Can multivitamins lower cancer risk in men?
Multivitamins are the most common dietary supplement in the US; at least one out of three adults regularly take them. Most take them to insure that they do not suffer from a nutritional deficiency. Alternatively, a diet high in a variety of fresh fruits and vegetables can provide daily requirements for essential vitamins. This type of diet has also been reported to slightly reduce the risk of cancer. Researchers affiliated with Brigham and Women’s Hospital (Boston, MA), and the VA Boston Healthcare System Department of Medicine conducted a study to determine whether a daily multivitamin would reduce the risk of cancer in men. The researchers published their findings online in the Journal of the American Medical Association (JAMA). Although the study group comprised men, it is likely that the results would also apply to women.
The researchers noted that observational studies of long-term multivitamin use and cancer risk have been inconsistent. In addition, they noted that, to date, large-scale randomized trials testing single or small numbers of higher-dose individual vitamins and minerals for cancer have generally found a lack of effect. The researchers conducted a large-scale, randomized, double-blind, placebo-controlled trial termed the Physicians' Health Study II. The study group comprised 14,641 male US physicians initially aged 50 years or older (average age: 64.3 years), including 1,312 men with a history of cancer at the study onset. The men were enrolled in a common multivitamin study that began in 1997 with treatment and follow-up through June 1, 2011. The main outcome measures were the total number of cancers (excluding nonmelanoma skin cancer); secondary outcome measures were the number of prostate, colorectal, and other site-specific cancers. The subjects took either the multivitamin Centrum Silver (Pfizer, New York, NY) or a placebo daily.
The researchers found that during an average follow-up of 11.2 years, there were 2,669 men with confirmed cancer, including 1,373 cases of prostate cancer and 210 cases of colorectal cancer. Compared with the placebo, men taking a daily multivitamin had a statistically significant reduction in the incidence of total cancer (multivitamin group: 17.0 events per 1000 person-years; placebo group: 18.3 events per 1000 person-years). There was no significant effect of a daily multivitamin on prostate cancer (multivitamin and placebo groups, 9.1 vs. 9.2 events per 1000 person-years), colorectal cancer (multivitamin and placebo groups, 1.2 vs. 1.4 events per 1000 person-years), or other site-specific cancers. There was no significant difference in the risk of cancer mortality (multivitamin group: 4.9 events; and placebo group: 5.6 events). Daily multivitamin use was associated with a reduction in total cancer among 1,312 men with a baseline history of cancer; however, this did not differ significantly from that among 13,329 men initially without cancer.
The authors concluded that in this large prevention trial of male physicians, daily multivitamin supplementation modestly but significantly reduced the risk of total cancer.
Take home message:
A daily multivitamin insures that one receives all necessary vitamins and this study notes a slight reduction in cancer risk. A diet high in fresh fruits and vegetables provides many health benefits beyond what a vitamin supplement can provide. If one takes a daily multivitamin but makes other poor lifestyle choices (i.e., cigarette smoking, lack of exercise, and excessive alcohol), any benefit from the multivitamin is markedly counteracted by those choices.
Photo Credit: Pfizer and Robin Wulffson, MD