Influence of vegetable protein on gallstone formation in hamsters.

The lithogenic diet generally used for production of gallstones in hamsters contains 20% casein. In four separate experiments the 20% casein diet was compared with one containing 20% soy protein. All other components were kept constant. Two of the four experiments were of 45-day duration, one of 70 days and one of 100 days. When results of all four experiments were averaged, 57.5 +/- 3.6% of hamsters fed casein exhibited cholesterol gallstones whereas only 14.0 +/- 1.3% of soy protein-fed hamsters had gallstones. Thus, soy protein has a significant inhibitory effect on gallstone formation in hamsters. When soy protein was fed to hamsters with preestablished gallstones there was evidence of gallstone dissolution.