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Of all the foods available in the modern American diet, the soybean may stand supreme for its versatile application in different dishes. Almost everyone, from the strictest vegan to the meat-loving omnivore, finds use and delight in this little plant product packed with protein. Despite its popularity, several myths have risen surrounding its effect on the human body. In this article, I will discuss these myths and further clarify how soy is in fact a wonderful contribution to your diet.
What are soybeans?
Soybeans are a type of legume, a bean pod native to East Asia, that are grown all over the world. The soybean is used to make a wide variety of products, including tofu, soy milk, soy sauce, natto, miso, and tempeh.
Your edamame at sushi restaurants is actually just the immature soybean pods that have been steamed or boiled. But soy’s most well-known use is as a vegan alternative, successfully crafted into plant-based milk, cheese, and even athletic supplement protein powder.
Nutrient packed soybeans
Aside from its versatility, soybeans possess an impressive nutrient profile compared to most other foods.
Foremost, it is protein-rich, probably the most excellent source of protein that can come from a plant. A single cup of boiled soybeans contains 29 grams of protein. This is only a few grams of protein less than beef or chicken.
Soy protein is also unique because of its complete amino acid profile. The human body needs 20 amino acids to thrive, and most proteins from grains or other legumes are usually missing some of these amino acids. But, not soy! It contains all 20, similar to meat and eggs.
Besides the protein content, soybeans stand out from other legumes because they are also a good source of calcium, iron, potassium, and magnesium. As a plant source, soy is also high in fiber and healthy fats compared to animal proteins.
Soybeans and phytic acid
Along with being one of the most frequently used foods in our diets, soy is also one of the most heavily researched foods we eat. Good thing too, because plenty of misconceptions exist concerning its impact on health.
For starters, critics of soybeans point to its high levels of phytic acids, plant compounds that can bind other nutrients. While it’s true that phytic acids can prevent the absorption of minerals in your diet, phytic acid content is highest in raw soybeans, and nobody eats soybeans raw.
Furthermore, simple practices such as cooking, soaking, grinding, and fermenting soy reduces the phytic acid levels and increases mineral availability – debunking this myth. You are unlikely to experience any nutrient impairment through soy intake. You can optimize nutrient intake by consuming a diverse diet with foods from many sources, including soy.
Soybeans and isoflavone
Most of the concern with soy revolves around its isoflavone content. Isoflavone is a naturally present compound that acts like a plant-derived version of estrogen, the same hormone predominant in women. Preliminary studies led to concerns that men who eat soy products will develop feminine features or experience infertility from elevated estrogen levels. This sounds troubling but it is absurd.
On the one hand, many clinical trials have demonstrated that normal isoflavone exposure does not impact estrogen levels in men. More importantly, the lab studies which produced these concerns were done in rats and mice, and rats and mice metabolize soy isoflavones differently than humans, disproving yet another myth about soy.
Soybeans and cancer
Chief among soy concerns is whether or not it contributes to cancer, specifically breast cancer. Since long term exposure to estrogen is a risk factor for breast cancer, and soy contains plant-based estrogens, it seemed like a reasonable concern.
Thankfully, numerous studies in a host of different settings have shown the opposite effect, that soy decreases the likelihood of cancer development. In a study of over 6,000 women with breast cancer, the women who consumed the most soy in their diets had the best outcomes from treatment. Additional evidence is emerging that soy may have other protective effects against other forms of cancer.
Soybeans and heart disease
Not only does the data show soy’s protective effects against cancer, but there are also other benefits to be had. The American Heart Association has concluded that soy products can be beneficial to cardiovascular health. Furthermore, soy appears to have a small but significant effect on lowering LDL cholesterol and blood pressure, two major contributors to heart disease.
To be fair, scientists are not yet sure if compounds in soy promote good health, or if the benefits come from replacing foods high in saturated fat with soy foods. Furthermore, there are inconsistencies in studies as to how much soy should be eaten and for how long to gain these benefits. Regardless, the science supports the safety of soy consumption in moderation. The applications and uses are near endless for incorporating this delicious bean into your diet. If you are interested in learning more about soy and your health, talk to a registered dietitian today!
Do you have any questions or thoughts about soybeans? Let us know in the comments below!
- Beaton LK, McVeigh BL, Dillingham BL, Lampe JW, Duncan AM. Soy protein isolates of varying isoflavone content do not adversely affect semen quality in healthy young men. Fertil Steril. 2010;94(5):1717-1722.
- Zhang, F.F., Haslam, D.E., Terry, M.B., Knight, J.A., Andrulis, I.L., Daly, M.B., … John, E.M. (2017). Dietary isoflavone intake and all-cause mortality in breast cancer survivors: The Breast Cancer Family Registry. Cancer, 123(11), 2070–2079. doi:10.1002/cncr.30615.
- Sacks, F.M., Lichtenstein, A., Van Horn, L., Harris, W., Kris-Etherton, P., & Winston, M. (2006). Soy Protein, Isoflavones, and Cardiovascular Health: An American Heart Association Science Advisory for Professionals From the Nutrition Committee. Circulation, 113, 1034-1044.