.
"Vitamin E is going to get objective research to reach an objective conclusion," he said. "You have to stick with the science."
Miller said vitamin E did show benefits in terms of decreasing oxidative stress in cells. But "there's a big gap between that and the bigger and more difficult question is linking these markers to clinical uses, like reducing heart attacks and cancer."
He pointed to approximately 15 NCI trials under way looking into the efficacy of vitamin E. "We should let those studies run their course so we can answer this most definitively," he said.
Other doctors at the conference reported on ongoing, small studies of the efficacy of vitamin E for treating various health problems. Those problems include:
- Alzheimer's disease. Research has shown vitamin E seems to help delay loss of physical function, but has no effect on delaying cognitive damage.
- Cellular damage. A small study found that male participants in marathons had less post-race oxidative stress when they took vitamin E. But women suffered less post-race oxidative stress overall and didn't need the compound.
- Cataracts. Some studies have found that the antioxidant qualities of vitamin E might have a beneficial effect on cataracts.
For more on vitamin E, visit the National Institutes of Health.