Abstract: A method of treating severe mental diseases and related disorders or conditions includes administering to a patient in need thereof an effective amount of a composition including isoflavones and Bowman Birk Inhibitory Factor (BBIF). Preferably, the composition is a fermented soy composition. Preferably, one first diagnoses a patient with a particular mental disease or disorder, and then prescribes the composition as a treatment for the particular mental disease or disorder. A patient is preferably given daily a dosage of 3-10 mg of isoflavones and 5-10 Cl (chymotrypsin inhibitor) of BBIF per kg of body weight, more preferably a dosage of 5-9 mg of isoflavones and 5-10 CCl of BBIF per kg of body weight, and most preferably a dosage of 5-10 mg of isoflavones and 5-10 CCl of BBIF per kg of body weight. Treatment preferably lasts 7 days-14 days, or until all symptoms disappear.