Effect of the main dietary antioxidants (carotenoids, γ-tocopherol, polyphenols, and vitamin C) on α-tocopherol absorption

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 24mg 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/lh vs 1001 +/- 287 nmol/lh). The observed extent of reduction ( - 38%, P = 0.069) supported the inhibitory effect of carotenoids observed in the Caco-2 experiments. Conclusion: Naringenin, carotenoids and probably gamma-tocopherol can impair alpha-tocopherol absorption whereas vitamin C and phenolic acids have no effect.