S739 Breath Test Responses to Key FODMAP Substrates in a Symptomatic Cohort

Introduction: A low FODMAP-diet (LFD) is an effective strategy for managing symptoms in patients with irritable bowel syndrome (IBS). However, the initial restriction phase can be challenging. Standardized carbohydrate intolerance breath tests might be useful in predicting more personalized LFD restriction. This study aims to evaluate the breath test responses to following substrates: fructose (F), inulin (I), lactose (L), and sorbitol (S). Methods: Seven hundred thirty-four self-selected participants (48 ± 13 years, 56% women, 24.3 ± 4 kg/m2 body mass index) performed breath tests at home in a fasted state using a personal app-connected breath analyzer (AIRE; FoodMarble, Ireland). After recording a baseline breath reading, they ingested a substrate (fructose 25 g, inulin 10 g, lactose 25 g or sorbitol 10 g) and recorded breath readings every 15 min for 3 hours (every 30 min for inulin). H2 positivity (a rise of ≥20 ppm above baseline), and CH4 positivity (a rise of ≥10 ppm above baseline) are pooled for this analysis. Participants completed all 4 FODMAP tests and reported their most bothersome symptoms prior to testing. Results: The average number of positive tests was 1.79 per participant, with 9% (65) positive in all 4 tests and 17% (126) negative in all 4 tests. The most common co-occurrences of positivity were S+I+F (11%), S+I+F+L (all) (9%), S+F (8%), S+I (7%), with 14% intolerant to sorbitol only. Where only a single FODMAP was implicated, the fructose-only group (3%) reported the highest frequency of abdominal pain, belching, nausea and heartburn at baseline, whereas the inulin- and sorbitol-only groups (4%, 14%) reported similar symptom frequency at baseline, with flatulence, fatigue and constipation being most notable for these 2 groups. The lactose-only group (4%) reported lower heartburn than the other groups. Conclusion: The majority of participants were breath-test positive for an average of 2 FODMAP groups, with sorbitol being the substrate they were most commonly positive for. Fructose positivity is more associated with upper-GI symptoms, possibly due to higher osmotic load in the proximal small intestine. Conversely, inulin and sorbitol-related symptom profiles may be more indicative of colonic fermentation and higher overall gas production. More research is needed to better understand the role of baseline symptom profiles and breath test responses in the personalization of FODMAP restriction.