Abstract
Multiple Sclerosis (MS) is an autoimmune demyelinating disorder resulting from the interplay of genetic predisposition and environmental variables, including gut microbiota, diet and life style factors. Here, we first discuss the evidence supporting the effect of early life events, diet and body mass index on the composition of the microbiota, and then review studies on gut dysbiosis conducted in MS patients and in animal models. We address the effect of disease, immunomodulatory therapies, diet and probiotics on enrichment or depletion of gut microbial species. Finally, we discuss the ability of gut bacteria to produce toxins and metabolites which serve as signals for the cross-talk between the gut and the brain.