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Frequently Asked Questions

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Following are questions that have been asked by visitors to the UW Health website and answered by registered dietitians from the UW Carbone Cancer Center.


Q: My family has a history of estrogen receptor-positive (ER+) breast cancer. Could eating soy or taking soy supplements reduce my risk of breast cancer?


A: Previously there was concern that soy foods may increase risk of estrogen receptor-positive (ER+) breast cancer due to their weak estrogen-like effect. Study regarding soy foods is ongoing and current evidence shows that soy food, in addition to a healthy, plant-based diet, may help protect against breast cancer.


Moderate consumption (1-2 servings per day) of whole soy foods is considered safe. One serving of soy provides about 7 grams of protein and 25 milligrams of isoflavones. Soy foods are a good source of low-fat protein and are rich in dietary fiber, potassium, magnesium, polyunsaturated fat, selenium, and may be fortified with calcium.


Whole soy foods include tofu, soy milk, soy nuts, or edamame. A serving size may include: ½ cup edamame, 1/3 cup tofu, 1 cup of soy milk, ½ cup cooked soy beans, 1/3 cup or 1 ounces soy nuts. Avoid high dose isoflavone supplements and high dose isolated soy protein as the health effects are unknown at this time.


Sources: American Institute for Cancer Research; Academy of Nutrition and Dietetics Oncology Nutrition Dietetic Practice Group