What Science Actually Says About Soy
- Rebecca Snyder
- Oct 12, 2020
- 2 min read
When I first went vegan, I remember being warned to be wary of soy because of the potential negative effects of its estrogens. Even to this day, I see posts in vegan Facebook pages about trying to limit soy for these same reasons. However, soy is otherwise a complete protein (meaning it has all of the amino acids that our bodies need from our diets), and legumes overall have been linked with increased health outcomes. Let’s dive into these claims and see if the research agrees that soy should be limited in a balanced, healthy diet.
First, the broad claim that estrogen intake is harmful fails to differentiate between the types of estrogens. While humans and other mammals produce mammalian estrogens, soy produces phytoestrogens. Phytoestrogen is just a fancy word for plant estrogens, but this is an important distinction to make because while phytoestrogens are similar to the estrogens that our bodies make, they do not work the same in our bodies. In fact, they have an antiestrogenic effect because they can block some receptors that our estrogens would normally use, negating their effects.
Because of this antiestrogenic effect, phytoestrogens from soy have actually been linked to lower rates of breast cancer, prostate cancer, kidney disease, and cardiovascular disease, along with lower cancer death rates and lower LDL (bad) cholesterol. For women who had breast cancer, the ones who ate soy not only had lower mortality rates, but also had lower recurrence rates, raising the possibility that soy may be beneficial rather than harmful!
While research suggests that phytoestrogens, such as those in soy, may lower estrogen levels slightly, it is interesting to note that a food product that does increase estrogen levels is cow’s milk. This makes sense when we think about how cows produce mammalian estrogens, therefore they have an effect on our bodies. Additionally, cow’s milk has been seen to lower testosterone levels. That’s not to say that you absolutely need to cut cow’s milk out of your diet. I just wanted to clarify that science says that soy does not have negative hormonal effects on our bodies with respect to estrogen levels! So, if this is something that you’re worried about or just generally want to make a healthy change, then direct your energy towards foods that are known to increase human estrogen levels, including cow's milk. The bottom line: current research indicates that you can enjoy your soy guilt-free.
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