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Vitamin E and strokes
Posted by medconsumers on November 19, 2010
Remember when vitamin E was the fad supplement of the moment? High doses were supposed to prevent everything from heart disease to cancer. That was the 1980s. Then a study showed high doses of vitamin E increased the risk of death in smokers. In time, enthusiasm cooled for all antioxidants (vitamins E, A, and beta carotene) when a 2008 Cochrane review of all placebo-controlled trials found no preventive benefit and a slight increase in mortality. Last year the American Journal of Epidemiology published a study with this contradictory finding: Six years of taking vitamin E supplements decreased mortality by 41% in elderly male smokers who had high dietary vitamin C intake, but increased mortality by 19% in middle-aged smokers who had high dietary vitamin C intake.
This week a new study in the British Medical Journal shows the latest in contradictory study results: High doses of vitamin E supplements will decrease the risk of one type of stroke but increase the chance of having another. The finding is based an analysis of nine trials, conducted by an international team of researchers led by Markus Schurks, Harvard Medical School.
Vitamin E increased the risk for hemorrhagic stroke by 22% and reduced the risk of ischemic stroke by 10%. The latter stroke is caused by blockage in an artery that supplies blood to the brain, resulting in a deficiency in blood flow (ischemia). Hemorrhagic stroke is caused by the bleeding of ruptured blood vessels (hemorrhage) in the brain.
I particularly like the fact that Schurks and colleagues also put their results in the more understandable, absolute risk terms. There will be “one additional hemorrhagic stroke for every 1250 individuals taking vitamin E, in contrast to one ischemic stroke prevented per 476 individuals taking vitamine E.” Their conclusion: “Given the relatively small risk of ischemic stroke and the generally more severe outcome of hemorrhagic stroke, indiscriminate widespread use of vitamin E should be cautioned against.”
The nine trials had a combined total of 118,765 participants, ages 40 to 75 years. Most were healthy at the start of the trials, though many were at high risk for cardiovascular disease (e.g. smokers). Virtually all participants had been randomly assigned to take vitamin E supplements or a placebo. There was a wide range of daily doses in these trials—from 50 mg (synthetic) to 800 IU (natural). The vitamin E daily recommendations issued by U.S. Office of Dietary Supplements are 15 mg (22.4 IU).
Years ago I, too, was a big fan of high-dose vitamin E because a study or two backed it up. Even took a daily multivitamin for many years…that is, until I read a 2006 National Institutes of Health State-of-the-Science report. Though a poster child for the woman destined to break her hip, I was never convinced about the long-standing dictum about high-dose calcium. And now that even this sacred cow has been thrown overboard (See “Rethinking calcium”), vitamin D is the only supplement left in my kitchen cabinet. I suppose it’s only a matter of time…
Addendum: Eleven days after this article was posted, The New York Times carried this front-page article about a new report from the Institute of Medicine, which questioned the need for high doses of calcium and vitamin D (click here).
Maryann Napoli, Center for Medical Consumers©
4 Responses to “Vitamin E and strokes”
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JonathanR said
I found the vitamin D recommendations a little perplexing (although I was pleasantly surprised to see that they had indeed gone up). True, I think people using supplements don’t use them judiciously enough and don’t think long and hard about why they are taking them, but the daily D values still seem low. Only because it’s “normal” for people to spend some time outdoors during mid-day sun peaks. And since science has shown that only a few minutes a day of early-afternoon sun exposure prompts the synthesis of thousands of IUs of D, supplementing seems warranted for those of us either stuck indoors or in the Northeast who deal with these crappu, sunless winters.
Ann Fonfa said
Sorry all, I typed this up and then it got ‘lost’ in computerland somewhere. Now I feel that at least one reference is missing, but here are some:
Dietary alpha-Tocopherol Decreases alpha-Tocotrienol but Not gamma-Tocotrienol Concentration in Rats.
J Nutr 2003 Feb;133(2):428-34 Ikeda S, Tohyama T, Yoshimura H, Hamamura K, Abe K, Yamashita K
alpha-Tocopherol and Ascorbic Acid Decrease the Production of ß-Apo-carotenals and Increase the Formation of Retinoids from ß-Carotene in the Lung Tissues of Cigarette Smoke–Exposed Ferrets In Vitro1
J. Nutr. 134:426-430, February 2004 Chun Liu, Robert M. Russell and Xiang-Dong Wang2
Nutrition and Cancer 1999, Weiping Yu, Macha Simmons-Menchaca et al
“It is important to note that when vitamin E compounds are considered for possible therapeutic applications, not only does the form of vitamin E need to be carefully considered but the possibility that RRR-alpha-tocopherol may ameliorate or block tocotrienol and VES-mediated effects needs to be taken into account”.[12,47] SORRY, at the http://Annieappleseedproject.org, we neglected to save the volume number or issue for this 1999 citation.
Ann Fonfa said
We now know that vit E is not just d-alpha tocopherol (or the synthetic dl-alpha tocopherol. It seems that the other aspects of vit E are needed for good health. Why do trialists continue to just give d-alpha or dl-alpha? That is problematic for good results.
medconsumers said
Please post a citation for your statement: “other aspects of vit E are needed for good health,” as well as for evidence of safety when “these other aspects of vit E” are taken in high doses as supplements.