The existence of brain gut microbiome interactions and the role of alterations in this regulatory system has clearly been established in a series of mouse models for anxiety, depression, autism spectrum disorders, Parkinson’s disease and multiple sclerosis. Recent studies have demonstrated that fecal transplant from human disease populations into gnotobiotic mice, can induce behavioral changes in these animals. However, definitive evidence for a causal role of the gut microbiome in human brain dysfunction remains to be established. Based on cross sectional studies, Emeran Mayer provides evidence for associations between gut microbial composition, brain parameters and behavioral measures in humans. Additionally, he demonstrates correlations between gut microbial architecture and function, food cravings and brain parameters in obesity and in irritable bowel syndrome. | Emeran A. Mayer ist Professor am Department für Medizin, Physiologie und Psychiatrie an der David Geffen School of Medicine, UCLA und derzeit Visiting Fellow am CAS.