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 and the decreased risk for ischemic stroke.
Markus Schrks, MD, MSc, researcher in the Division of Preventive Medicine at Brigham and Women's Hospital (BWH) and lead author of the paper said the risk for hemorrhagic stroke due to vitamin E is small -- about one in 1250 people -- but those taking the supplement should be careful.
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."
