The use of a daily multivitamin slightly lowers the risk of cancer in older men, according to a large, randomized study published Wednesday in the Journal of the American Medical Assn. The men in the trial took the common multivitamin Centrum Silver, which is produced by Pfizer.
The results are at odds with a host of other studies in recent years that have shown no positive effect of vitamins on cancer rates -- and some that have found such supplements can be harmful. But many of those studies were focused on individual vitamins, such as vitamin D and vitamin B6, that animal research suggested had cancer-preventing properties. In most studies, those single vitamins are given to people in large doses, far above the level found in a multivitamin such as the one used in the study.
In the new study, researchers analyzed data collected as part of the Physicians' Health Study II, which followed 14,641 male doctors age 50 and older for an average of 11.2 years. During that time, the doctors were randomized into groups that received either the multivitamin or a placebo.
Compared with the doctors taking the placebo, the doctors who took the multivitamin were 8% less likely to develop any type of cancer over the course of the study -- a modest but significant difference. The overall cancer rates were 17.6% in the multivitamin group and 18.8% in the placebo group.