Differential effect of dietary antioxidant classes (carotenoids, polyphenols, vitamins C and E) on lutein absorption.

Lutein is assumed to protect the human retina from blue light and oxidative stress and diminish the incidence of age-related macular degeneration. This antioxidant is commonly ingested with other dietary antioxidants. The aim of the present study was to assess whether the main dietary antioxidants, i.e. carotenoids, polyphenols and vitamins C and E, affect lutein absorption. We measured the effect of adding a mixture of antioxidants (500 mg vitamin C, 67 mg (100 IU) vitamin E and 1 g polyphenols) to a lutein-containing meal (18 mg) on the postprandial lutein response in the chylomicron-rich fraction in eight healthy men. Lutein response was weakest (-23 %; P=0 x 07) after ingestion of the meal containing antioxidants (21 x 9 (sem 4 x 6) v. 28 x 4 (sem 7 x 2) nmol x h/l). To assess the effect of each class of antioxidants and potential interactions, we subsequently evaluated the effect of various combinations of antioxidants on lutein uptake by human intestinal Caco-2 TC-7 cells. A full factorial design showed that both a mixture of polyphenols (gallic acid, caffeic acid, (+)-catechin and naringenin) and a mixture of carotenoids (lycopene plus beta-carotene) significantly (P<0 x 05) impaired lutein uptake by (-10 to-30 %), while vitamins C and E had no significant effect. Subsequent experiments showed that the aglycone flavanone naringenin was the only polyphenol responsible for the effect of the polyphenol mixture, and that the carotenoid effect was not carotenoid species-dependent. Taken together, the present results suggest that lutein absorption is not markedly affected by physiological concentrations of vitamins C and E but can be impaired by carotenoids and naringenin