Carotenoid interactions

Interactions between carotenoids during absorption and during postabsorptiv e metabolism have been demonstrated or suggested in animal and human feedin g or supplementation studies, as well as in in vitro studies of intestinal beta-carotene cleavage. Much of the evidence suggests an interaction betwee n beta-carotene and oxycarotenoids such as canthaxanthin and lutein, and be tween the hydrocarbon carotenoids beta-carotene and lycopene. The evidence is equivocal, however, with discrepant findings between studies, both in ma gnitude and in direction of the interactions observed. This review discusse s studies of carotenoid interactions and explores the possible underlying m echanisms and implications of these interactions. The most likely explanati ons for carotenoid interactions appear to be competition for incorporation into micelles, carotenoid exchange between lipoproteins in the postprandial state, and inhibition of provitamin A (beta-carotene) cleavage.