I understand your concern. Here's the story: results of a new analysis from Johns Hopkins University suggest that taking daily doses of vitamin E that exceed 400 international units (IU) can increase the risk of death. The researchers arrived at their conclusion after analyzing death rates in 19 unrelated clinical trials that studied vitamin E supplementation for various health conditions. The trials took place from 1993 to 2004 and all together included more than 136,000 patients in North America, Europe and China. The vitamin E doses used in the different trials ranged from 15 to 2000 IU per day; the average daily intake was about 400 IU.
The technique used to arrive at the Hopkins' results - called meta-analysis - can only raise questions, not answer them. Vitamin E has no known toxicity, except for an anticoagulant effect that is usually desirable.
The analysis found that taking a daily dose of 200 IU per day presented no increased risk of death and suggested that it might benefit health. However, the researchers found an increased risk of death at daily doses exceeding 200 IU; for those taking daily doses of 400 IU or more the risk of death was about 10 percent higher than among those taking placebos.
But the analysis also revealed some seemingly contradictory data. For example, one of the studies showed that among people who had had a heart attack, taking vitamin E was correlated with a lower risk of a second heart attack. Despite this encouraging finding, the patients taking the vitamin E were more likely to die than those taking the placebo.
It is important to know that most of the patients in all of the trials analyzed were over 60 and had pre-existing health problems such as heart or kidney disease. The Hopkins researchers conceded that because of the age and compromised health of the study participants, their findings might not apply to younger, healthier people. The study results were presented on Nov. 10, 2004, at the American Heart Association's Scientific Sessions in New Orleans. They were simultaneously released on the Web site of the Annals of Internal Medicine.
My feeling is that the health status of the study participants could be the problem here - perhaps the vitamin E had some unpredictable bad effect on their pre-existing conditions or didn't mix well with certain medications. The researchers also may have overlooked controlling for the form of vitamin E used in the various studies. Natural vitamin E in the form of mixed tocopherols can possibly provide different benefits than synthetic versions limited to alpha tocopherol. We've seen in the past that under certain circumstances supplements can have unexpected, negative effects. For example, two major studies have shown that straight beta carotene supplements led to more, not less, lung cancer among smokers.
Based on what we know now, my advice is still to take supplemental vitamin E in doses up to 400 IU a day but not exceeding that. Avoid dl-alpha-tocopherol and look for products that include all four tocopherols, not just the d-alpha form. Better yet, try to get the whole vitamin E complex: four tocopherols plus four tocotrienols. But, as always, be sure to discuss with your physician any supplements and medications you take - over the counter or otherwise.
Andrew Weil, MD