Daily Multivitamin May Slightly Lower Men's Cancer Risk, Study Suggests

Taking a daily multivitamin could slightly decrease men's risk of cancer, according to a large new study being presented at the annual meeting of the American Association for Cancer Research and published in the Journal of the American Medical Association.

The study, conducted by researchers at Brigham and Women’s Hospital, is based on 14,641 male doctors ages 50 and older who participated in the Physicians' Health Study II. Some of the men were randomly assigned to take a daily multivitamin between 1997 and 2011, while others were assigned not to.

By the end of the study period, 2,669 new cases of cancer had developed, of which 1,373 cases were of prostate cancer and 210 cases were of colorectal cancer.

Overall, researchers found that the men who were assigned to take a daily multivitamin had an 8 percent lower cancer occurrence compared with those who didn't take the multivitamin.

Specifically, researchers didn't find that multivitamin use had any effect on the men's prostate cancer risk (even though prostate cancer was the most common cancer to affect them on a whole). However, multivitamin use was associated with a 12 percent lower risk of developing other cancers in the study.

Researchers also found that the risk of dying from cancer was 12 percent lower among men who took the daily multivitamins, but they said that this decreased risk was not statistically significant.

"This study suggests, at least for men, that there might be benefits to taking multivitamins in terms of cancer as well," study researcher Dr. John Michael Gaziano, M.D., the chief of the Division of Aging at Brigham and Women’s Hospital, said in a statement. However, they did note that the observed benefits were modest, and more research is needed to see how multivitamin use impacts men over a longer period of time, as well as whether multivitamin use has any effect in women's cancer risk.

Balz Frei, a professor and director of the Linus Pauling Institute at Oregon State University who was not involved in the research, said in a statement commenting on the study that percent decrease in cancer risk is "not small."

"Given that more than 1.6 million new cancer cases are diagnosed in the U.S. each year, this translates into about 130,000 cancers prevented every year, and with it all the health care costs and human suffering," Frei said in the statement.

Multivitamins are extremely pervasive in American culture, with one in three U.S. adults taking one every day, Next Avenue reported.

Past research on multivitamins has been mixed. For example, an Archives of Internal Medicine study last year of more than 38,000 women showed that supplement use was linked with a 2.4 percent higher risk of death during a 19-year-period, MyHealthNewsDaily reported.

Specifically for multivitamins, 40.8 percent of women who took a multivitamin every day died by the end of the study period, compared with 39.8 percent of women who did not take a daily multivitamin, according to MyHealthNewsDaily.

"Our study, as well as other similar studies, have provided very little evidence that commonly used dietary supplements would help to prevent chronic diseases," study researcher Jaakko Mursu, an epidemiologist at the University of Minnesota School of Public Health, told MyHealthNewsDaily. "We would advise people to reconsider whether they need to use supplements, and put more emphasis on a healthy diet instead."

And a 2010 study in the American Journal of Clinical Nutrition actually found an increased risk of cancer among women who took a daily multivitamin, CNN reported. That study included 35,000 women in Sweden (between ages 49 and 83), and showed that breast cancer risk was 19 percent higher among women who took a daily multivitamin compared with women who didn't by the end of the 10-year study.

U.S. News reported that the U.S. Preventive Services Task Force doesn't have a recommendation one way or another on multivitamin use -- it neither recommends them, nor recommends against them. However, there's still a lot to know, and experts generally recommend talking to your doctor to see if you need to take a multivitamin or another daily supplement due to deficiencies.

Confused about whether you should take a multivitamin? Click over to our Ask Healthy Living on the topic.