Q. Are fermented soyfoods better for you than other soyfoods?
A. Assuming you aren't allergic, foods made from soy can add a lot to your diet, and fermented soyfoods have even more going for them. Many unfermented soy products (such as yogurt, ice cream, and soy "sausage" or "bacon") are relatively new additions to our food supply; others such as soymilk and edamame (boiled whole soybeans) are more traditional. Nearly all fermented soyfoods (such as tempeh, natto, miso, and shoyu, or tamari) have been enjoyed in Asian countries for many centuries.
Why are fermented soyfoods especially beneficial? Perhaps most important, the fermentation process results in better digestibility and absorption of the isoflavones. In addition, studies show that fermented soyfoods help lower blood pressure and cholesterol just as well as unfermented soyfoods, and they bestow even greater cancer protection (Hypertension Research, 2006, vol. 29, no. 9; Nutrition, 2006, vol. 22, no. 5).
Last but not least, there's a pragmatic benefit for those around you: less flatulence. Soy's natural, gas-forming oligosaccharide content gets reduced during the fermentation process. So go ahead and go crazy with that miso soup!.
This Q&A was written by Victoria Dolby Toews, MPH, author of the The Soy Sensation (McGraw-Hill, 2002) and The Green Tea Book (Avery, 1998).