A prevention trial performed on male physicians revealed that taking a daily multivitamin modestly reduced the occurrence of cancer in men, according to a study by Harvard Medical School researchers published Wednesday in the Journal of the American Medical Association.

This study is the first long-term, randomized clinical trial to suggest the benefits of taking regular doses of multivitamins, according to HMS professor Howard D. Sesso, who is the study’s co-principal investigator. Similar studies in the past have involved high doses of single vitamins or other combinations that aren’t available to consumers, added the lead author, HMS professor J. Michael Gaziano.

In the study, 14,641 male physicians over the age of 50 were given either multivitamins or placebos through the mail over the course of 11 years.

“We [tested only physicians] because they reported their health information well and it was easy for us to consent them, because they understood what we were trying to do…and the importance of sticking with it,” said Gaziano, who works in Brigham and Women’s Hospital’s Division of Aging.

According to Sesso, whenever a participant reported a change in their health—like the occurrence of cancer—their medical records were requested and examined by a committee of physicians that either confirmed or unconfirmed the initial self-report.

The group that took the multivitamins experienced 8 percent fewer cases of cancer compared to the placebo group, according to Gaziano.

“It was very well administered, and the controls were well randomized,” said David S. Chapin ’60, a participant in the study and an HMS professor. “The number of people and the length of time makes it so the results are believable.”

While the study only involved healthy males over the age of 50, Sesso believes the benefits might extend to other groups as well.

“We seem to think that the mechanism of effect of a multivitamin is blind to who’s taking it,” he said. “If it’s the combo of all the vitamins and minerals together that interact together to potentially reduce cancer risk, it might not matter whether you’re a man woman or otherwise.”

Sesso said that at least one third of all U.S. adults take multvitamins.

Because of this fact, Chapin said that any findings about multivitamins are significant.

“Vitamins are a multi-billion dollar industry in our country and people may be throwing away their money if there’s no benefit,” he said.

While he said he believes the reduction in cancer rates in the study is fairly small, Chapin said that he will continue to take vitamins.

“I’m not running out to buy them today, but the next time I’m in Costco, I’ll probably buy some vitamins,” said Chapin.