THURSDAY, Nov. 4, 2010 (HealthDay News) -- People who take vitamin E supplements may be putting themselves at a slight increased risk for a hemorrhagic stroke, researchers report.
Some studies have suggested that taking vitamin E can protect against heart disease, while others have found that, in high doses, it might increase the risk of death. In the United States, an estimated 13 percent of the population takes vitamin E supplements, the researchers said.
"Vitamin E supplementation is not as safe as we may like to believe," said lead researcher Dr. Markus Schurks, who's with the division of preventive medicine at Brigham and Women's Hospital in Boston.
"Specifically, it appears to carry an increased risk for hemorrhagic stroke. While the risk is low translating into one additional hemorrhage per 1,250 persons taking vitamin E, widespread and uncontrolled use of vitamin E should be cautioned against," he added.
The report is published in the Nov. 5 online edition of the BMJ.
For the study, Schurks and his colleagues did a meta-analysis, which is a review of published studies, that looked at vitamin E and the risk for stroke.
There are basically two types of stroke: one where blood flow to the brain is blocked, called an ischemic stroke, and one where vessels rupture and bleed into the brain, called a hemorrhagic stroke. Of the two, hemorrhagic strokes are more rare, but more serious, the researchers noted.
The research team looked at nine trials that included 118,756 patients. Although none of the trials found an overall risk for stroke associated with vitamin E, there was a difference in the risk of the type of stroke.
The researchers found there were 223 hemorrhagic strokes among the 50,334 people taking vitamin E, compared with 183 hemorrhagic strokes among the 50,414 people taking a placebo. That's a 22 percent increase in hemorrhagic stroke risk among vitamin E users, Schurks's group noted.
However, for the risk of ischemic stroke, vitamin E was actually mildly protective, reducing the risk of ischemic stroke 10 percent, the researchers found.
Schurks said the absolute risk of having a hemorrhagic stroke linked to vitamin E is small -- one additional hemorrhagic stroke for every 1,250 people taking the supplement.
Vitamin E may prevent one ischemic stroke in 476 people taking the supplement, the researchers added.
The researchers stressed that other ways of reducing the risk of strokes -- such as lowering blood pressure, taking cholesterol-lowering drugs and living a healthy lifestyle -- have much more impact on preventing ischemic stroke than vitamin E.
Dr. Larry B. Goldstein, director of the Duke University Stroke Center, said that "in addition to the studies included in this analysis, a large randomized trial of a combination of antioxidant vitamins, including vitamin E, in patients with vascular disease or diabetes found no effect on vascular events, including stroke, despite a significant increase in blood levels of the vitamins."
There's also some data suggesting that antioxidant vitamins might interfere with the effects of statin medications used to lower cholesterol levels in patients with vascular disease, he said.
"As there is no evidence of benefit and at least the possibility of harm, these vitamin supplements should generally be avoided, or at least their use should be discussed with a physician if being taken for a specific medical condition," Goldstein said.
For more information on stroke, visit the U.S. National Library of Medicine.