INS and major depressive disorder: All of the studies recruiting patients with a diagnosis of depression (Akkasheh et al., 2016; Chahwan et al., 2019; Pinto‐Sanchez et al., 2017) analyzed inflammatory biomarkers after the probiotic treatment, but only one of them, (Akkasheh et al., 2016) which included a population with a diagnosis of MDD, demonstrated an improvement of some inflammation‐related parameters and insulin metabolism.