Vitamins E and C and selenium 'do not protect against cancer'
Two new studies in the Journal of the American Medical Association have found that people who supplement their diet with vitamins E and C or the mineral selenium do not have a lower risk of cancer.
The Physicians Health Study II concluded that neither vitamin E nor vitamin C supplements reduced the risk of prostate cancer or the overall risk of cancer in middle-aged or older men, while the Selenium and Vitamin E Cancer Prevention Trial (SELECT) found that selenium and vitamin E did not prevent prostate cancer.
The first study involved 14,641 doctors who were at least 50 years old at the start of the trial and who were given 400 IU of vitamin E or a placebo (dummy pill) every other day, or 500 mg of vitamin C or a placebo every day.
After ten years of follow-up, the researchers found that people who had taken vitamin E were no less likely to develop prostate cancer than those who took a placebo. There was also no significant difference in their overall cancer risk.
Vitamin C also had no significant effect.
Dr Howard Sesso, assistant professor of medicine at Brigham and Women's Hospital, commented: "After nearly ten years of supplementation with either vitamin E or vitamin C, we found no evidence supporting the use of either supplement in the prevention of cancer.
"While vitamin E and C supplement use did not produce any protective benefits, they also did not cause any harm," he noted.
Study co-author J Michael Gaziano, associate professor of medicine at Brigham and Women's Hospital, added: "Individual vitamin supplements such as vitamin E and C do not appear to provide the same potential advantages as vitamins included as part of a healthy, balanced diet."
The second study, SELECT, was stopped by the National Cancer Institute in October 2008 after vitamin E and selenium failed to help prevent prostate cancer.
The trial started in 2001, with more than 35,000 men divided into four study groups. One group took selenium and vitamin E; the second took selenium and a vitamin E placebo; the third received vitamin E and a selenium placebo; and the final group received placebos of both supplements.
Neither supplement was found to reduce the risk of prostate cancer, and the researchers even noted a very small increase among over-50s who took vitamin E alone, although the increase was not significant and may simply have been due to chance.
Dr Jodie Moffat, health information officer at Cancer Research UK, said: "There are a lot of studies looking at whether vitamin and mineral supplements can reduce the risk of cancer but many of them, like this one, don't support a link. This new research means it is even less likely than we previously thought that supplements can protect against prostate cancer.
"Supplements don't substitute for a healthy diet and some studies have shown that they may actually increase the risk of cancer. Eating a diet that is high in all types of fruit and vegetables is the best way to get the vitamins and minerals that we need."
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