Fig. 1: Intestinal epithelial cells metabolize dietary vitamin A into retinoic acid.
From: The role of retinoic acid in the production of immunoglobulin A
Dietary vitamin A is absorbed in human intestinal epithelial cells and processed via two enzymatic digestion steps. First, under normal physiological conditions, retinol is converted into retinal by microsomal retinol dehydrogenases (RDHs) in a reversible manner. Second, retinal is irreversibly converted by aldehyde dehydrogenases (ALDHs) into retinoic acid.
