Vitamin E increases prostate cancer risk
Sunday, 6 November 2011
The last few days, I’ve blogged several times about prostate cancer screening. While we’re on the topic, I thought you’d be interested in knowing that a major study in the Journal of the American Medical Association shows that taking vitamin E may raise the risk of prostate cancer.
The trial, which involved over 35,000 men, began a decade ago to see if vitamin E and the mineral selenium could prevent prostate cancer. The results were somewhat surprising to me.
In 2008, it was found that neither vitamin E nor selenium prevented cancer and everyone was told to stop taking the vitamins. (see my blog: Are multivitamins helpful or harmful when it comes to preventing chronic diseases?)
Then, in this new study, it was found that men who took vitamin E alone were at a 17% increased risk of developing prostate cancer. But the final verdict on selenium is not in yet.
On its front page, the Washington Post reports, “‘Just because it’s ‘only a vitamin’ or ‘it’s natural,’ we assume it must be safe. But over and over again, we see that’s not necessarily the case,’ said Howard Parnes of the National Cancer Institute. … ‘Not only isn’t it the fountain of youth that some people said, it can be harmful.’”
However, other “scientists and the dietary supplement industry” criticize this study “for trying to evaluate individual vitamins alone, noting the combination of vitamin E and selenium” did not increase risk.
And USA Today says, “The authors say they don’t have an explanation for their findings.” Some, including “urologist Neil Fleshner of Princess Margaret Hospital in Toronto,” believe “the increased risk in the study was ‘just a statistical thing.’”
The Wall Street Journal reports that National Cancer Institute’s Division of Cancer Prevention’s acting director and study co-author Lori Minasian noted that this study used the alpha-tocopherol form of vitamin E, which others suggest is less beneficial than the gamma-tocopherol form. She also said that more research needs to be done on how vitamin E might affect oncogenesis.
The AP quotes the American Cancer Society’s Dr. Otis Brawley, “There should be a global warning that … excessive use of vitamins has not been proven to be beneficial and may be the opposite.”
Bloomberg News reports, “The study ‘is the largest, the most definitive, and the first one to show that there could potentially be harm,’ from regular use of vitamin E, said Leslie Ford, associate director for clinical research at the National Cancer Institute’s cancer prevention division, in an interview.”
The New York Times “Well” blog notes that while vitamins are indeed essential, “in the past few years, several high-quality studies have failed to show that high doses of vitamins, at least in pill form, help prevent chronic disease or prolong life.”
USA Today ‘s “Your Life” blog asked “two top national nutrition experts to weigh in on whether or not consumers should take a multivitamin or other supplements.”
Jeffrey Blumberg of Tufts University said that he recommends multivitamins, but Marion Nestle of New York University said she only recommends “supplements to people with diagnosed nutrient deficiencies” and prefers that people eat a nutritious, balanced diet.
ABC News points out on its website, “Two previous studies … reached different conclusions on how vitamin E affects prostate cancer. In 2003, data from the Alpha-Tocopherol, Beta-Carotene Cancer Prevention) trial showed that smokers taking 50 mg of vitamin E each day had a 35 percent reduction in prostate cancer. In the Physicians Health Study II, participants took the same amount of vitamin E as the men in the Select trial – 400 IU, but it had no effect on their risk of prostate cancer.”
HealthDay reports, “Because more than 50 percent of men 60 and older take supplements containing vitamin E and 23 percent take as much as 400 international units (IU) a day despite the recommended daily dietary allowance of only 22.4 IU, the implications of this finding are ‘substantial,’ the study authors said.”
What’s the bottom line?
If you’re taking vitamin E to prevent prostate cancer, you may want to consider stopping.