PHILADELPHIA — , according to a new study.
The low FODMAP diet is the most evidence-based dietary therapy for patients with IBS, but we know that “only about 50% of our patients respond to it,” said principal investigator Prashant Singh, MD, assistant professor at the University of Michigan in Ann Arbor, Michigan. “Exhaled breath gases represent bacterial fermentation of dietary carbohydrates. These measurements could provide a simple biomarker for response to low FODMAP diets.”
Even before starting the low FODMAP diet, “you could see notable differences in breath test patterns between responders and nonresponders,” he said. “We saw that low FODMAP responders had higher hydrogen (H2) and lower methane (CH4) at baseline than nonresponders and had a greater drop in hydrogen following FODMAP restriction vs nonresponders.”
He added that these results imply that responders to this diet may exhibit differences in baseline microbiota composition regarding saccharolytic capacity and/or methanogens.
Singh presented the findings at the American College of Gastroenterology (ACG) 2024 Annual Scientific Meeting.
Breaths That Can Predict Response
To determine if pre-intervention non-fasting breath patterns are associated with a clinical response to low FODMAP diets, Singh and colleagues enrolled 284 self-selected participants (mean age, 45.2 years) with mild to moderate gastrointestinal (GI) symptoms. Participants used an app-connected breath analyzer to record hourly, non-fasting H2 and CH4 levels during waking hours, in addition to logging meal content and symptom severity (bloating, abdominal pain, and flatulence) on a 0-10 scale.
Patients were directed to consume their habitual diet for 1 week, before following an app-directed low FODMAP diet for 1 week. Responders were defined as those with a ≥ 30% reduction in at least one mean symptom score. The researchers then compared average hourly H2 and CH4 levels and symptom scores at baseline between low FODMAP diet responders and nonresponders.
Of the participants, 111 were classified as responders and 173 as nonresponders. There were no significant differences between the groups in gender, age, body mass index, or FODMAP per calorie.
Following FODMAP restriction, responders had consistently lower abdominal pain throughout the day and lower bloating and flatulence predominantly in the latter part of the day. Nonresponders experienced no significant changes in key abdominal symptoms after adopting the low FODMAP diet.
The researchers found that breath tests taken at baseline revealed predictive trends between the groups, even though average FODMAP consumption did not significantly differ between them. Baseline H2 levels were higher among responders than among nonresponders, especially in the morning and evening. However, responders had lower baseline CH4 levels throughout the day.
Following FODMAP restrictions, responders had a significant drop in non-fasting H2 but not CH4, whereas nonresponders did not have a significant drop in either.
The study was limited by the fact that participants were not clinically diagnosed with IBS, their GI symptoms were mild overall, and no data were available on stool consistency/frequency or fecal microbiome composition for correlation with exhaled breath gas levels.
