Efficacy of a low-FODMAP diet in children with irritable bowel syndrome and functional abdominal pain-not otherwise specified: a randomized controlled trial with early termination.

Objective: Evidence supporting the effectiveness of a low fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (low-FODMAP) diet in treating functional abdominal pain disorders remains limited. We aimed to assess the efficacy of a low-FODMAP diet compared with a regular diet for management of children with irritable bowel syndrome (IBS) and functional abdominal pain-not otherwise specified (FAP-NOS). Methods: This randomized controlled trial enrolled children aged 8-18 years with IBS or FAP-NOS, diagnosed using the Rome IV criteria. Participants were assigned to a 4-week low-FODMAP diet or a regular diet. The primary outcome was the proportion of responders, defined as those with a ≥30% reduction in abdominal pain, corresponding to at least the Reliable Change Index (≥25 mm change on visual analog scale), over the 4-week intervention. Results: The trial was terminated early due to recruitment challenges. Of the 74 originally planned participants, 42 (57%) were randomized, and 38 (51%) received the intervention, with 19 in each group. In the available case analysis (including only participants with outcome data at week 4), there was no difference in the proportion of responders between the low-FODMAP (7/13) and regular diet (5/13) groups at week 4 [relative risk 1.4 mm, 95% confidence interval (CI), 0.6-3.3]. In the secondary outcomes, only a greater mean reduction in abdominal pain intensity was observed in the low-FODMAP diet group at week 4 (mean difference = -20.8 mm, 95% CI, -40.0 to -1.6; 26/38). Adverse events were rare in both groups ( Conclusions: This early-terminated RCT did not demonstrate a significant benefit of the low-FODMAP diet in increasing the proportion of responders among children with IBS and FAP-NOS. However, due to early termination and missing data, the findings should be interpreted with caution. Nonetheless, the study provides insights into challenges in conducting controlled dietary intervention trials in children (e.g., the demanding nature of a highly restricted dietary protocol and practical issues related to school settings and caregiver involvement), which may inform the design of future studies. Clinical Trial Registration: https://www.ClinicalTrials.gov Identifier: NCT04528914.