Studies show that eating a moderate amount of soy foods does not increase risk of breast cancer — or other types of cancer. A moderate amount is considered one to two servings a day of whole-soy foods, such as tofu, soy milk and edamame. Soy contains protein, isoflavones and fiber, all thought to provide health benefits.
So where did the idea come from that soy increases breast cancer risk? Isoflavones, which are found in soy, are plant estrogens. High levels of estrogen have been linked to an increased risk of breast cancer. However, food sources of soy don't contain high enough levels of isoflavones to increase the risk of breast cancer.
April 07, 2015
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- AskMayoExpert. Soy. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2014.
- Your questions on soy and breast cancer answered. American Institute for Cancer Research. http://www.aicr.org/enews/2014/10-october/eNews-Your-Questions-on-Soy-and-Breast-Cancer-answered.html. Accessed Dec. 5, 2014.
- Chen M, et al. Association between soy isoflavone intake and breast cancer risk for pre- and post-menopausal women: A meta-analysis of epidemiological studies. PLOS One. 2014;9:e89288.
- Soy. Natural Medicines Comprehensive Database. http://www.naturaldatabase.com. Accessed Dec. 5, 2014.