Can noshing on edamame help you reduce your cancer risk image: elena elisseeva

Soy beans are about the size of a pea, but they’ve racked up some serious health cred over the years. Whether that’s warranted or not often depends on who you ask. Soy products, like tofu and edamame, are often hailed as an excellent protein substitute for vegetarians and Meatless Monday enthusiasts and a potential way to reduce the risk of breast cancer. But skeptics have questioned whether soy is a high-calorie protein that increases estrogen levels. With all the chatter, it’s time to separate important facts about soy from total fiction.

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Is soy a good source of protein?
Soybeans are an excellent source of protein. They are part of the legume family (a family of plants whose seeds are often used to harvest beans, lentils, peas, etc.) and contain protein, fiber, zinc and other amino acids. Soy can be made into tofu, tempeh, soy cheese and many other protein substitutes.

Does soy reduce the risk of breast cancer?
There has been conflicting evidence on the effects of a diet high in soy in individuals with breast cancer. The most recent study on this topic reached two interesting conclusions. First, a diet high in soy during adulthood and adolescence was associated with reduced premenopausal breast cancer risk. On the other hand, a diet high in soy during adulthood alone was associated with postmenopausal breast cancer only when adolescent intake was low. Overall, the findings suggested that the most important factors associated with the soy-breast cancer relationship are hormone receptor type (ex. HER2+ or estrogen/progesterone receptor +), menopausal status and age of exposure to a diet high in soy.

Can soy cause higher estrogen levels in my body?
Yes, soybeans are known to contain isoflavones, which are biologically active compounds linked to the estrogen receptor found in mammals. I think this is especially important in some types of cancer, such as endometrial cancer which can be affected by high levels of estrogen in the body. On the other hand, medical research is looking into the positive effects of a diet high in soy in some postmenopausal types of cancer (since women’s estrogen levels decline after menopause).

How bad is the soy allergy?
The cell mediate allergic response associated with soy products is relatively low in prevalence and non-life threatening.

Are tofu or soy products high in calories?
The answer depends on a weight based diet. Since soy food is relatively higher in protein and low in carbohydrates I’d say that amount of calories is reasonable. For example, a box of tofu is about 4.5 servings of 80 calories each. The servings are small, so if eaten in one meal a full box of tofu is about 400 calories. Compare this to the amount of meat you eat in a day- while you may be compromising flavor a serving of tofu may contain fewer calories than a normal serving of non-lean meat.