Clinical Question: Is vitamin E effective in reducing the risk of cardiovascular disease and cancer among healthy women?
Study Design: Randomized controlled trial (double-blinded)
Synopsis: Evidence from observational trials suggests that vitamin E may be effective in preventing cardiovascular disease and cancer in women. In the Women’s Health Study, investigators randomized 39,876 healthy women who were 45 years or older to receive: (1) 600 IU of natural-source vitamin E every other day, (2) placebo and 100 mg of aspirin every other day, or (3) placebo only in a 2 × 2 factorial design. Persons blinded to treatment group assignment assessed outcomes. Follow-up occurred for an average of 10.1 years in more than 97 percent of the patients.
Using intention-to-treat analysis, investigators found that vitamin E did not significantly reduce the risk of major cardiovascular events, including myocardial infarction, ischemic stroke, or hemorrhagic stroke. Although vitamin E slightly reduced the risk of cardiovascular death (number needed to treat for 10.1 years = 586; 95% confidence interval, 306 to 6,058), all-cause mortality was not significantly reduced. Vitamin E did not significantly decrease the risk of any cancer, including breast, lung, and colorectal cancers. Cancer mortality was not significantly lower in any group.
Bottom Line: Vitamin E does not reduce the risk of developing cardiovascular disease or cancer or the rate of total mortality among healthy women 45 years or older. (Level of Evidence: 1b)