Gut-oriented interventions in patients with multiple sclerosis: fact or fiction?

OBJECTIVE: Multiple sclerosis (MS) is a chronic, inflammatory, demyelinating, disimmune disease of the central nervous system whose etiology and pathogenesis remain poorly understood, due to its complex and multifactorial nature. Evidence of a bidirectional connection linking the gut microbiome with the intestinal barrier and the immune system (the gut-brain axis) may have implications for the pathogenesis of inflammatory demyelinating diseases such as MS. This narrative review summarizes the evidence for the gut-brain axis involvement in the pathogenesis of MS and examines the role of gut-oriented interventions in MS. PATIENTS AND METHODS: We reviewed all available studies in PubMed concerning gut-directed interventions and MS. This research was conducted using different combinations of pertinent keywords (multiple sclerosis, immune-mediated inflammatory diseases, autoimmune diseases, first demyelinating event, neurocognition, neurological disorders, neurology practice, risk factors, taxonomic biomarkers, nutrition, diet, dietary additives, complementary treatment, gut bacteria, gut microbiome, microbiome, gut-brain axis, epidemiology, alpha-linolenic acid, fermentative metabolites, fat, saturated fat, monounsaturated fat, polyunsaturated fat, omega-3 fatty acids, calorie restricted diet, fasting, fecal microbiome, fecal microbiota transplantation, animal testing). RESULTS: There is an emerging evidence that alterations in the gut microbiome and increased intestinal permeability may be causative factors in the complex interplay between nutrition, metabolic status and the immune-inflammatory response in patients with MS. This suggests the possibility that modification of lifestyle and the microbiome, for example by specific diets or fecal microbiota transplantation, supplementation with bile acids and intestinal barrier enhancers, may positively influence the pathogenesis of MS. CONCLUSIONS: Although the role of nutritional factors in the pathogenesis of MS remains to be established, there is evidence that appropriate gut-directed interventions such as diet, nutritional supplementation or fecal transplantation may modulate the inflammatory response and improve the course of MS as a complementary treatment in the disease.