Multivitamins and Cancer Prevention: Using the Data

A Best Evidence Review

Charles P. Vega, MD; Megan Tan


December 14, 2012

In This Article


The current study is important because it is the first randomized trial of a multivitamin in the primary prevention of cancer. Moreover, its positive result has generated considerable public interest and should help to boost sales of all vitamin products.

However, the study also has substantial limitations. The overall positive effect of multivitamins on the risk for cancer is of borderline statistical significance. The study was limited to male physicians, which is a highly selected population, and the applicability of the study results to the general population is questionable.

Many patients will come to physician's office with questions about the role of multivitamins in their health. The current study does not provide the type of incontrovertible evidence that would mandate a recommendation for the wide use of multivitamins among adults, or among men specifically. That said, regular doses of multivitamin should not be harmful. If a patient elects to take a multivitamin, the physician should review the product label to ensure that its contents are in the standards for these preparations. Multivitamins containing very high doses of antioxidant vitamins, such as vitamin A, may not be safe and should be exchanged for lower-dose preparations.[19]

Finally, it is worthwhile to take a step back and consider that reversible health behaviors, such as smoking and overeating combined with a sedentary lifestyle, contribute far more to the risk for cancer than may be improved with any multivitamin. While lifestyle changes may not be as easy as regular use of a multivitamin, the benefits of smoking cessation and weight loss would have a much more profound effect on the risk for cancer. Therefore, the best application of the current study might be as a springboard to discuss other health habits and identify patient motivations and solutions in cancer prevention.