Vitamin E - good or bad for strokes?

  • 10 Nov 2010
  • Reading time 3 mins
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A recent analysis in the British Medical Journal suggests that vitamin E reduces the common kind of 'ischaemic' stroke but increases risk of the rarer 'hemorrhagic' stroke. If you take vitamin E should you be concerned?

I contacted Dr Maret Traber, the vitamin E expert at the Linus Pauling Institute who knows more about vitamin E than anyone for her comment on this study and this is what she says: “The authors highlight both the strengths and limitations of their analysis. Strengths include a large sample size from high quality randomised controlled studies (RCTs) and inclusion of studies that are combinable (i.e. similar design).

Some of the limitations include most of the data were derived from studies involving diseased or high risk patients, so the results may not be relevant to the general population. The authors focused solely on stroke outcomes, not addressing other cardiovascular outcomes and other health outcomes. Several individual vitamin E RCTs have shown benefits from supplemental vitamin E on other cardiovascular outcomes beyond stroke, including the Women’s Health Study (WHS) and the Women’s Antioxidant Cardiovascular Study (WACS).

Supplemental vitamin E may also provide benefits beyond cardiovascular events, including immune function and eye health. This meta-analysis did not address these other important and relevant outcomes. This analysis only examined RCTs involving supplemental vitamin E alone. We know that antioxidants (and indeed all nutrients) don’t function in isolation but as part of complex networks, so the idea that a single nutrient, supplemented at high doses in primarily cardiovascular patients or smokers, will have potent effects may be misplaced to begin with. Even though many studies (including those examined in this analysis) show benefits of supplemental vitamin E, it may be wiser to examine vitamin E’s effects in the context of the full antioxidant network, rather than in isolation.

The authors also acknowledge that, although the relative risk numbers appear high (22% increase for hemorrhagic and 10% decrease for ischemic, respectively), the absolute effects are quite small and may be somewhat misleading, placing in question the clinical relevance of this report. Based on their analysis, the authors estimate that for every 1000 patients exposed to vitamin E they would predict 0.8 more hemorrhagic strokes and 2.1 fewer ischemic strokes. So the benefits may actually outweigh the risks, when it comes to stroke." There are two other points worth bearing in mind. We know that statin drugs, widely prescribed to those with cardiovascular risk, knock out Co-enzyme Q10, which is needed for vitamin E to function as an antioxidant.

There is no way of knowing what percentage of people in these trials where taking both statins and high dose vitamin E, which I never recommend UNLESS you are also supplementing 90mg of CoQ10. Also, vitamin E has antiatherosclerotic and antiplatelet effects that may reduce the rate of ischemic stroke. On the other hand, vitamin E exerts an anticoagulant effect via inhibition of vitamin K-dependent clotting-factors activation. If a person were both on blood thinning drugs, especially warfarin, and high dose vitamin E, maybe this is too much thinning. As I say in my book Food is Better Medicine than Drugs which has a whole strategy for cardiovascular disease prevention and treatment, it is wise to limit vitamin E if you are on these drugs. Also, most people are not achieving even basic levels of vitamin E. In reality, supplementing 100 or 200mg of vitamin E is likely to confer protection. That's what I take daily.