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Digging Through The Soy Controversy

Soy is a fantastic source of protein that contains all of the essential amino acids. It’s also rich in various vitamins and minerals, soluble and insoluble fiber, omega-3, and omega-6 fatty acids. Many studies claim that soy has a beneficial effect in reducing the risk of heart disease, managing hot flashes, preventing osteoporosis, and protecting against some forms of cancer. Meanwhile, many people are still concerned about its potential link to breast cancer, thyroid problems, and dementia. Let’s dig into some of the common controversial questions about soy and distinguish fact from fiction.

Is soy safe for men to eat?

Because of the presence of the isoflavones (plant-derived estrogens or phytoestrogens found in many foods) in soy products, men are commonly concerned about the effects of soy on their hormonal levels and prostate health. These concerns may stem from some animal studies, where high consumption of phytoestrogens was shown to undermine male rats’ fertility. It's important to note that these studies are not correlated with humans because rodents metabolization of soy phytoestrogens is different than that of humans.

A recent meta-analysis indicates that neither isoflavones nor soy proteins appear to have significant effects on hormonal levels in men with moderate intake (2-3 servings per day). In fact, the research found that consumption of soy foods is associated with a reduced risk of prostate cancer in men.

Does eating soy increase breast cancer risk?

Soy isoflavones can bind with estrogen receptors in the body and cause either weak estrogenic or anti-estrogenic activity. Harvard University indicates that these different actions may occur in the body based on species, hormone levels, and type of soy. Many human studies that followed a large population have shown potentially protective effects of soy foods against breast cancer. In the human body, plant-based estrogen-like compounds in soy products act as a protective substance by having a similar shape to real estrogens and taking their place, but not functioning the same. Therefore, consuming plant-derived isoflavones helps avoid the absorption of real estrogens and in turn, helps reduce the levels of estrogen in our bodies. Even for breast cancer survivors, it’s been shown that higher consumption of soy foods was significantly associated with a lower risk of death and recurrence.

Does soy lower the body’s ability to absorb certain nutrients?

With so many claims on blogs and social media suggesting we “avoid antinutrients,” many people are worried about the antinutrients in soy foods. These are substances that will bind certain nutrients and reduce the body’s ability to digest and absorb them. Antinutrients are natural compounds found in legumes, whole grains, nuts, seeds, and many vegetables. While it is true that soy contains various types of antinutrients (phytates, lectins, oxalates, saponins, etc.) that can negative effect different nutrient's bioavailability, they also have tons of positive effects. Some antinutrients have antioxidant and anti-inflammatory properties, and it’s been shown that they may have protective effects on heart disease and certain types of cancers. In addition, cooking, fermenting, and processing all help degrade antinutrients. In general, there is no evidence showing eating moderate amounts of soy causes any vitamins or minerals deficiencies.

Additional considerations

There are many different soy foods available in the market, including soybeans, tofu, edamame, tempeh, soy milk, miso, soy protein isolate, and soy-based meat substitutes. It’s worth noticing that not all soy products are equally beneficial and nutritious. In general, minimally processed soy foods (soybeans, edamame, tofu, and tempeh) tend to have more vitamins, minerals, and beneficial compounds than highly processed products (soy-based protein powders, mock meats, and energy bars). Therefore, it’s suggested to have whole food sources more often than processed soy products.

Learn more about plant-based eating and wellness programs offered by Wellness Workdays.

Written by Janet Lu, Wellness Workdays Intern



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