New results published online today from the Physicians’ Health Study II (PHS II), showed that participants who took a daily multivitamin for 11 years had 8 percent fewer cancers compared to participants who took a daily placebo. The study is a large randomized controlled trial involving over 14,600 male physicians aged 50 and over.
The study is published in the Journal of the American Medical Association.
Though the reduction in incidence is relatively small, it is significant, and the PHS II is a large, rigorous and well-respected double-blinded randomized trial. (In the study, one group took a multivitamin and one group took a placebo; neither the subjects nor the doctors knew which was which.) Continue reading
If AICR Blog readers represent the US population, almost half of you will reach for a nutritional supplement at some point today. But if you’re taking that supplement to reduce cancer risk, be aware the evidence just doesn’t support that link. And you should have more guidance from government regulators telling you that, argues a commentary published yesterday in the Journal of the National Cancer Institute.
In the commentary, the authors reviewed the evidence linking cancer risk to several popular supplements, including vitamin D, beta-carotene and folic acid.
As the authors point out, AICR is among an impressive list of health organization who have reached the same conclusion: there is not yet enough evidence to say that nutritional or phytochemical supplements prevent against cancer.
You can read the abstract of the commentary here.
When studies are continuously finding evidence of how a vitamin, mineral or phytonutrient can help our health, it’s tempting to assume more is better. But no, suggests a growing body of evidence. The past few days have seen a flurry of studies on the possible harms linked to supplements, with one of the largest focused on cancer.
The new cancer-supplement study looked at vitamin E and selenium’s link to prostate cancer.
Years ago, researchers hypothesized that these two supplements would protect against prostate cancer — and other diseases. A large study of almost 35,000 men turned up no reduction in risk but a hint of an increase in risk with vitamin E. That study began a decade ago and the results were published in 2008.
This new study continued to follow the 35,000 men though July of this year. The men had taken daily supplements for three years beginning in 2001. They were randomly assigned to take either vitamin E, selenium, both, or a placebo. Compared to those who had taken a placebo, the men who had taken vitamin E had a 17 percent increased risk of developing prostate cancer. No link was found with selenium.
The findings suggest the health effects can continue even after men stop taking the supplement.
The study was published in JAMA; here’s the abstract.
Another large new study focused on older women. Here, researchers found that several commonly-used supplements linked to an earlier death.