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Multivitamins May Help Prevent Cancer

Older Men Who Took Vitamins Had Modest Reduction in Cancer, but Experts Can't Say if Findings Apply to Others
WebMD Health News
Reviewed by Louise Chang, MD

Oct. 17, 2012 (Anaheim, Calif.) -- Taking a daily multivitamin for years may lower the risk of cancer, according to new research.

The study followed nearly 15,000 middle-aged and older men for about 11 years. It is not yet clear if the findings would apply to women or younger men.

"The main findings were a reduction in total cancers of 8%,'' says researcher J. Michael Gaziano, MD, MPH, a researcher at Brigham and Women's Hospital and Harvard Medical School.

''Our main message is that the main reason to take a multivitamin is to prevent nutritional deficiency,'' Gaziano said at a news briefing today at an American Association for Cancer Research meeting held here.

"It appears there is a modest benefit for cancer reduction in men over 50," he said.

The findings are also published today in the Journal of the American Medical Association.

Vitamins and Cancer Risk: Details

The men were enrolled in the Physicians' Health Study (PHS) II. It studied the long-term effects of taking a multivitamin on the prevention of chronic disease, including cancer.

In the study, about half of the 15,000 men took a daily multivitamin, Centrum Silver. The other half took placebo. When they started the study, they were 50 or older.

At the start, 1,312 men had a history of cancer, but none had active cancer.

The researchers tracked the men to see who developed cancers, except non-melanoma skin cancers.

Cancer by the Numbers

In the vitamin group, there were 1,290 cancers. In the placebo group, there were 1,379.

About half of the cancers in each group were of the prostate.

Those diagnoses, the researchers say, were probably influenced by the increase in screening for prostate cancer during the study.

Most of the prostate cancers were earlier stage, with high survival rates.

When the researchers looked at cancers overall, they found the 8% reduction. No effect of a vitamin was found on prostate cancer by itself.

When the researchers separated out the prostate cancers, they found a 12% reduction in the incidence of all other cancers.

The researchers found no differences in the risk of death from cancer between the groups.

Health behaviors that could affect cancer risk, such as smoking and exercise, were evenly divided between groups, Gaziano says.

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