Multivitamins and Breast Cancer Risk

There's been a recent flurry of reports about multivitamins and breast cancer. If you've been following the news, chances are that you're confused and not sure what to believe. Before you give up your daily multivitamin, here's a look at these studies.

In April 2010, researchers published two studies, one associating multivitamin use to an increased risk of breast cancer; the other found no link to cancer risk. The first study reports that premenopausal women who take multivitamins have significantly higher breast density, which is strongly and positively related to breast cancer risk. The researchers also found that supplementation with folic acid may increase this risk.

The second study evaluated multivitamin and calcium intake and found no correlation to increased cancer risk. The researchers did find that the subjects' DNA was better able to repair itself when damaged. Breast cancer has been associated with a decrease in DNA repair functioning, so these are positive results. They also concluded that taking supplements of individual vitamins (rather than a multivitamin) is not associated with significant cancer risk reduction.

Both studies have limitations, which makes it difficult to project results to the general population or to state a definitive relationship between multivitamins and cancer risk. These two latest studies follow many others in which researchers did not find an increased risk of cancer with multivitamin use. There have been studies, however, that vitamin D supplementation may help reduce breast cancer risk in women who have a low vitamin D intake.

Steps to Take

With all this confusing information, what should you do?

Take the results of these studies with a grain of salt. Most studies have limitations that make it difficult to declare cause and affect relationships. There are often other factors that may play a role in the study's results, but that researchers did not control for in the study. Furthermore, many studies are based on high doses of vitamins, or on individual, isolated vitamins, which do not reflect an average person's behavior.

Eat a healthy diet. Nutrients that come directly from whole foods are more beneficial than those that come from supplements. Make sure your diet includes lots of fresh fruits and vegetables in a variety of colors. Each color is associated with certain health benefits; so if you eat a well-rounded diet, you'll more likely consume the right nutrients.

Stick with multivitamins that provide the Recommended Daily Allowance (RDA) of nutrients. Avoid taking excessive vitamins unless you're under the supervision of a qualified health professional; more is not necessarily better.


Ash, Michael. "Multivitamins & Breast Cancer - Is It Too Little Rather Than Too Much?" Nutri-Link Clinical Education. Web. 19 April 2010.

"Multivitamins and prostate cancer risk." Harvard Men's Health Watch. October 2007. Web.

Mulcahy, Nick. "Multivitamin Use and Breast Cancer: Protective or Harmful?" Medscape Medical News. Web. 27 April 2010.

Brooks, Megan. "Supplemental Vitamin D May Help Reduce Breast Cancer Risk." Medscape Medical News. Web. 29 April 2010.

Ishitani, Ken, Lin, Jennifer, Mason, JoAnn E., Buring, Julie E., and Zhang, Shumin M. "A Prospective Study of Multivitamin Supplement Use and Risk of Breast Cancer." American Journal of Epidemiology 167(10) (2008): 1197-1206. Web. 9 September 2008.

Meulepas JM, Newcomb PA, Burnett-Hartman AN, Hampton JM, and Trentham-Dietz A. "Multivitamin supplement use and risk of invasive breast cancer." Public Health Nutrition 2009 Dec 3:1-6. [Epub ahead of print] Web.