Boston, MA – In a new pooled analysis of nine different studies investigating the effect of vitamin E on stroke, researchers have discovered an association between the use of vitamin E supplements and increased risk for hemorrhagic stroke. These findings are published online in the British Medical Journal on November 5, 2010.
“These findings suggest that the use of vitamin E may not be as safe as we have believed, and is actually associated with some harm – in the form of increased risk for hemorrhagic stroke,” said Markus Schürks, MD, MSc, researcher in the Division of Preventive Medicine at Brigham and Women’s Hospital (BWH) and lead author of the paper. “While the risk is small and translates into one additional hemorrhagic stroke for every 1250 individuals taking vitamin E, we caution against widespread uncontrolled use of vitamin E,” Schürks said.
In the nine controlled, randomized clinical trials that were included in this analysis, there were a total of 118,765 participants with approximately half receiving vitamin E and the remainder receiving placebo. Although none of the results of the individual trials indicated any change in the risk for overall stroke, researchers identified marked differences in risk when evaluating the effect of vitamin E on the two different stroke types, hemorrhagic and ischemic stroke.
Specifically, for ischemic stroke, the researchers found that individuals assigned to receive vitamin E were 10 percent less likely to experience this type of stroke. Analysis showed that among 45,670 participants taking vitamin E, a total of 884 people suffered an ischemic stroke compared to 983 participants who experienced this type of stroke among the 45,733 participants taking placebo. This translates into one ischemic stroke prevented for every 476 individuals taking vitamin E.
For hemorrhagic stroke, researchers found that the participants who took vitamin E were 22 percent more likely to experience this type of stroke. In the analysis, a total of 223 cases of hemorrhagic stroke occurred in the 50,334 participants assigned to vitamin E, and 183 cases of hemorrhagic stroke occurred in the 50,414 participants who received placebo. This can be equated to one additional hemorrhagic stroke for every 1250 individuals taking vitamin E.
“The associations we see in our study are somewhat similar to aspirin, which can lead to a reduction of ischemic stroke but also increased risk of bleeding,” added Tobias Kurth, MD, ScD also affiliated with the Division of Preventive Medicine at BWH and senior author of the study. “Although the effects of vitamin E that are shown in this meta-analysis are both relatively small, hemorrhagic strokes generally have more severe outcomes. Based on these findings, we suggest considering other preventive strategies to reduce the risk of stroke such as a well balanced diet, not smoking, being physically active and maintaining a normal weight.”
Learn more about Brigham and Women’s Stroke and Cerebrovascular Center.