In Japan, we eat soy all the time. For breakfast we have rice with natto and miso soup with tofu; for dinner we pop edamame into our mouths in between chopsticks-full of vegetables sauteed in soy sauce. I always assumed it was good for you, until I came to California and my health-conscious American friend told me that soy was actually really bad for you. So which is it?
Here's what we know about soy: unprocessed, it's a great source of digestible protein and has tons of vitamin B, calcium, and folate — all things that are good for you. It also contains isoflavones, and here's where things get tricky. Some studies prove that isoflavones are beneficial, while others have shown that it promotes breast and prostate cancer. Soy has also been called out as an agent of brain cell aging and thyroid dysfunction, too.
In her recent book The Jungle Effect, San Francisco-based physician Daphne Miller — who studied low cancer rates in Okinawa extensively — writes:
While Okinawans take in over 80 percent of their soy in a relatively unprocessed form as tofu, edamame, soy flour, soy milk, or miso, people in the United States eat a similiar percentage of their soy in a processed form. Our soy foods are heated, mashed, and denatured to create a vast array of substances ranging from Tofurky to fillers for tuna fish to ice-cream sandwiches... while whole foods offer valuable protection, concentrated or denatured derivatives of these foods are having the opposite effect.
The bottom line, at least for now, seems to be that good soy prevent cancer and bad soy might promote cancer. Good soy = tofu, soy sauce, miso, natto, edamame. Bad soy = soy protein powder, energy bars made with soy, fake hot dogs, tofurky.
A lot of Western people think natto — fermented soy bean — is gross because of it's gooey texture and stinky smell, but it's one of my favorite things to eat for breakfast. It's filled with protein and great for a post-workout snack, too. If you're still iffy about it, why not combine the foreign with the familiar and cook some natto spaghetti? The slippery texture of the pasta cuts the gooeyness a little, and in my opinion this is a gentle way to ease natto into your culinary life.
Every installment of Taste Test will explore recipes, the science, and some history behind a specific food item.