The human gut microbiome represents the collective genomes of a vast range of microorganisms, also referred to as the microbiota, which include bacteria, virus, archaea and protozoa, that together form an extremely complex ecosystem capable of communicating with the immune system and determining an individual’s predisposition to develop disease states. Manipulating the gut microbiome through dietary interventions, prebiotic and probiotic compounds and faecal microbiota transplantation may expand the therapeutic landscape in ulcerative colitis (UC). Specific diets, such as the Mediterranean diet or diet rich in omega-3 fatty acids, may reduce intestinal inflammation or potentially reduce the risk of incident UC.