Classic nutrition believed that healthy diets should simply provide sufficient antioxidant loads to organisms, to hamper free radical processes and avoid oxidative stress. Current redox biology was proven much more intricate. Carotenoids are bioactive compounds in the human diet with a multifaceted role in redox metabolism. This perspective discusses the participation of α/β-carotene, lutein, zeaxanthin, lycopene, β-cryptoxanthin, astaxanthin, and derivatives in redox homeostasis focusing on (i) their antioxidant/pro-oxidant activities, (ii) control of gene expression via Nrf2-Keap1 and NF-κB pathways, and (iii) their link with (sub)cellular redox circuits, as part of the "redox code" that orchestrates physiological processes and health in humans.
Keywords: Nrf2; antioxidant; apocarotenoid; apoptosis; free radicals; inflammation; oxidative stress; redox switch.