Ask the Nutritionist
Q: I have breast cancer that is estrogen related. Can I still eat plant-based estrogen products like soy or prunes, or animal products like cows’ milk, etc.?
Linda, Worcester, MA, October 2015
A: There is a lot of controversy surrounding consumption of phytoestrogens and soy products for patients with estrogen sensitive cancer.
The concern with soy and cancer comes from the fact that soy contains isoflavones, which are phytoestrogens that in some ways mimic the action of estrogen. However, these phytoestrogens are many times weaker than the estrogen made in human bodies. According to the American Institute for Cancer Research and American Cancer Society, research has shown that moderate consumption of whole soy foods appears safe for both breast cancer survivors and the general public. 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.
In fruits and vegetables, the benefits greatly outweigh any potential negatives of their minimal phytoestrogen content. Any phytoestrogen effect from vegetables or fruits, such as prunes, is negligible and has not been shown to be harmful in any way. Phytonutrients found in fruits and vegetables promote immune support and detoxification in the body and are excellent sources of disease-fighting nutrients.
Research has shown that grass fed beef has a more preferable nutrient profile than conventionally raised beef, so when possible it may be beneficial to choose organic grass-fed beef. We recommend following the American Institute for Cancer Research’s guideline of consuming no more than 11-18oz of red meat per week. For overall cardiovascular health, it is best to choose leaner cuts of meat to limit saturated fat intake and overall calorie intake. However, regular consumption of processed red meats like bacon, hot dogs and sausage, is not recommended as they are associated with a higher risk of colorectal cancer, heart disease and type 2 diabetes. Similarly dairy can be part of a healthful diet as it is a great source of protein, calcium and other nutrients. As with red meat, organic dairy products from grass fed cows has a more preferable nutrient profile, so choose organic dairy products when possible. A local farm that offers a dairy and meat CSA (community supported agriculture) is a great choice.
Please read more about the potential phytoestrogen effect of flaxseeds.