Reduction and esterification of cholesterol and sitosterol by homogenates of feces.

Mixtures of cholesterol-1,2-(3)H and sitosterol-4-(14)C have been incubated with suspensions of feces in order to compare the behavior of the phytosterol with transformations known to take place with cholesterol under these conditions. Within the limitations of the study, both labeled sterols were esterified to the same extent, and reduction of the Delta(5) double bond to the saturated analogue proceeded equally in both substances. After correcting for procedural losses, the recoveries of (3)H and (14)C from the incubations were always less than the controls; this strongly indicates destruction of sterol by feces microorganisms.