No amount might be good for humans. Proven in lab animal studies, and proven "correlation studies" in humans. For thousands of years (5,000) chinese shunned ever eating soy and only allowed it in broken down form of "soy sauce" and "natto". Ancient texts warned chinese from eating soy beans, but they liked the effect of it in re-nitrogenating earth for other crops. Suddenly , in the late 1950s calcium modified denatured soy paste called TOFU became a trendy food stuff, and japanese and pacific rim and some chinese started eating tofu, but vegetarians and vegans overdo it, and the entire aisle in a supermarket, the entire isle of "VEGETARIAN PROCESSED FOODS" include textured soy for meat substitute in every damn item in the vegetarian aisle. Soy milk for a male is the kiss of death for testicles and brain alertness, but lots of (((scientists))) try to prevent a "causation" study and screech **"correlation is not causation**", or screech and kvetch that "lab animals are not human species! Reeeeeee!". Both points admittedly true, but a characteristic found in classic "jewish debate". I posted many links above. Studies abound. Most world populations that are vegetarian eat lots of milk products to avoid B12 brain damage, like all of india. Veganism is a genetic dead end for human survival without b12 vitamin supplements. Not one plant on earth creates b12. not one. Bacteria can generate b12, if you want to live on rotting compost.