Are soybeans toxic unless they're fermented?

1 answer | Last updated: Oct 17, 2016
Wallace asked...

I heard soybeans were toxic if eaten, unless they were fermented. Is there anything to this??


Expert Answers

Beth Reardon, M.S., R.D., L.D.N., is Caring.com senior food and nutrition editor and the director of integrative nutrition at Duke Integrative Medicine. As a practitioner of integrative nutrition, Reardon takes a holistic approach to wellness, recognizing that the foundation for optimal health and healing begins with a health-promoting diet. As a practitioner of integrative nutrition, Reardon takes a holistic approach to wellness, recognizing that the foundation for optimal health and healing begins with a health-promoting diet.

Soybeans, in their raw unfermented state do contain a number of compounds, referred to as "anti- nutrients", that have been found in mice studies to be toxic when consumed in high amounts. Included among them are enzyme inhibitors that block the action of enzymes needed for protein digestion; phytates that bind and inhibit the body's absorption of calcium, and goitrogens, compounds that may interfere with thyroid function in certain populations. If consumed in large quantities over a long period of time any of these could be problematic. Soybeans however are not consumed in their raw form and are typically eaten steamed, roasted, boiled, fermented or otherwise processed. Fermented, non GMO, whole soy foods contain the most health benefits and the fermentation process along with cooking, reduces or eliminates many of these harmful compounds. Fermented soy products include tempeh, natto, and miso.