Ask the Nutritionist
Q: Should breast cancer survivors avoid soy milk? I'm an 11-year survivor and I love soy milk in my coffee.
Janet, Somerville, Massachusetts, October 2015
A: It is not necessary for breast cancer survivors to avoid all types of soy foods. Current research indicates that survivors with an estrogen receptor-positive breast cancer can enjoy whole soy foods like soy milk, tofu, edamame, tempeh and soy nuts. According to the American Institute for Cancer Research, moderate consumption of whole soy foods, or 1-2 servings per day, does not increase cancer risk, and may actually lower the risk of cancers of the breast, prostate, and other cancers. One serving is one cup of soy milk, a half cup of cooked edamame or soy beans, or one ounce of soy nuts.
That being said, research is lacking in regard to high doses of soy in supplements like soy protein isolates. Since less is known about their effects on health, isolated soy compounds or soy supplements should be avoided if that is a concern. Avoid foods made from soy protein powder, soy protein isolate, or isolated soy protein (read the ingredient list to look for these). These forms of soy are often found in nutrition bars, soy protein powder, many high protein breads and cereals and vegetarian "meat-less" options, such as certain brands of veggie burgers or soy hot dogs.
Foods with soy in the name that do not have any phytoestrogen activity and are safe to eat include: soybean oil, soy sauce, and foods made with soy lecithin.
To promote overall health, it is best to eat a variety of fruits, vegetables, whole grains, lean proteins, and healthy fats. Nutrition and Healthy Living provides recommendations for health in survivorship.