Fig. 1

Vitamin A Biosynthesis and Activation. This figure represents a schematic presentation for the activation process of β-carotene to retinol in the small intestine following the absorption of the β-carotene from t;9he apical membrane and then the transportation of the activated retinol via the basolateral membrane directed towards the liver via chylomicrons. In the liver, it is processed in a trimolecular complex that is made up of active retinol, retinol-binding protein, and transthyretin protein. Such trimolecular complex prevents its glomerulus filtration via the kidneys