If you’ve been following the latest nutrition trends, you’ve likely heard a few of the claims about soy. Some say it decreases sperm count and increases breast cancer risk. Others say there’s no concern and it’s beneficial for heart health. With all these opposing claims, it’s no wonder soy has become such a point of contention!
At our upcoming Nutrition Myths class on December 4, we’ll be exploring soy in more detail, along with a few other controversial topics. Yet, we had so much fun digging into the research, that we couldn’t resist sharing a bit of what we found with you on the blog today!
What is Soy?
From tofu to miso and soybean oil to soy protein isolate, there are numerous forms of the soybean. Soybeans are part of the legume family and in their whole form, they provide a mix of protein, fat, carbohydrates, and fiber. Additionally, soybeans also serve as a great source of calcium and iron.
So what’s the problem? Some argue that the minerals found in soybeans (and other legumes and grains) are not bioavailable due to the presence of compounds called “anti-nutrients,” such as phytates. However, there are numerous ways to reduce phytate content, such as soaking and cooking. Sprouting and fermenting, which often accompany traditional methods of preparing soybeans (tempeh and miso, anyone?), also activate an enzyme called phytase that can significantly reduce phytate activity.
Phytoestrogens in Soy
Anti-nutrients aside, the main reason why soy has become controversial is because of its phytonutrient content. Phytonutrients are compounds found in plants that offer biological activity within the body. Soybeans contain two specific phytonutrients—genistein and daidzein—that are classified as phytoestrogens (PEs). This is where much of the concern around soy comes from, as PEs are structurally similar to estrogens and have the ability to bind to estrogen receptors within the body.
At first glance, this would appear concerning. However, the amount of PEs needed to exert an unfavorable influence on hormone levels is much higher than what most individuals typically consume through their regular diet.
Whole vs. Processed Soy
The form of soy is also important. Each type of soy-based food (tofu, soy protein isolate, edamame, soy sauce, etc.) contains a different amount of PEs. Processed forms of soy, such as soy protein isolate and soy protein concentrate, tend to contain higher amounts of PEs. While these isolated and processed forms of soy may pose a concern, soy consumed in its whole form appears to provide benefit against various chronic diseases. In fact, individuals in countries where soybeans are a regular part of the diet tend to have lower rates of cancer and cardiovascular disease.
The benefit likely comes from the synergistic effect of eating soy in its whole food form, such as edamame, miso, and tempeh. Along with genistein and daidzein, soybeans also contain a variety of other phytonutrients that provide antioxidant and anti-inflammatory benefits. The synergy of the different vitamins, minerals, and phytonutrients working together is likely what contributes to the protective benefits seen in soy.
This is just a taste of the soy discussion, and we’ll be diving deeper into the relationship between soy and cancer, testosterone, fertility, and thyroid function in our December 4 Nutrition Myths class. You can learn more and register for the class online—hope to see you there!