The Dietary Supplement Genistein Can Undermine Breast Cancer Treatment, University of Illinois Virginia Polytechnic, Virginia State University and the National Center for Toxicological Research Study  
10/2/2008 7:35:50 AM

UIUC -- Women taking aromatase inhibitors to treat breast cancer or prevent its recurrence should think twice before also taking a soy-based dietary supplement, researchers report. Genistein, a soy isoflavone that mimics the effects of estrogen in the body, can negate the effectiveness of aromatase inhibitors, which are designed to reduce the levels of estrogens that can promote tumor growth in some types of breast cancer.