Nov. 5, 2010 -- Although the risk remains relatively small, researchers have found that taking vitamin Esupplements increases the risk of hemorrhagic stroke, in which bleeding occurs in the brain. But vitamin E supplements reduce the risk of ischemic stroke, the more common type of stroke, in which blood flow to the brain is blocked, the researchers say.
Markus Schürks, MD, a researcher at Brigham and Women’s Hospital in Boston, led an international team that analyzed data from the medical literature. The group reviewed nine trials published through January 2010 that included more than 118,000 study participants; 59,357 took vitamin E supplements and 59,408 took a placebo. The trials did not include people who took multivitamins.
Vitamin E did not significantly affect the risk of stroke overall. The study did not evaluate which doses of vitamin E produced which outcomes. Instead, it looked at any association between vitamin E use and stroke. When looking at different types of stroke, researchers found that:
Taking vitamin E supplements increased the risk of hemorrhagic stroke by 22% but reduced the risk of ischemic stroke by 10%.
A total of 223 hemorrhagic strokes occurred among 50,334 who took vitamin E supplements, whereas 183 hemorrhagic strokes occurred among those taking a placebo.
A total of 884 ischemic strokes occurred among 45,670 people taking vitamin E supplements, whereas 983 ischemic strokes occurred among 45,733 people taking a placebo.
The authors estimate that based on this data, there could be one additional hemorrhagic stroke for every 1,250 people taking vitamin E, whereas one ischemic stroke would be prevented per every 476 people taking vitamin E.
The findings are published in today’s online edition of BMJ.
“Given the relatively small risk reduction of ischemic stroke and the generally more severe outcome of hemorrhagic stroke, indiscriminate widespread use of vitamin E should be cautioned against,” the authors write.
Previous studies had suggested vitamin E supplements may reduce cardiovascular disease, but other studies have indicated that taking high doses of vitamin E might increase the risk of death. An estimated 12.7% of the U.S. population takes vitamin E supplements, according to the report.
Stroke is the third leading cause of death in the U.S., after heart disease and cancer, according to the American Heart Association. Stroke kills more than 137,000 people every year in the U.S. and accounts for one out of every 18 deaths. Sixty percent of stroke deaths occur among women.