Soybeans contain several growth inhibitors that are heat labile and may be removed or deactivated by heat treatment. The chief of these growth inhibitors was believed, in the past, to be trypsin. Trypsin is a proteolytic enzyme necessary in digestion to catalyze the synthesis of amino acids in the digestive tract. Raw soybeans do not promote growth in animal with short digestive systems, but the trypsin inhibitor is now considered to be a minor problem. Soybean hemagglutinin, the toxic component of the crude inhibitor, is also heat labile. Liener (1973, lists five additional heat labile protease inhibitors: Saponin, a goitrogenic factor, an anticoagulant factor, the diuretic principle, and lipoxidase.