Absolute oral bioavailability and metabolic turnover of β-sitosterol in healthy subjects.

The metabolic turnover, absolute oral bioavailability, clearance, and volume of distribution for β-sitosterol were measured in healthy subjects. [(14)C]β-Sitosterol was used as an isotopic tracer to distinguish pulse doses from dietary sources and was administered by both oral and intravenous routes. The administered doses of [(14)C]β-sitosterol were in the region of 3 to 4 μg, sufficiently low as not to perturb the kinetics of β-sitosterol derived from the diet.