IDO2 and Abnormal emotional state: DR7 supplementation reduced symptoms of stress, anxiety, and psychological distress in stressed adults.DR7 reduced plasma cortisol and pro-inflammatory cytokines and increased anti-inflammatory cytokines.DR7 administration was associated with lowered expression of plasma dopamine β-hydroxylase, tyrosine hydroxylase, indoleamine 2,3-dioxygenase, and tryptophan 2,3-dioxygenase and increased expression of tryptophan hydroxylase-2 and 5-hydroxytryptamine receptor-6.