Soy is perfectly safe, as long as it’s prepared properly. Other preparations are… maybe. What I mean by that is this: According to Michael Pollan, author of In Defense of Food: An Eater’s Manifesto, Americans are eating soy for 1/5 of their diet. They are also eating soy in ways that Asians never used it; that is, fracturing it into soy isoflavones, soy protein isolate, textured vegetable protein (TVP), and making it into all manner of processed foods. It is these soy isoflavones that are estrogenlike compounds and bind to estrogen receptors, which is pretty much the reason people question how safe soy is to eat. It’s uncertain if the isoflavones are treated by the body as if they are estrogen, or if they fool the body into it, but the FDA has not granted soy GRAS status (Generally Recognized As Safe) because we’re just not sure how they work. According to the Linus Pauling Institute, the long term safety of eating soy isoflavones is unknown. Essentially, we need more data. However, for thousands of years, Asians have been eating soy and doing fine. Because it’s a staple in their diet, they’ve come up with some ways to make this food safe without necessarily meaning to, just because it was what they did with it in their culture. The traditional Asian diet incorporates soy in fermented form and as tofu. By boiling the crushed soy to form a kind of solution, and adding gypsum, they made curds (tofu) that are easily digestable. These foods have stood the test of time and aren’t as novel to the human body as what processors are doing to it nowadays. …Traditional fermented soy products such as miso, natto and tempeh-which are usually made with organically grown soybeans-have a long history of use that is generally beneficial when combined with other elements of the Oriental diet including rice, sea foods, fish broth, organ meats and fermented vegetables. Of course, as the VegHealthGuide reminds us, many things are OK to eat in moderation. “I’m aware of Internet paranoia on the subject of soy and the contention that only fermented soy is safe to consume. That is simply not true. Some of the best forms of soy – edamame, tofu and soy nuts – are unfermented and are much more likely to help you than hurt you. [..] All told, based on the evidence to date, I see no reason to worry about eating soy foods, whether fermented or not. I still recommend consuming one to two servings of soy per day, an amount equivalent to one cup of soy milk, or one half cup of tofu, soy protein (tempeh) or soy nuts.” — Dr. Andrew Weil, M.D. in “Rethinking Soy” Obviously, even the experts disagree. Perhaps becoming more informed about your food choices is the best possible answer. The preceeding was a reprint of my answer to a similar question in a different venue. So, why is tofu so popular? Because some soy is good for us. Also, it’s an alternative to meat, which isn’t exactly the best thing for us to eat all the time, either.