Carotenoid basics: from food to skin

The aim of this review is to provide a comprehensive and simple graphical overview on carotenoids. The review describes in four detailed figures the course of carotenoids from food to skin. Differences in chemical structures of the six most prominent carotenoids, namely, α-carotene, β-carotene, lutein, zeaxanthin, lycopene and β-cryptoxanthin, and their seasonal variations in plasma concentrations resulting from different availability of fruits and vegetables are highlighted. Furthermore, factors affecting carotenoid status, sites of storage and how and where they can be assessed (dietary intake and in vivo) are discussed. The route of carotenoid transport after ingestion, transport across the enterocyte and receptors involved in carotenoid uptake in peripheral cells are shown followed by the routes of carotenoid delivery to the skin and reasons for variations in skin carotenoid status are visualized.