Strong evidence suggests that gut microbiota has an important role in bidirectional interactions between the gut and the nervous system. It interacts with CNS by regulating brain chemistry and influencing neuro-endocrine systems associated with stress response, anxiety and memory function. Many of these effects appear to be strain-specific, suggesting a potential role of certain probiotic strains as novel adjuvant strategy for neurologic disorders. In addition, the effects of CNS on microbiota composition are likely mediated by a perturbation of the normal luminal/mucosal habitat that can also be restored by the use of probiotics and possibly by diet. In clinical practice, in particular IBS, now considered a microbiome-GBA disorder.