Multivitamin use and the Risk of Breast Cancer – A Response to a Scientific Publication

American Institute for Cancer Research, Washington, DC, USA

“Last week a study appeared online in the American Journal of Clinical Nutrition that raised some eyebrows (1). The Swedish observational study followed approximately 35,000 women (aged 49 to 83 when the study began in 1997). After 10 years, women who reported using multivitamins were 19 percent more likely to develop breast cancer than women who did not take multivitamins (…). The researchers said the apparent link merits further investigation.

The role of supplements in cancer risk is complex and anything but clear-cut *. This one new study is not, in itself, a reason to throw out your one-a-day vitamin. But it is a reason to redouble your efforts to eat a varied and healthful diet full of vegetables, fruits, whole grains and beans and low in red meat. That’s the overall pattern of eating that has been consistently associated with lower risk for cancer (…). Some individuals who have nutrient deficiencies could benefit from a daily multivitamin (…).”

Washington, DC, April 2010

* There is also data supporting some anti-cancer activity, with a US National Cancer Institute-sponsored study reporting that multivitamin supplements that are rich in vitamins A, B9 (folic acid), C and K, and carotenoids may reduce the risk of lung cancer in smokers (2). Moreover, a study found that multivitamin and calcium supplements have a protective effect against breast cancer: Researchers who surveyed 268 breast cancer patients and 457 healthy controls found that participants who took multivitamin supplements reduced the odds of having breast cancer by 30 percent, and those who took calcium had a 40 percent decreased risk (3).