Previous studies have shown a reduction of gastrointestinal symptoms in irritable bowel syndrome (IBS) patients following a low FODMAP diet (LFD). It remains unknown, which disorders of gut-brain interaction (DGBI) patients, would benefit most from LFD. We aimed to analyze LFD response regarding a preceding nutrient challenge test (NCT).
Data of 110 consecutive DGBI patients undergoing NCT and LFD between 08/2015-2018 were analyzed retrospectively. LFD response was assessed by changes in IBS – Symptom Severity Score (IBS-SSS). In mixed-effects linear regression models the impact of hydrogen values and abdominal symptoms during NCT, performed with 30g lactulose and 400ml liquid test meal, on IBS-SSS changes were analyzed.
LFD induced a significant IBS-SSS reduction of 78 points (95% CI: 50-96; p < 0.001). Patients with higher NCT-induced hydrogen increase during proximal intestinal transit had a significantly better LFD response (-66 IBS-SSS reduction per 10 ppm hydrogen increase, 95% CI -129 – -4, p = 0.045). Additionally, the higher the NCT-induced maximum hydrogen increase during mid- and distal intestinal transit the better the responses to LFD (-6 IBS-SSS per 10ppm maximum delta hydrogen, 95% CI -11 – -1, p=0.040). There was no association of LFD response with abdominal symptom generation during NCT.
Our study is the first one analyzing and demonstrating significant associations between NCT results and LFD response. These findings are of high clinical importance, as they identify a subgroup of DGBI patients that may profit most from a restrictive LFD as first-line therapy.

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