Long-term supplementation with vitamin E or C did not reduce the risk of prostate or other cancers for nearly 15,000 male physicians.

The 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 U.S. adults take vitamin supplements, and vitamins E and C are among the most popular individual supplements, according to background information in the article.

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.

“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. 

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