A quick google on the association between diet, exercise and the risk of breast cancer yields enormous results. Abundant information mixed with advertisements from every “work-out guru” and “diet-of-the-month” creates an environment which makes it impossible to carve out helpful information.
Let’s say that you are an avid scholar and researcher, and you decide to use Pubmed (The National Library of Medicine’s center for Biotechnology information) to garner your information. Even then, a simple search of the relation between diet and breast cancer returns over 4500 publications. A search for the relation between exercise and breast cancer risk yields another 4100 publications. How is anyone supposed to muster through this amount of material

The Plan
So, for the next few months, we at the Female Health Collective are going to take you through a few topics related to diet and exercise and how they affect one’s personal risk of developing breast cancer. It will range from the basic to the esoteric, from sugar substitutes (Oh my, does that have an effect? Should I switch to sugar-in-the-raw?) to weight lifting, to tofu (listen up, plant-based eaters). We’ll begin that journey today talking about soy products and their effect on your risk of breast cancer.

How It Started – Soy Products
Increased estrogen levels in the body is a known risk factor for breast cancer. In fact, many (but not all) breast cancers grow in direct response to estrogen. Isoflavones, which are molecules in soy, are plant estrogens. So, the original thought was that consuming excess soy would mean that a person was consuming excess estrogen. That excess estrogen was thought to increase the risk of breast cancer. However, isoflavones are not exact replicas of human estrogen. And, in contrast to the original thoughts, some studies actually showed that populations where soy consumption was high had lower rates of breast cancer, potentially suggesting a protective effect, rather than harmful one.
The Real Deal – Soy Products
Multiple long-term studies done to identify whether soy products in fact lead to higher rates of breast cancer fail to show a consistent threat. There are many other lifestyle-based activities which have a greater effect on your breast cancer risk (to be covered in future posts! Stay tuned!).
So What Should I Do? – Soy Products
In general, natural soy products are preferred over high processed food or those rich with isoflavone extracts. Consuming natural soy will likely not increase your risk of breast cancer, but supplements may contain several hundred times higher levels of isoflavones than natural products.
And remember to reach out to your doctor if you have any questions regarding your personal soy intake and risk of breast cancer.

Emily L. Siegel is a board certified general surgeon and fellowship-trained breast surgeon in Los Angeles, CA. After attending Williams College for her undergraduate studies, she went on to receive her MD from the USC Keck School of Medicine and subsequently trained in General Surgery at Cedars-Sinai Medical Center. After pursuing research interests in breast cancer, she finished her specialty training in Breast Oncology Surgery at H. Lee Moffitt Cancer Center in Tampa, Florida, a quaternary referral research hospital, and one of the nation’s top cancer centers. Her research interests include the surgical management of breast cancer and she is widely published in journals and medical textbooks.
Having grown up in Los Angeles, she is dedicated to providing care in the city and community in which she was raised. With interests in benign, malignant, and high risk breast disease, her practice encompasses all aspects of breast health.