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# Taking multivitamins may raise breast cancer risk
- URL: https://www.foodconsumer.org/multivitamins_may_raise_breast_cancer_risk_0104100834/
- Published: 2010-04-01T20:32:00.000Z
- Updated: 2026-09-22T16:02:55.000Z
- Description: Following 35,000 Swedish women aged 49 to 83 for a decade, researchers found those taking multivitamins were 19 percent more likely to be diagnosed with breast cancer. The design cannot show cause, and the authors note supplement users may already have been at higher risk.
- Author: Food Consumer
- Tags: Vitamins, Nutrition, Breast Cancer, Vitamin, #vivvo-import

A new study suggests that taking multivitamins may increase risk for breast cancer. It should be noted that this is just a suggestion because the study is not a trial meaning that it has not established any causal relationship.

The study led by world-famous researcher Susanna C. Larsson Ph.D. at the Karolinska Institute in Stockholm, Sweden and colleagues found women taking multivitamins were 19 percent more likely to develop breast cancer than those who did not take daily multivitamins.

For the study, the researchers followed 35,000 Sweden women aged 49 to 83 for 10 years. Of the participants, 9,017 women reported taking multivitamins. During the follow-up, 974 women were diagnosed with breast cancer. Of them, 293 were taking multivitamins.

The researchers found the increased risk of breast cancer had nothing to do with vitamin E, C and B-6 while calcium was found to provide some protection against breast cancer.

The study was published online in the American Journal of Clinical Nutrition.

Although the study per se could not prove taking multivitamins increased risk of breast cancer, the researchers suggested that the possibility is real. They cited studies linking folic acid to elevated risk of breast cancer and high intake of iron and zinc to increased risk of cancer.

Another explanation is that those women who took multivitamins might have had some known underlying condition that put them at higher risk of cancer, which prompted them to take multivitamins in hopes that these nutrients can help reduce the risk.

Or could something else raise the risk of breast cancer?

Breast cancer is diagnosed in more than 170,000 women each year in the United States and the disease kills about 50,000 annually in the country. One in every eight women in the U.S. will be diagnosed with the disease.