[Irritable Bowel Syndrome, Emotion Regulation, and Gut Microbiota]

Irritable bowel syndrome (IBS) is defined as a representative functional gastrointestinal disorder which is characterized by chronic or recurrent abdominal pain and/or abdominal discomfort associated with abnormal bowel movement. Gut microbiota are related to the pathophysiology of IBS. In the field of IBS, post-infectious etiology, stress-induced alteration of microbiota, increased mucosal permeability, bacterial overgrowth, disease-specific microbiota, microbial products, and brain-gut interactions are being investigated. In some individuals, IBS develops after recovery from acute gastroenteritis known as post-infectious IBS. Gut microbiota in IBS patients differ from those in healthy individuals, and the profiles of gut microbiota in IBS patients also vary among IBS patients with constipation, diarrhea, and mixed subtypes. In Japan, gut microbiota in IBS patients also differ from those observed in healthy individuals, and organic acid by-products observed in the patients correlated with symptoms, quality of life, and alexithymia. Further research on gut microbiota in IBS patients is warranted.