Distinct pathways for the absorption and metabolism of β-carotene and zeaxanthin in the mouse intestine.

Carotenoids, essential nutrients for eye health, are absorbed in the intestine to support vitamin A homeostasis and provide cellular protection. This process involves the lipid transporters scavenger receptor class B type 1 (SR-B1, encoded by Scarb1 gene) and Niemann-Pick C1-Like 1 (NPC1L1), which load these dietary lipids into the plasma membrane of intestinal enterocytes. However, the precise contribution of these transporters to carotenoid absorption, the putative involvement of Aster proteins in their downstream movement, and the interactions with their metabolizing enzymes, β-carotene oxygenase 1 (BCO1) and β-carotene oxygenase 2 (BCO2), remain incompletely understood.