title: The effects of phytosterols present in natural food matrices on cholesterol metabolism and LDL-cholesterol: a controlled feeding trial.
abstract: OBJECTIVE
  Extrinsic phytosterols supplemented to the diet reduce intestinal cholesterol absorption and plasma low-density lipoprotein (LDL)-cholesterol. However, little is known about their effects on cholesterol metabolism when given in native, unpurified form and in amounts achievable in the diet. The objective of this investigation was to test the hypothesis that intrinsic phytosterols present in unmodified foods alter whole-body cholesterol metabolism.
  
  
  METHODS
  In all, 20 out of 24 subjects completed a randomized, crossover feeding trial wherein all meals were provided by a metabolic kitchen. Each subject consumed two diets for 4 weeks each. The diets differed in phytosterol content (phytosterol-poor diet, 126 mg phytosterols/2000 kcal; phytosterol-abundant diet, 449 mg phytosterols/2000 kcal), but were otherwise matched for nutrient content. Cholesterol absorption and excretion were determined by gas chromatography/mass spectrometry after oral administration of stable isotopic tracers.
  
  
  RESULTS
  The phytosterol-abundant diet resulted in lower cholesterol absorption (54.2±2.2% (95% confidence interval 50.5%, 57.9%) vs 73.2±1.3% (69.5%, 76.9%), P<0.0001) and 79% higher fecal cholesterol excretion (1322±112 (1083.2, 1483.3) vs 739±97 mg/day (530.1, 930.2), P<0.0001) relative to the phytosterol-poor diet. Plasma lathosterol/cholesterol ratio rose by 82% (from 0.71±0.11 (0.41, 0.96) to 1.29±0.14 μg/mg (0.98, 1.53), P<0.0001). LDL-cholesterol was similar between diets.
  
  
  CONCLUSIONS
  Intrinsic phytosterols at levels present in a healthy diet are biologically active and have large effects on whole-body cholesterol metabolism not reflected in circulating LDL. More work is needed to assess the effects of phytosterol-mediated fecal cholesterol excretion on coronary heart disease risk in humans.
authors.affiliation: Division of Endocrinology, Metabolism and Lipid Research, Department of Medicine, Washington University School of Medicine, 660 South Euclid Avenue, St Louis, MO 63110, USA.
authors.forename: X
authors.initials: X
authors.lastname: Lin
authors.forename: S B
authors.initials: SB
authors.lastname: Racette
authors.forename: M
authors.initials: M
authors.lastname: Lefevre
authors.forename: C A
authors.initials: CA
authors.lastname: Spearie
authors.forename: M
authors.initials: M
authors.lastname: Most
authors.forename: L
authors.initials: L
authors.lastname: Ma
authors.forename: R E
authors.initials: RE
authors.lastname: Ostlund
mesh_terms: D000924:Anticholesteremic Agents / Q000378:metabolism / Q000494:pharmacology*; D002784:Cholesterol / Q000097:blood / Q000378:metabolism*; D008078:Cholesterol, LDL / Q000097:blood / Q000378:metabolism*; D018592:Cross-Over Studies; D004032:Diet; D005260:Female; D005502:Food; D006801:Humans; D008297:Male; D008875:Middle Aged; D010840:Phytosterols / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D000924:Anticholesteremic Agents; D008078:Cholesterol, LDL; D010840:Phytosterols; C001521:lathosterol; D002784:Cholesterol
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