"Soy" is not
fermented soy. Traditionally, humans ate fermented soy ONLY, and unfermented soy was fed to animals. The soy everyone has a problem with these days is unfermented, ground into a liquid and sprayed into a drying drum. It's only fit for animals - but now it's in everything. Many, many people are allergic to it, it causes histamine reactions and can literally kill some people. It's common as meat fillers.
Natto is fermented. Whole different thing, very healthy.
+ about a million. Well said.
Unfermented soy is pretty toxic. Fermented soy is extremely good for you.