Tofu, tempeh and miso all seem like great high protein choices for the nine days. However all these products contain soy, and today many people are leery about consuming soy. Is there reason for their concern?
Soy used to be thought of as a health food. It was an item that vegetarians would eat. It was a good substitute for individuals trying to cut back on cholesterol or for those with lactose intolerance. In fact, the Food and Drug Administration claims that “25 grams of soy protein per day, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease.”
Recently, however, soy has been relegated to the black list. If I mention that I enjoy tofu for dinner or that my son prefers soy milk, I get a gasp and a sigh.
“My doctor told me that soy can cause cancer.” Or, “But he is a boy. Why would you want him drinking something that contains estrogen?”
But it is not merely the yenta factor that has attached itself to the soy issue. Researchers have also been focused on the pros and cons of soy. In recent years nearly 2000 papers annually were devoted to this topic. So, what is the story behind soy?
A main concern that individuals have is that isoflavones found in soy bind to estrogen receptors and can exhibit weak estrogen-like effects. Claims have been made that if men consume soy it may have a “feminizing effect,” decreasing testosterone levels and increasing estrogen levels. However, a review paper published in Fertility and Sterility in 2010 looked at the data from over 150 clinical studies and concluded that consumption of soy products does not have an effect on circulating levels of testosterone or estrogen in men.
Another question related to the isoflavones is whether it may pose a danger to women at high risk for breast cancer or women who have had breast cancer. A study published in the American Journal of Clinical Nutrition in 2012 examined the research from multiple cohort studies that included 10,000 breast cancer patients from both the United States and China. The researchers found that, on the contrary, consuming greater than 10 mg of isoflavones daily was associated with a reduced risk of breast cancer recurrence. The American Cancer Society states that the current research does not find any negative effects from breast cancer survivors consuming soy.
Another worry individuals may have with soy is how it can affect the thyroid. Some soy foods contain a substance called goitrogens, which can interfere with the production of thyroxine (the thyroid hormone). When examining the literature, researchers have found that consumption of soy products does not seem to adversely affect thyroid function in healthy adults. Still, if one has hypothyroidism and is taking medication, such as levothyroxine, s/he should be careful to take the medication four hours prior to ingesting soy as soy protein may interfere with its absorption.
One of the benefits of soy is that it contains a variety of wonderful nutrients. One cup of soybeans is an excellent source of protein, fiber, iron, calcium and phytochemicals (chemical compounds that occur naturally in plants that may have biological significance, for example antioxidants, but are not established as essential nutrients). However, this does not mean that all soy products are beneficial: Many foods containing soy, such as protein bars, soy patties and vegetarian meat analogues are highly processed and often stripped of many of these nutrients. The bottom line seems to be that consuming 2-3 servings of soy a day is a safe and nutritious alternative to meat. However, it is wise to choose minimally processed forms such as soy nuts, tempeh and edamame and to steer clear of soy supplements.
Shoshana Genack is a dietician practicing in the metropolitan area. She can be reached at shoshanagenack_gmail.com
By Shoshana Genack
