Two patterns of neutral steroid conversion in the feces of normal North Americans.

It has been suggested by other investigators that the extent of neutral and acid steroid conversion by human intestinal flora may be correlated with large-bowel carcinogenesis. Within a population of 31 normal North Americans, we found that two distinct patterns of neutral steroid conversion could be detected by gas-liquid Chromatographie procedures. One pattern was characterized by extensive conversion of choles terol, the other by little or no conversion of cholesterol. Similar conversion patterns were also observed for the plant steroids, sitosterol and campesterol. These patterns were found to be relatively stable over long periods of time. It is possible that there may be differences in the risk level for colon cancer between these two groups.