title: Gastrointestinal absorption and plasma kinetics of soy Delta(5)-phytosterols and phytostanols in humans.
abstract: Our objective was to measure the systemic absorption of lecithin-emulsified Delta(5)-phytosterols and phytostanols during test meals by use of dual stable isotopic tracers. Ten healthy subjects underwent two single-meal absorption tests in random order 2 wk apart, one with intravenous dideuterated Delta(5)-phytosterols and oral pentadeuterated Delta(5)-phytosterols and the other with the corresponding labeled stanols. The oral-to-intravenous tracer ratio in plasma, a reflection of absorption, was measured by a sensitive negative ion mass spectroscopic technique and became constant after 2 days. Absorption from 600 mg of Delta(5)-soy sterols given with a standard test breakfast was 0.512 +/- 0.038% for sitosterol and 1.89 +/- 0.27% for campesterol. The absorption from 600 mg of soy stanols was 0.0441 +/- 0.004% for sitostanol and 0.155 +/- 0.017% for campestanol. Reduction of the double bond at position 5 decreased absorption by 90%. Plasma t(1/2) for stanols was significantly shorter than that for Delta(5)-sterols. We conclude that the efficiency of phytosterol absorption is lower than what was reported previously and is critically dependent on the structure of both sterol nucleus and side chain.
authors.affiliation: Division of Endocrinology, Diabetes and Metabolism, Washington University School of Medicine, Missouri 63017, USA. Rostlund@im.wustl.edu
authors.forename: Richard E
authors.initials: RE
authors.lastname: Ostlund
authors.forename: Janet B
authors.initials: JB
authors.lastname: McGill
authors.forename: Chun-Min
authors.initials: CM
authors.lastname: Zeng
authors.forename: Douglas F
authors.initials: DF
authors.lastname: Covey
authors.forename: Jay
authors.initials: J
authors.lastname: Stearns
authors.forename: William F
authors.initials: WF
authors.lastname: Stenson
authors.forename: Curtis A
authors.initials: CA
authors.lastname: Spilburg
mesh_terms: D000328:Adult; D002784:Cholesterol / Q000031:analogs & derivatives* / Q000097:blood / Q000493:pharmacokinetics; D018592:Cross-Over Studies; D003903:Deuterium; D005260:Female; D006207:Half-Life; D006801:Humans; D007408:Intestinal Absorption; D007700:Kinetics; D008297:Male; D008875:Middle Aged; D010840:Phytosterols / Q000008:administration & dosage / Q000097:blood* / Q000493:pharmacokinetics*; D012855:Sitosterols / Q000097:blood / Q000493:pharmacokinetics; D013025:Glycine max / Q000737:chemistry*
chemical_list: D010840:Phytosterols; D012855:Sitosterols; C003535:campestanol; C021273:campesterol; C025473:gamma-sitosterol; D002784:Cholesterol; D003903:Deuterium