Bile acid concentrations, cytotoxicity, and pH of fecal water from patients with colorectal adenomas

In the multistage model of human colorectal tumorigenesis, both genetic and environmental factors play an important role, The identity of the environm ental factors involved, however, still remains to be elucidated. As fecal b ile acids are proposed as candidates, we compared the concentration of bile acids in fecal water from patients at different risk of developing colorec tal cancer. In addition, pH of fecal water as well as its cytotoxicity to H T-29 colonic cells was determined. The high-risk group consisted of individ uals diagnosed with one or more (tubulo)villous colorectal adenomas larger than 1 cm in diameter and containing moderate or severe dysplasia (N = 20), Subjects with colorectal adenomas smaller than 1 cm and showing only minor dysplasia were assigned to the medium risk group (N = 19), The control gro up consisted of persons with normal findings by colonoscopy (N = 25), The r esults show no significant differences in fecal water bile acid concentrati ons between the three groups. However,46% of the observed cytotoxicity is e xplained in a regression model that includes pH and the concentrations of d eoxycholic acid, cholic acid, and ursodecaxycholic acid. The pH of fecal wa ter is found to be significantly lower in the high risk group as compared t o the controls, suggesting that a relatively high fecal pH has a protective effect on the development of colorectal adenomas. Although hyperproliferat ion as a result of cytotoxicity has been suggested to contribute to tumor f ormation in the colon, the pH-dependent cytotoxicity of bile acids in fecal water was not found to be associated with adenoma formation in the present study.