AHR and metabolic syndrome: In that line, administration of the AhR-ligand 6-formylindolo[3,2-b]carbazole (FICZ) or Lactobacillus reuteri, which has a high capacity to produce tryptophan-derived AhR-ligands, led to an improvement of the metabolic impairments in a mouse model with genetically-induced metabolic syndrome [17].