Is Soy Really That Bad? What A Functional Food Expert Says

Whether or not soy is a healthy food has been hotly debated. While tofu and tempeh are complete proteins, making them some of the most effective plant-based alternatives to meat, many people worry that soy can negatively affect hormones. Functional food expert and spice aficionado Kanchan Koya, Ph.D., says that may not be the case. 

"Tofu (and soy) may be one of the most misunderstood foods out there," Koya writes in an Instagram post. Let's back up: Why are people so concerned about soy in the first place? 

Soybeans contain a bioactive compound called isoflavones. "Isoflavones belong to a class of compounds generally known as phytoestrogens, plant compounds that have estrogen-like structures1," states a review in the health journal Environmental Health Perspectives. Because of those estrogen-like structures, some people report having negative hormonal effects from eating soy.

That said, the research surrounding phytoestrogens and their role in the human body are pretty inconclusive. From Koya's perspective, there's nothing to be concerned about. "In actuality, the plant-based phytoestrogens in soy bind to our endogenous estrogen receptors differently than our own estrogen," Koya explains. In other words, the "estrogen-like" component may not interfere with human hormones at all.

On the other hand, there is some promising evidence that plant-based estrogen might be helpful for women going through menopause, who have low levels of estrogen, as a natural alternative to hormone replacement therapy (HRT). OB/GYN Maria Sophocles, M.D., FACOG, NCMP, tells mbg the estrogen-like compounds in soy2 may provide relief from hot flashes or vaginal dryness. However, the research is very limited, and more is necessary to draw a definite conclusion. 

Overall, soy in moderation likely won't hurt you, and it might even help. Beyond hormonal health, soy may be protective against cancer3 while also benefiting cardiovascular4 and bone health5, Koya writes. When fermented, soy may even support longevity.

To maintain the health benefits,6 she recommends sticking with no more than one to two servings per day (and opting for organic, when possible).