One common question breast cancer patients ask is “what’s the story with soy?”. With all the information out there it can be tricky to get a clear answer. As with any part of treatment, it is important to have a conversation with your oncologist, primary care doctor, or dietitian to make sure you are receiving the best care for you. To help spark a conversation here is a bit of context to keep up an active dialogue regarding breast cancer and nutrition.
Soy is an excellent source of protein and fiber that makes up a variety of products including soy protein, soy milk, soy nuts, edamame, tempeh, and tofu. It has been used as a meatless alternative, and in Asian cultures, it is a staple in traditional Chinese diets. However, concern has risen around its consumption and an increased risk of breast cancer. This relationship has been rigorously studied and many sources conclude that eating moderate amounts of soy and soy products are considered safe. Meaning that moderate intake; 1-2 servings of whole soy foods; does not increase an individual’s risk of breast cancer. Some research has even determined that soy foods can help to reduce an individual’s risk of cancer if consumed early in childhood and adolescence.
The concern around soy is based on isoflavones; a class of phytoestrogens that have a component which mimics estrogen. Higher estrogen levels are a known risk factor for breast cancer, and thus the link between soy and an increased risk of breast cancer has been formed. There is still debate regarding isoflavones when it becomes concentrated in products such as soy supplements, and its varying risk in the development of breast cancer. Additional research needs to be conducted on this association, and until then caution should be used when consuming soy dietary supplements, especially for an extended period of time – six months plus. However eating a moderate amount of whole soy foods does not provide high enough levels of isoflavones to increase the risk of breast cancer in people.
So what does this mean for you? Be sure to eat a well-balanced diet full of fresh fruits, veggies – and yes some whole soy foods if you want – and to keep talking with your doctor to make sure you are getting all the nutrients you need to help you feel better, stay stronger, and recover faster.