Different mechanisms of how vitamin D impacts on stress reactivity and pathophysiology of psychiatric disorders have been proposed: After activation of 25(OH)D to 1,25(OH)D by the 1α‐hydroxylase, vitamin D binds to intracellular vitamin D receptors (Holick, 2007), which subsequently occupy vitamin D response elements around promotor regions of different genes (Uitterlinden et al., 2004). Here, VDR is linked to psychiatric disorder.