Daily multivitamin use linked to lowered men’s cancer risk
Taking a multivitamin may help prevent cancer in healthy middle-aged men.
After a series of conflicting reports about whether vitamin pills can stave off chronic disease, a new study of multivitamin use in men has a surprising message: This one worked. Researchers announced that a large clinical trial of nearly 15,000 older male doctors followed for more than a decade found that those taking a daily multivitamin experienced 8 percent fewer cancers than the subjects taking dummy pills.
The doctors, who were followed for between 10 and 13 years, were excellent patients. They were pretty healthy, with a mean body mass index of 26 — just barely overweight — and only 3.6 percent of them smoked. They were also good sports: By the end of the trial, more than two-thirds of the docs were still taking their pills as directed, the study found.
“It does appear that there is a modest reduction in cancer among middle-aged and older men,” said Dr. J. Michael Gaziano, chief of the division of aging at Brigham and Women’s Hospital and a researcher at the VA Boston Healthcare System.
While many studies have focused on the effects of high doses of particularvitamins or minerals, like calcium and vitamin D, this clinical trial examined whether a common daily multivitamin had an effect on overall cancer risk. A randomized, double-blinded clinical trial, the kind considered the most rigorous type of study; it was one of the largest and longest efforts to address questions about vitamin use.
The reduction in total cancers was small but statistically significant, said the study’s lead author, Dr. J. Michael Gaziano, a cardiologist at Brigham and Women’s Hospital and the VA Boston Healthcare System. While the main reason to take a multivitamin is to prevent nutritional deficiencies, Dr. Gaziano said, “It certainly appears there is a modest reduction in the risk of cancer from a typical multivitamin.”
The study also found that multivitamin use cut site-specific cancers, except for prostate cancer, by 12 percent, and suggested a 12 percent reduction in deaths caused by cancer, though that figure wasn’t statistically significant.
“Even total mortality went in the right direction,” said Gaziano, whose new data comes from the Physicians Health Study II published Wednesday in the Journal of the American Medical Association.
The study was supported by the National Institutes of Health and a grant, initiated by the investigators, from the chemical company BASF. Pfizer provided the multivitamins. The sponsors did not influence the study design, data analysis or manuscript preparation, the authors said.
The finding is important in a country where more than half of U.S. adults use dietary supplements, according to the Centers for Disease Control and Prevention — and where the most common supplement is a daily multivitamin.
Though several researchers said they were somewhat surprised by the findings, others called the results encouraging.
“It is a small overall effect, but from a public health standpoint, it could be of great importance,” said Dr. E. Robert Greenberg, an affiliate at Fred Hutchinson Cancer Research Center in Seattle. “Other than quitting smoking, there’s not much else out there that has shown it will reduce your cancer risk by nearly 10 percent.”
Multivitamin use had no effect on the incidence of prostate cancer, which was the most common cancer diagnosed in the study participants. When researchers looked at the effect of vitamin use on all other cancers, they found a 12 percent reduction in occurrence. Overall cancer deaths were reduced among vitamin users, but the difference was not statistically significant.
A major limitation of the study is that it included only male doctors, who were particularly healthy, with extremely low smoking rates, said Marji McCullough, a nutritional epidemiologist with the American Cancer Society. “We still need to find out whether these findings can be applied to others in the population,” she said.
The research effort might have benefited from the fact that the doctors who participated were diligent about taking their pills, and the researchers suggested that the effect of multivitamin use might have been muted because the participants were health-conscious to begin with.
Dr. David Chapin, 73, a gynecologist at Beth Israel Deaconess Medical Center in Boston who participated in the trial, said that although he had “never believed” in vitamins, he might start taking a daily multivitamin now, despite the modest benefit.
“A lot of studies make big news, but when you look at the nitty-gritty, they don’t show all that much,” Dr. Chapin said, adding that he recently discovered he had been taking a placebo pill. “This was a very reliable study, it was very well designed and administered, and it went on and on and on.”
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