An estimated one-third of Americans take a daily multivitamin supplement, the composition of which mimics healthy fruit and vegetable compounds. J. Michael Gaziano, from Harvard Medical School (Massachusetts, USA), and colleagues analyzed data collected in the Physicians’ Health Study (PHS) II, that includes 14,641 male U.S. physicians, initially age 50 years or older. Subjects received a daily multivitamin or equivalent placebo, and were followed for an average of 11.2 years. During multivitamin treatment, there were 2,669 confirmed cases of cancer, including 1,373 cases of prostate cancer and 210 cases of colorectal cancer, with some men experiencing multiple events. A total of 2,757 (18.8%) men died during follow-up, including 859 (5.9%) due to cancer. Analysis of the data indicated that men taking a multivitamin had a modest 8% reduction in total cancer incidence. The researchers found that a multivitamin significantly reduced the risk of total cancer (excluding prostate cancer – the early stage of which was the cause of half of all incident cancers in the study). There were no statistically significant reductions in individual site-specific cancers, including colorectal, lung, and bladder cancer, or in cancer mortality. Reporting that: “Daily multivitamin use was associated with a reduction in total cancer among 1312 men with a baseline history of cancer,” the study authors conclude that: “In this large prevention trial of male physicians, daily multivitamin supplementation modestly but significantly reduced the risk of total cancer.”
