soy.net

resources and information on soy^{(Copyright 2009 soy.net)}

Soy and many other edible legumes, seed grains, agave, buckwheat, etc., contains trypsin inhibitors (TI); Kunitz-type or Bowman Birk (protease) inhibitor (BBI).  Trypsin is an enzyme produced by the pancreas which aids in protein digestion.  TI content is all but deactivated during ordinary cooking, extrusion, etc., and is thereafter of no health consequence especially in processed soy with moderate intake.  Chronic, and very high intakes, of unprocessed soy could possibly cause pancreatitis from trypsin inhibition by causing the pancreas to oversecrete, but soybeans are as a rule never consumed raw.  Heat, fermentation and precipitation processing remove the vast majority of TI, over 90% are removed in the first 2 minutes of high pressure or heat processing.  As process methodology has improved it has been shown that the lowest quantities of TI are achievable and coincide with hypoallergenicity (removal of soy allergens).  Low level of BBI have been studied as chemopreventive agents themselves, shown to reverse preneoplastic foci to a greater extent than even isoflavones.  Oncogenicity studies have shown no histopathologic increases in either benign or malignant tumors in mice exposed to high test doses of BBI or a mix of soy isoflavones, whereas a control p-cresidine induced bladder cancers in both studies.  BBI is of high research value, currently being studied in the treatment of multiple sclerosis, muscle atrophy, and prostate cancer prevention (synergistically with isoflavones) and as anti-inflammatory agents.  A soybean Kunitz trypsin inhibitor suppressed ovarian cancer cell invasion by blocking urokinase upregulation.  In a colon carcinogenesis model in rats, both purified Bowman Birk Inhibitor and a soy extract thereof were effective in preventing colon cancer without adverse side effects.