The volatile TMA crosses the intestinal barrier, is transported by the portal vein, and reaches the liver, where it is oxidized to TMAO by flavin-containing monooxygenase 3 (FMO3) [12] and FMO1 [13], two microsomal cytochromes whose transcription is modulated by bile acids and upregulated by cholestasis. Here, FMO3 is linked to cholestasis.