title: Absolute oral bioavailability and metabolic turnover of β-sitosterol in healthy subjects.
abstract: 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. Because the plasma concentrations of [(14)C]β-sitosterol arising from such low doses were anticipated to be very low, the ultrasensitive isotope ratio analytical method of accelerator mass spectrometry was used. The limit of quantification for [(14)C]β-sitosterol was approximately 0.1 pg/ml, the oral absolute bioavailability was just 0.41%, clearance was 85 ml/h, volume of distribution was 46 L, and the turnover was 5.8 mg/day. Given the steady-state concentrations of β-sitosterol (2.83 μg/ml), then the dietary load was calculated to be approximately 1400 mg/day.
authors: Unilever R&D, Vlaardingen, The Netherlands. guus.duchateau@unilever.com
authors: Guus
authors: G
authors: Duchateau
authors: Brett
authors: B
authors: Cochrane
authors: Sam
authors: S
authors: Windebank
authors: Justyna
authors: J
authors: Herudzinska
authors: Davindera
authors: D
authors: Sanghera
authors: Angela
authors: A
authors: Burian
authors: Markus
authors: M
authors: Müller
authors: Markus
authors: M
authors: Zeitlinger
authors: Graham
authors: G
authors: Lappin
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D019540:Area Under Curve; D001682:Biological Availability; D001711:Biotransformation; D002250:Carbon Radioisotopes; D004032:Diet; D006207:Half-Life; D006801:Humans; D000960:Hypolipidemic Agents / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics*; D007275:Injections, Intravenous; D008297:Male; D013058:Mass Spectrometry / Q000379:methods; D008657:Metabolic Clearance Rate; D008875:Middle Aged; D008954:Models, Biological; D012855:Sitosterols / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics*; D055815:Young Adult
chemical_list: D002250:Carbon Radioisotopes; D000960:Hypolipidemic Agents; D012855:Sitosterols; C025473:gamma-sitosterol