Role of fiber in IBS
Although increasing dietary fiber continues to be a standard recommendation for patients with IBS, clinical practice has shown that increased fiber intake in these patients increases abdominal pain, bloating, and distention. IBS patients assigned to fiber treatment showed persistent symptoms or no improvement in symptoms after treatment compared with patients taking a placebo or a low-fiber diet. Other studies have shown that although water-insoluble fiber intake did not improve IBS symptoms, soluble-fiber intake was effective in improving overall IBS symptom. It is noteworthy that the role of FODMAPs and fiber on IBS symptoms is associated with intestinal flora. The presence of bacteria that break down FODMAPs and fiber and produce gas, such as Clostridia spp., can cause distention of the large intestine with abdominal discomfort or pain.