Psyllium Fiber Reduces Abdominal Pain in Children With Irritable Bowel Syndrome in a Randomized, Double-Blind Trial

BACKGROUND & AIMS: We sought to determine the efficacy of psyllium fiber treatment on abdominal pain and stool patterns in children with irritable bowel syndrome (IBS). We evaluated effects on breath hydrogen and methane production, gut permeability, and microbiome composition. We also investigated whether psychological characteristics of children or parents affected the response to treatment. METHODS: We performed a randomized, double-blind trial of 103 children (mean age, 13 +/- 3 y) with IBS seen at primary or tertiary care settings. After 2 weeks on their habitual diet, children began an 8-day diet excluding carbohydrates thought to cause symptoms of IBS. Children with >= 75% improvement in abdominal pain were excluded (n = 17). Children were assigned randomly to groups given psyllium (n = 37) or placebo (maltodextrin, n = 47) for 6 weeks. Two-week pain and stool diaries were compared at baseline and during the final 2 weeks of treatment. We assessed breath hydrogen and methane production, intestinal permeability, and the composition of the microbiome before and after administration of psyllium or placebo. Psychological characteristics of children were measured at baseline. RESULTS: Children in the psyllium group had a greater reduction in the mean number of pain episodes than children in the placebo group (mean reduction of 8.2 +/- 1.2 after receiving psyllium vs mean reduction of 4.1 +/- 1.3 after receiving placebo; P = .03); the level of pain intensity did not differ between the groups. Psychological characteristics were not associated with response. At the end of the study period, the percentage of stools that were normal (Bristol scale scores, 3-5), breath hydrogen or methane production, intestinal permeability, and microbiome composition were similar between groups. CONCLUSIONS: Psyllium fiber reduced the number of abdominal pain episodes in children with IBS, independent of psychological factors. Psyllium did not alter breath hydrogen or methane production, gut permeability, or microbiome composition.