Introduction Excessive belching is commonly reported in patients with gastroesophageal reflux disease (GERD). The main determinant of troublesome belching in reflux patients is thought to be supragastric belching (SGB). We looked at the prevalence of SGB and small intestinal bacterial overgrowth (SIBO) in GERD patients with excessive belching.

Methods Using retrospective data, we identified 41 adult patients referred to a speciality reflux centre with excessive belching, and who carried out a 24-hour esophageal pH-impedance test and lactulose breath test (LBT). Pathological SGB was defined as >13 per 24 hours and SIBO was determined by a rise in hydrogen ≥20 ppm from baseline within 90 minutes, respectively. These data were analysed statistically using McNemar’s test, Fisher’s exact test and independent t-tests.

Results All patients reported excessive belching and at least one other typical symptom of GERD (85% reported heartburn and 63% reported regurgitation). SIBO was more prevalent (46.3%; 95% CI, 30.7–62.6%) than SGB (17.1%; 95% CI, 7.2–32.1%; P = 0.012). SGB was not associated with a positive reflux-symptom association for heartburn or regurgitation (P > 0.05), but the presence of SIBO was associated with a positive reflux-symptom association for regurgitation (P = 0.004). Patients with a positive reflux-symptom association for regurgitation had significantly more hydrogen production on LBT than those without (mean AUC 275.8 ppm vs 139.1 ppm; P = 0.028).

Conclusions A larger proportion of reflux patients with excessive belching have SIBO compared to SGB. Therefore, SIBO may be the primary cause of belching in GERD. In addition, SIBO was associated with a positive reflux-symptom association for regurgitation and hydrogen production on LBT was significantly greater in these patients. It may be that excessive bacterial fermentation in the proximal gut contributes to reflux symptoms, but further studies are required to look at the relationship between SIBO and GERD.