Content revised and edited from “Does Breast Cancer Feed Off of Soy?” originally written by Courtney Sikora, Nutrition Therapist, and Mariah Jackson, Assistant Professor of Medical Nutrition.

Finding ways to reduce our overall cancer risk is important to our health. People often ask about the link between dairy and cancer or whether or not cancer feeds off of sugar. The question of soy and its relationship with breast cancer is common among survivors. It is a topic that has been vigorously studied for over 25 years. Does eating soy cause breast cancer to return? What about soy sauce or soy milk? Are there benefits to eating soy as a part of a well-balanced diet?

Soy and breast cancer risk

Soy contains isoflavones, which are natural plant compounds similar to human estrogen, but are not the same, which has led to some misconceptions about their impact on breast cancer. Soy isoflavones have been studied in relation to breast cancer treatment, outcomes, and chances of cancer recurrence. Current research shows that soy or soy-containing foods do not cause cancer to spread, come back or grow. Even more, research supports the opposite: Adding soy as part of a healthy, cancer-prevention diet has benefits to your health.

Studies show that soy is protective against breast cancer and the chance of it returning

According to research, soy is safe for breast cancer survivors and may actually prevent cancer. Several studies show that a higher isoflavone intake during childhood and adolescence may lower the risk of breast cancer formation in later years. In women that fought breast cancer, the study also showed that the consumption of foods rich in soy isoflavones lowered the death risk by 29% and the risk of cancer recurrence by 32%.

Consistently, clinical trials show that soy intake does not negatively affect breast cancer risk, including density of breast tissue and cell growth. Epidemiologic studies involving over 11,000 women from the United States and China show that soy intake after diagnosis improves survival rates and significantly reduces recurrence.

Current recommendations include adding one serving of soy per day as part of a healthful diet for breast cancer survivors. This includes fruits, vegetables, whole grains and lean protein for a well-balanced diet.

Adding soy can be a great way to add protein, fiber, and healthy fats to your meals and snacks. Think about healthy options like edamame, soy nuts, soy milk, tempeh or tofu.

No matter where a person is in their cancer diagnosis, eating soy as part of a well-balanced diet is not harmful. Fruits, vegetables, and whole grains with meals, along with soy can aid in getting important vitamins and minerals, boosting overall health.

Read more about what evidence-based science says about alkaline diets, acidic foods and cancer prevention.