Vitamin C Or E Supplementation Not Associated With Reduced Risk Of Prostate Or Other Cancers

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Main Category: Cancer / Oncology
Also Included In: Nutrition / Diet;  Clinical Trials / Drug Trials;  Public Health
Article Date: 10 Dec 2008 - 0:00 PDT

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Long-term supplementation with either vitamin E or vitamin C does not appear to reduce the risk of prostate cancer or other cancers, according to a study released on early December 9, 2008 Online in JAMA. This will be published on January 7, 2008, but has been released early due to the great implications in public health.

More than half of adults in the United States take vitamin supplements, despite conflicting results about their effectiveness in prevention of certain diseases, according to the background information in the article. Previously, many observational studies (rather than randomized) have shown that either additional intake of or higher blood levels of vitamins E and C are associated with a reduced risk of certain cancers. The authors note that, since observational studies are often affected by confounding influences, "definitive proof that vitamins E and C can reduce the risk of overall or site-specific cancers must rely on large-scale randomized trials." They continue: "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."

To investigate the independent effects of these vitamins on cancer risk, J. Michael Gaziano, M.D., M.P.H., of Brigham and Women's Hospital and VA Boston Healthcare System, Boston, and colleagues conducted the Physicians' Health Study II, a randomized controlled trial consisting of 14,641 male physicians in the United States above the age of 50. To examine prostate cancer, the study excluded 1,307 with prior cancer history. Each participant was randomized to receive vitamin E supplements every other day or placebo and randomized to receive vitamin C daily or a placebo.

With an average follow-up period of 8.0 years, the researchers confirmed 1,943 total cases of cancer, with 1,008 of these cancers of the prostate. In comparison with the placebo, vitamin E supplementation did not affect either prostate cancer or all types of cancer. This was true for vitamin C as well. Neither was shown to have an effect on any of the examined site-specific cancers, including colorectal, lung, bladder and pancreatic cancers. This was true even after stratification by various confounding factors.

The authors conclude with a strong statement about the effectiveness of these vitamins in cancer prevention in this population: "These data provide no support for the use of these supplements in the prevention of cancer in middle-aged and older men."

Vitamins E and C in the Prevention of Prostate and Total Cancer in Men: The Physicians' Health Study II Randomized Controlled Trial
J. Michael Gaziano, MD, MPH; Robert J. Glynn, ScD; William G. Christen, ScD; Tobias Kurth, MD, ScD; Charlene Belanger, MA; Jean MacFadyen, BA; Vadim Bubes, PhD; JoAnn E. Manson, MD, DrPH; Howard D. Sesso, ScD, MPH; Julie E. Buring, ScD
JAMA. 2009;301(1)
doi:10.1001/jama.2008.862
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Written by Anna Sophia McKenney
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