Vitamin E Does Not Appear to Prevent Heart Disease or Cancer in Healthy Women
Cardiovascular disease (e.g., ]]>heart attack]]> , ]]>stroke]]> ) and ]]>cancer]]> are among the leading causes of death throughout the world. For this reason, researchers are constantly looking for strategies to prevent these diseases. One potential strategy, vitamin E supplementation, has shown some promise. However, the majority of studies supporting a beneficial effect for vitamin E have been observational, meaning their results are less convincing than those from clinical trials.
Unstable molecules known as free radicals can damage cells, contributing to the development of cardiovascular disease and cancer. Antioxidant vitamins, including vitamin E, can help protect cells from this damage by eliminating free radicals. Vitamin E is found in vegetable oils, nuts, green leafy vegetables, fortified cereals, and vitamin supplements. Some observational studies in large populations have shown that people who have higher intakes of vitamin E tend to have lower rates of cardiovascular disease and cancer, but other studies have shown no such effect.
New research published in the July 6, 2005 issue of the Journal of the American Medical Association compared women over the age of 45 taking vitamin E supplementation to those taking a placebo in a lengthy clinical trial. The researchers followed the women for 10 years and found no overall benefit associated with vitamin E in protecting against cardiovascular disease or cancer.
About the Study
This study was part of the Women’s Health Study (WHS). It included 39,876 healthy women ages 45 years and older, with no history of cardiovascular, cancer, or other major chronic disease.
The researchers randomly assigned half of the women to receive a moderately high dose (600 international units, or IU) of vitamin E every other day, and the other half to receive a placebo pill.
The researchers followed the women for 10 years and kept track of whether they had major cardiovascular events (heart attack, stroke, or cardiovascular death), developed cancer, or died from any cause. They also recorded any adverse effects associated with the vitamin E supplement or placebo.
During the study, 999 (2.5%) of the women had major cardiovascular events, and 2,865 (7.2%) developed cancer. There was no significant reduction in risk of these conditions in the women who took vitamin E compared to those who took the placebo.
There was, however, a significant 24% reduction in risk of cardiovascular death in women in the vitamin E group. In addition, when the researchers looked at different age groups, they found that there was a significant 26% reduction in major cardiovascular events associated with taking vitamin E versus a placebo in women ages 65 and older.
Taking vitamin E, however, did not affect their overall risk of death. During the study, 636 women in the vitamin E group died, compared with 615 in the placebo group (a nonsignificant difference).
There was no significant increase in risk of adverse events in the vitamin E group. There was, however, a small but nonsignificant increase in risk of nosebleed in the vitamin E group.
It is important to note that these findings do not necessarily apply to men. Recent research showed that low doses of aspirin, for example, affect the risk of heart attack and stroke differently in men and women. The results of the Physicians’ Health Study on the effects of vitamin E in healthy men are expected in late 2008.
How Does This Affect You?
These results suggest that vitamin E supplementation does not confer an overall benefit in decreasing the risk of cardiovascular events or cancer in healthy women ages 45 and older. Women ages 65 and older, however, may benefit from taking vitamin E supplementation, as seen by a 26% reduction in major cardiovascular events associated with vitamin E in this group. While the study did find a decrease in the risk of cardiovascular death associated with vitamin E, the researchers speculate that this finding was most likely due to chance.
These findings are important, since the WHS is the largest randomized trial of vitamin E supplementation, with the longest duration of treatment, to date. Another study published in the same issue of the Journal looked at the same group of women, who were also given alternate day aspirin or placebo. Researchers found that aspirin did not reduce the risk of cancer, with the possible exception of lung cancer, for which aspirin was shown to have a marginally significant effect on the risk of death.
As the author of an accompanying editorial points out, it may be time to conclude that vitamin E supplementation is not beneficial in preventing cardiovascular disease and cancer, at least in healthy women ages 45-64. Considering that vitamin E may not be beneficial and that other trials have suggested it may be harmful (in higher doses), healthy women ought to focus their efforts on healthful lifestyle changes, rather than turning to supplements. Low fat diets diets rich in fresh fruits and vegetables, regular exercise, and smoking cessation are all safe and effective ways of limiting the risk of cardiovascular disease and cancer.
American Cancer Society
American Heart Association
National Cancer Institute
National Heart, Lung, and Blood Institute
Antioxidants: an answer to aging? American Dietetic Association website. Available at: http://www.eatright.org/Public/NutritionInformation/index_2831.cfm . Accessed July 6, 2005.
Cook NR, Lee IM, Gaziano JM, et al. Low-dose aspirin in the primary prevention of cancer: the Women’s Health Study: a randomized controlled trial. JAMA . 2005;294:47-55.
Lee IM, Cook NR, Gaziano JM, et al. Vitamin E in the primary prevention of cardiovascular disease and cancer: the Women’s Health Study: a randomized controlled trial. JAMA . 2005;294:56-65.
Redberg RF. Vitamin E and cardiovascular health: does sex matter? JAMA . 2005;294:107-109
Last reviewed Jul 7, 2005 by ]]>Richard Glickman-Simon, MD]]>
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