NYS Certified Nutritionist

Mayo Clinic Report on Soy and Breast Cancer

Many newly diagnosed patients with breast cancer are told to avoid eating soy products, causing concern and confusion among those women who enjoy one or two servings of soy products daily.  The Mayo Clinic recently reported reassuring information from the Shanghai Women’s Health Study, analyzing questionnaires from 70,578 women between the ages of 40 and 70.

“This study’s results are in line with previous research demonstrating that soy foods lower a woman’s risk of developing breast cancer. The greatest benefit appears to be in premenopausal women,” reported the Mayo Clinic. In addition, the study found that soy foods significantly reduced the risk for some types of breast cancer, but not others.

The consumption of soy products appears to lower the risk of estrogen receptor positive and progesterone receptor positive breast cancer in all women, with the greatest protection offered to premenopausal women.  The Mayo Clinic report goes on to say, “There doesn’t appear to be an association with human epidermal growth factor receptor 2 [HER2] status and soy intake.”

The Shanghai study concluded that 1-2 servings of whole soy foods a day do not increase, and may decrease, breast cancer risk.  [No assurances can be made for soy protein isolate, soy powders, soy protein bars, etc.]  Eating like Asian women have for thousands of years, makes sense and has protected them from the incidence of hormone driven breast cancer, experienced in the US.  One serving of soy is 1 cup of soy milk, 1/2 cup of edamame, 1/3 cup soy nuts, 1/2 cup tofu, or 6 oz soy yogurt.

Soy foods are nutritious and are good sources of protein, calcium, manganese, and selenium.  Containing little total fat and virtually no saturated fat, some contain good amounts of fiber.