title: Supplementation of test meals with fat-free phytosterol products can reduce cholesterol micellarization during simulated digestion and cholesterol accumulation by Caco-2 cells.
abstract: Phytosterols have been shown to reduce cholesterol absorption in humans. Supplementing phytosterols in fat-free formulations, however, has yielded controversial results. In the present study, we investigated the effect of supplementing test meals with different fat-free phytosterol products on cholesterol incorporation into mixed micelles during simulated digestion and accumulation of micellar cholesterol by Caco-2 cells: control orange juice (OJ), orange juice supplemented with either multivitamin/multimineral tablets (MVT), multivitamin/multimineral tablets containing phytosterols (MVT+P), and phytosterol powder (PP). These combinations were added to Ensure-based test meals and spiked with cholesterol of natural isotopic composition or 13C2-cholesterol to differentiate external from endogenous cholesterol. After simulated gastric/small intestinal digestion, micelle fractions were analyzed for cholesterol enzymatically (n = 6-20/product) and by high-performance liquid chromatography-tandem mass spectrometry (n = 12/product) and added to Caco-2 cells to determine the accumulation of 13C2-cholesterol (n = 10-24/product). As compared to OJ, PP and MVT+P significantly decreased cholesterol micellarization (determined enzymatically) by 70 +/- 39 (mean +/- SD) and 70 +/- 39%, respectively (P < 0.001, Bonferroni). The stable isotope experiments revealed that both PP and MVT+P reduced cholesterol micellarization [by 25 +/- 12 (P = 0.055) and 21 +/- 8% (P = 0.020), respectively, Fisher's protected LSD test] and Caco-2 cell accumulation (by 28 +/- 8 and 10 +/- 8%, respectively; P < 0.010, Bonferroni). OJ+P did not inhibit micellarization or accumulation of cholesterol by Caco-2 cells. This study shows that fat-free phytosterol-containing products can significantly inhibit cholesterol micellarization and Caco-2 cell bioaccessibility, albeit to different extents depending on individual formulations. This is most likely explained by inhibition of cholesterol micellarization.
authors.affiliation: Department of Food Science and Technology, Interdisciplinary Ph.D. Program in Nutrition, and Department of Human Nutrition, The Ohio State University, Columbus, Ohio 43210, USA. torsten.bohn@gmx.ch
authors.forename: Torsten
authors.initials: T
authors.lastname: Bohn
authors.forename: Qingguo
authors.initials: Q
authors.lastname: Tian
authors.forename: Chureeporn
authors.initials: C
authors.lastname: Chitchumroonchokchai
authors.forename: Mark L
authors.initials: ML
authors.lastname: Failla
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Schwartz
authors.forename: Richard
authors.initials: R
authors.lastname: Cotter
authors.forename: Joel A
authors.initials: JA
authors.lastname: Waksman
mesh_terms: D018938:Caco-2 Cells; D002784:Cholesterol / Q000737:chemistry / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D019587:Dietary Supplements; D004063:Digestion; D006801:Humans; D013058:Mass Spectrometry; D008823:Micelles; D008954:Models, Biological; D010840:Phytosterols / Q000008:administration & dosage*; D014815:Vitamins / Q000008:administration & dosage
chemical_list: D008823:Micelles; D010840:Phytosterols; D014815:Vitamins; D002784:Cholesterol