Gastrointestinal absorption and plasma kinetics of soy Δ5-phytosterols and phytostanols in humans

Richard E. Ostlund, Janet B. McGill, Chun Min Zeng, Douglas F. Covey, Jay Stearns, William F. Stenson, Curtis A. Spilburg

Research output: Contribution to journalArticlepeer-review

240 Scopus citations


Our objective was to measure the systemic absorption of lecithin-emulsified Δ5-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 Δ5-phytosterols and oral pentadeuterated Δ5-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 Δ5-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 t1/2 for stanols was significantly shorter than that for Δ5-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.

Original languageEnglish
Pages (from-to)E911-E916
JournalAmerican Journal of Physiology - Endocrinology and Metabolism
Issue number4 45-4
StatePublished - 2002


  • Campestanol
  • Campesterol
  • Cholesterol
  • Clinical study
  • Deuterium
  • Diet
  • Mass spectrometry
  • Sitostanol
  • Sitosterol


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