Taking a daily multivitamin pill may reduce the risk of cancer in men, a new study revealed.
The study found that men ages 50 and over who regularly used daily multivitamins were 8 percent less likely to develop cancer over 11-year period compared to men who took a placebo.
Scientists said that the lowered cancer risk was a modest but valuable reduction.
However, researchers were not able to identify a single vitamin or combination that works, suggesting that the benefit may come from a broad combination of low dose vitamins.
Additionally when the researchers analyzed men's risk of specific cancer, like prostate, lung and colon cancer, the multivitamin did not have an effect, and men who took a multivitamin were just as likely to die from cancer as men who took a placebo.
US researchers said that because the study involved only men, the same effect cannot be assumed for women, although experts believe that the effect will most likely be similar.
The study, published Oct. 17 in the Journal of the American Medical Association, involved 14,641 U.S. doctors who were initially age 50 or older, including 1,312 men with a history of cancer at randomization, who were joined in a multivitamin study that began in 1997 with treatment and follow-up through 2011.
Participants received a daily multivitamin or placebo pill and were followed for more than 11 years. The participants were given a daily pill with a brand called Centrum Silver for men over the age of 50 containing a typical range of vitamins and minerals, including vitamins A, C, D, E, B6 and B12, calcium, selenium and zinc.
Researchers said there were 669 confirmed cases of cancer, including 1,373 cases of prostate cancer and 210 cases of colorectal cancer, with some men experiencing multiple events during the study. Results showed that a total of 2,757 or 18.8 percent of men died during follow-up, including 859 or 5.9 percent of total participants due to cancer.
Researchers found that men taking multivitamins on a regular basis had a modest 8 percent drop in total cancer incidence, including colorectal, lung and bladder, but there was not a significant effect on deaths from cancer.
Researchers from the Brigham and Women's Hospital and Harvard Medical School, Boston, said that latest finding is significant as the first randomized trial of its kind.
Lead author Michael Gaziano, chief of the hospital's division of aging, said that the latest study was the first clinical trial to test the effects of multivitamins on a major disease like cancer. Gaziano said that even though more than one-third of Americans take multivitamins, their long-term effects were unknown until now.
While there were many studies that proved that eating a diet high in fruits and vegetables lowers cancer risk, research on whether vitamin supplements can do the same have produced mixed results.
Some studies on multivitamins have even suggested that vitamins may bring health risks. For example, a 2011 study of more than 35,000 men living in the U.S. found that daily supplements of vitamin E actually increased the risk of prostate cancer by 17 percent, and a 2010 study of Swedish women found that daily multivitamin intake actually increased the risk of breast cancer by 19 percent.
Researchers said that the results need to be confirmed by more studies before health care professionals can start recommending multivitamins to the public.