In a major cancer prevention study, long-term supplementation with vitamin E or C did not reduce the risk of prostate or other cancers for nearly 15,000 male physicians. This study, along with another cancer prevention study, will be published in the January 7 issue of JAMA, and both reports are being released early online because of public health implications.
In some observational studies, intake or blood levels of vitamins E and C have been associated with reduced risk of certain cancers. “However, definitive proof that vitamins E and C can reduce the risk of overall or site-specific cancers must rely on large-scale randomized trials,” the authors write. “A number of trials have addressed the potential role of vitamins in the prevention of cancer; however, the results from these trials have not been consistent.” Despite uncertainty about the long-term health effects or benefits, more than half of
J. Michael Gaziano, M.D., M.P.H., of Brigham and Women’s Hospital and VA Boston Healthcare System,
During an average follow-up of 8.0 years, there were 1,943 confirmed total cancer cases and 1,008 prostate cancer cases. Compared with placebo, vitamin E had no effect on the incidence of prostate cancer or total cancer. The researchers also found no significant effect of vitamin C on total cancer or prostate cancer. Neither vitamin E nor vitamin C had a significant effect on site-specific cancers, including colorectal, lung, bladder and pancreatic. Stratification by various cancer risk factors demonstrated no significant modification of the effect of vitamin E on prostate cancer risk or either agent on total cancer risk.
“These data provide no support for the use of these supplements in the prevention of cancer in middle-aged and older men,” the authors conclude.