Trypsin inhibitor content of soy protein
isolate can vary as much as fivefold.21 (In rats, even low - level - trypsin - inhibitor SPI feeding results in reduced
weight gain compared to controls.22) But high - temperature processing has the unfortunate side effect of so denaturing the other proteins in soy that they are rendered largely ineffective.23 That's why animals on soy feed need lysine
supplements for normal growth.