There is a lot of negative press about soy, soymilk, and tofu.
When I first became vegetarian I became very worried because I saw soybeans, soy milk, and tofu as really good sources of protein in my new plant-based diet. So I hit the Internets with my best research skills, a serving of critical thinking, and a healthy dose of skepticism.
I think my very first conclusion was that almost all of the bad press was due to sloppy reporting with a healthy measure of sensationalism. For instance, the man boob story was reported over and over again as evidence that too much soy was bad for you.
It didn't take me too long to find out that the man boob story was true. But it had only happened once. And the guy was not only obese but emotionally or mentally unstable. He was drinking quarts of soymilk every day. So here was a good example of both sloppy
and sensational reporting.
As I continued my research the next thing I found was that if you followed the citations references and citations just a little bit they all seemed to lead to the Wesson A. Price foundation. Dr. Price was a dentist, and as far as I can tell a pretty smart guy. But his foundation appears to have been suborned. Maybe by dairy industries. Not only do most anti-soy stories seem to have grown from WAP reporting - but many major scientific and medical have labeled his conclusions at least "questionable" and some have gone and labeled his conclusions dangerous propaganda.
One last myth I wanted to find out about. Over and over you hear the soy causes thyroid cancer and soy milk is not suitable for infant formula. I eventually gave up because some of the articles were over my head. but I did find one connection. Back in the '50s, in India, they did a small study on infant soymilk formulas. And one of the infants developed a thyroid issue. (not cancer!) It seems to me that this myth is so un-based in facts that I can't believe it still has legs. So there may be something else I couldn't figure out or discover. But just to further blow my mind, but the effects on infants' thyroids have never been replicated.
Just to touch a little of Luke's response. GMO soy is bad for the environment. They use tons of roundup to kill the weeds. The GMO soy is immune to Roundup. Then the round up washes down and into rivers, lakes, and oceans. Plus Monsanto who both makes the GMO Soy and roundup is just terribly unfair giant corp.
Then in the Amazon, they clear-cut forests to plant soy. The soy farms are unsustainable. Plus the harm to the environment and wildlife. But these soybeans are mostly exported to the USA as animal feed. KFC is the biggest importer.
Try as hard as you can to buy organic Non-GMO soy. And now the Trump administration's Tariff war is coming down on American Soy Farmers. (they export a lot of soy). So not only try to buy organic, non-GMO soy but try to buy North American grown soy.
One of the major soy milk makers, Silk, got bought up by a Big Four Food company. And I have my doubts about their soybeans. I've been avoiding them until I get some better reassurances.
References
http://www.whfoods.com/genpage.php?tname=foodspice&dbid=111
http://zenhabits.net/soy/
https://www.mensjournal.com/food-drink/does-soy-really-cause-man-boobs
https://sciencebasedmedicine.org/sbm-weston-prices-appalling-legacy/