Gaziano et al report the results of a large randomized controlled trial in JAMA (2012). They studied more than 14,000 men with a median follow-up of 11 years. The subjects were physicians older than 50 years of age at the time of enrollment with the aim of seeing whether cancers could be prevented. They reported that prostate cancer made up nearly half of the cancers diagnosed, and that there was no difference in the incidence of prostate cancer found between men taking placebo or those taking multivitamins. The incidence of colon cancer was also the same in both groups. However, overall, there were fewer total numbers of cancers, excluding prostate cancer, in the group that received the daily multivitamin. Side effects were few but not very major.