Soy
Soy contains protease inhibitors, which frustrate the body's digestion of protein.
Soy (and many other grains, as well) contains phytic acid, which acts like a magnet for many important minerals, such as calcium, magnesium, zinc, and iron, therefore preventing their absorption into the body.
Asian cultures have historically eaten soy primarily in its fermented forms: miso, tempeh, soy sauce, and tamari which significantly lessens the protease inhibitors and phytates in soy, almost to the point of elimination. Tofu, eaten sparingly, is the only non-fermented form of soy that has been historically common in Asian cultures.
Soy (and many other grains, as well) contains phytic acid, which acts like a magnet for many important minerals, such as calcium, magnesium, zinc, and iron, therefore preventing their absorption into the body.
Asian cultures have historically eaten soy primarily in its fermented forms: miso, tempeh, soy sauce, and tamari which significantly lessens the protease inhibitors and phytates in soy, almost to the point of elimination. Tofu, eaten sparingly, is the only non-fermented form of soy that has been historically common in Asian cultures.