Registered dietitian Carole Havrila, who works with cancer patients, and Brandy Patterson, MD, discuss the benefits of soy and debunk myths surrounding the controversial food.
Soy and Estrogen
Q: Many people are concerned about estrogen in soy, but is there really enough estrogen in soy for it to make a difference?
Havrila: Plant-based estrogen (or what is often referred to as estrogen), called isoflavone, isn’t actually estrogen. Isoflavones have a chemical structure that looks somewhat like estrogen, which explains their name “phytoestrogens.”
However, isoflavones are NOT the same as female estrogens and soy foods do not contain estrogen. In some studies, soy acts more like the medicine Tamoxifen, preventing estrogen from binding to cells and exerting harmful effects in women’s body.
Large research studies show no significant effect of eating whole soy foods in amounts typical to a traditional Asian diet (1-2 servings) on male hormones. Since isoflavones are not estrogen, they do not have feminizing effects in men.
Soy and Heart Disease
Q: Can soy help prevent cancer? Does it have any helpful or preventive traits?
Havrila: Studies seem to show that whole soy foods, and the intake of these foods may be associated with lower incidences of breast cancer. Whole soy foods are products that contain unprocessed soy, such as edamame and soy beans. Tofu, a common soy food, is not considered a whole food because it is slightly processed. Research studies show that diets that include whole soy foods tend to be associated with a decreased likelihood of breast cancer recurrence in those who have had the disease. In some men, soy food intake is associated with decreased risk of developing prostate cancer, but this is not seen in all men.
Q: Does soy help reduce your risk of heart disease?
Patterson: There is much controversy over the many potential health benefits of consuming soy. Furthermore, there have been differences in Eastern and Western health outcomes and consumption of the legume. Soybean consumption in Asia, typically around 100-200g per day, almost always involves a form of the legume that is whole-food-related. In sharp contrast, consumption of soy in the United States seldom involves a whole food form. This includes soy protein powders, soy cheese, and soy “meat” products, which often contain less nutritional benefit than less or unprocessed whole soy foods.
Reports on cardiovascular health have been mixed, with some studies showing larger impacts on lowering LDL (or “bad”) cholesterol and others showing minimal effects. In 2006, a study concluded that soy protein’s effects on LDL cholesterol and other cardiovascular disease risk factors was not significant, compared with other proteins. The study suggested that “a very large amount of soy protein, more than half the daily protein intake, may lower LDL cholesterol by a few percentage points when it replaces dairy protein or a mixture of animal proteins.”
With that in mind however, they also reported that “soy products such as tofu, soy butter, soy nuts, or some soy burgers should be beneficial to cardiovascular and overall health because of their high content of polyunsaturated fats, fiber, vitamins, and minerals and low content of saturated fat. Using these and other soy foods to replace foods high in animal protein that contain saturated fat and cholesterol may confer benefits to cardiovascular health.”
Introducing Soy to Your Diet
Q: Sometimes people want to cut down on meat or fatty foods by introducing soy into their diets. What are some good ways to do this? Any recipes?
Patterson: According to Whole Foods Market, “genetically modified (GM) soybeans have reached 90 percent market penetration in the United States.” Therefore, they recommend you select organically grown soy products to avoid GMO. An easy way to introduce soy into the diet may be as simple as using soymilk, soy protein powder and fruit to make a wonderful smoothie. Simply tossing edamame beans into your salad is also an easy way to incorporate soy. Soy products such as soy hotdogs, which can be dressed up with chopped onions, mustard and ketchup, make it difficult to taste the difference between meat and soy. Tofu may replace chicken or meat in pad thai, tacos or stir-fry. Soy hotdogs, soy cheese, soymilk and edamame are some of my favorite products
Havrila provides her soy cheat sheet:
Shelled versus unshelled edamame: Most people don’t eat the pod, and it is hard to shell the edamame unless the pod is cooked, so I recommend cooking and then popping out the edamame to eat. Many places sell shelled edamame already cooked, which is an easy and convenient protein source to add to soups or salads or for a snack.
Additives: If you don’t want any, buy plain tofu and season it yourself or eat it plain. They do sell Asian, smoked and other flavors that make eating on a salad, or part of a stir fry, very easy.
Calcium: When tofu is bought fresh, it is usually in a water bath that has added calcium. If you are looking to increase the calcium intake of your diet, look at food labels for those with the most calcium per serving (look for a higher percentage on the Nutrition Facts section).
Fat: I look for lower fat versions of tofu, as these products usually contain fewer calories per serving. Silken, or soft, tofu is usually lower in calories than firm or extra firm tofu.
Patterson adds: There is recent evidence that consuming soy protein may lower systolic blood pressure and that it contains active antioxidants such as flavonoids and isoflavonoids. Another group of antioxidant phytonutrients called phenolic acids has also been recently investigated in soybeans. When we enjoy this antioxidant-rich legume, we also benefit from its phenolic acids.