title: Effect of the main dietary antioxidants (carotenoids, gamma-tocopherol, polyphenols, and vitamin C) on alpha-tocopherol absorption.
abstract: OBJECTIVE
  (R,R,R)-alpha-tocopherol is a fat-soluble antioxidant vitamin generally ingested with other dietary antioxidants. The objective of this study was to assess whether the main dietary antioxidant classes, that is carotenoids, polyphenols, vitamin C and gamma-tocopherol, affect the intestinal absorption of alpha-tocopherol. METHODS, DESIGN AND SUBJECTS: We evaluated first the effect of different combinations of antioxidants on (R,R,R)-alpha-tocopherol absorption by a human intestinal cell line (Caco-2 clone TC7). Then we compared the effect of two doses of a dietary antioxidant (lutein) on the postprandial chylomicron alpha-tocopherol responses to an alpha-tocopherol-rich meal. Eight healthy men ate two similar meals in a random order at a 1 month interval. The meals contained 24 mg alpha-tocopherol in sunflower oil plus either 18 or 36 mg lutein. Blood samples were collected during the postprandial periods to compare chylomicron alpha-tocopherol responses.
  
  
  RESULTS
  A mixture of polyphenols (gallic acid, caffeic acid, (+)-catechin and naringenin) and a mixture of carotenoids (lycopene, beta-carotene and lutein) significantly impaired alpha-tocopherol absorption in Caco-2 cells (P<0.001 and P<0.0001, respectively). The inhibitory effect of gamma-tocopherol was close to significance (P=0.055). In contrast, vitamin C had no significant effect (P=0.158). Naringenin was the only polyphenol that significantly impaired alpha-tocopherol absorption. Postprandial alpha-tocopherol response was weakest at the highest dose of lutein (616+/-280 nmol/l h vs 1001+/-287 nmol/l h). The observed extent of reduction (-38%, P=0.069) supported the inhibitory effect of carotenoids observed in the Caco-2 experiments.
  
  
  CONCLUSIONS
  Naringenin, carotenoids and probably gamma-tocopherol can impair alpha-tocopherol absorption whereas vitamin C and phenolic acids have no effect.
authors.affiliation: INSERM, U476 Nutrition Humaine et Lipides, Marseille, France.
authors.forename: E
authors.initials: E
authors.lastname: Reboul
authors.forename: S
authors.initials: S
authors.lastname: Thap
authors.forename: E
authors.initials: E
authors.lastname: Perrot
authors.forename: M-J
authors.initials: MJ
authors.lastname: Amiot
authors.forename: D
authors.initials: D
authors.lastname: Lairon
authors.forename: P
authors.initials: P
authors.lastname: Borel
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000494:pharmacology*; D019540:Area Under Curve; D001205:Ascorbic Acid / Q000494:pharmacology; D018938:Caco-2 Cells; D002338:Carotenoids / Q000494:pharmacology; D002914:Chylomicrons / Q000737:chemistry*; D018592:Cross-Over Studies; D004305:Dose-Response Relationship, Drug; D005419:Flavonoids / Q000494:pharmacology; D006801:Humans; D007408:Intestinal Absorption / Q000187:drug effects*; D014975:Lutein / Q000494:pharmacology*; D008297:Male; D010636:Phenols / Q000494:pharmacology; D059808:Polyphenols; D019518:Postprandial Period; D024502:alpha-Tocopherol / Q000493:pharmacokinetics*; D024504:gamma-Tocopherol / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D002914:Chylomicrons; D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols; D002338:Carotenoids; D024504:gamma-Tocopherol; D024502:alpha-Tocopherol; D001205:Ascorbic Acid; D014975:Lutein