All FODMAPs Aren't Created Equal: Results of a Randomized Reintroduction Trial in Patients With Irritable Bowel Syndrome.

BACKGROUND & AIMS: A diet low in fermentable oligo, di, monosaccharides, and polyols (FODMAPs) is one of the recommended management strategies for irritable bowel syndrome (IBS). However, while effective, adherence to restricting dietary FODMAPs can be challenging and burdensome. The question remains whether limiting all FODMAPs during the restrictive phase of the diet is necessary for symptomatic improvement in the dietary treatment of IBS, or if targeting selected groups of FODMAPs for restriction is sufficient for clinical response. Our study aimed to determine which individual FODMAPs are most likely to lead to symptom generation in patients with IBS who have improved with fodmap restriction. METHODS: Patients meeting Rome IV criteria for IBS were invited to participate in a 12-week study to identify individual FODMAP sensitivities. Those subjects who demonstrated symptom improvement after a 2- to 4-week open-label FODMAP elimination period were recruited to a 10-week blinded-phased FODMAP reintroduction phase of 7 days for each FODMAP. Throughout the study period, daily symptom severity (0-10 point numerical rating system) was recorded. A mixed effect statistical analysis model was used. RESULTS: Between 2018 and 2020, 45 subjects were enrolled. Twenty-five subjects improved with FODMAP elimination, and 21 patients continued into the reintroduction phase of the study. Fructans and galacto-oligosaccharides (GOS) both were associated with worsened abdominal pain (P = .007 and P = .04, respectively). GOS were associated with an increase in bloating (P = 03). Both bloating and abdominal pain worsened throughout the study, regardless of the FODMAP reintroduction (P = .006). CONCLUSION: Our results suggest that the reintroduction of select FODMAPs may be responsible for symptom generation in patients with IBS who have responded to a low FODMAP diet, and provide a strong rationale for performing a future trial comparing the treatment effects of a limited low-FODMAP diet and a standard low-FODMAP diet. CLINICALTRIALS: GOV: NCT03052439.