Neutral steroid concentrations in the faeces of North American White and South African Black populations at different risks for cancer of the colon.

To test the hypothesis that a high risk for cancer of the colon might be associated with high concentrations of neutral steroids in the colon and with breakdown of these compounds by intestinal bacteria, the faecal neutral steroid concentrations of 84 rural South African Black adults (a population at low risk for colonic cancer), and of 98 North American White adults (a population at high risk for colonic cancer) were compared. Not only were the concentrations of animal steroids higher in the faeces of the North Americans, but the chemical state of their faecal steroids was different from that of the Blacks. A high proportion of plant and animal steroids in the faeces of the Blacks was esterified to long-chain fatty acids, whereas in the faeces of the North Americans, most of the neutral steroids were free (non-esterified). There was considerable variation in the extent of cholesterol metabolism by the intestinal bacterial in the North Americans. This was not the case with the South African population, which was much more homogeneous with respect to cholesterol metabolism.