Incidence of Predominant Methanogenic Flora in Irritable Bowel Syndrome Patients and Apparently Healthy Controls from North India

Background Flatulence is a common symptom in patients with irritable bowel syndrome (IBS). This may be due to production of hydrogen by intestinal flora. With the presence of methanogenic flora, 4 mol of hydrogen (H₂) are used with 1 mol of carbon dioxide (CO₂) to produce 1 mol of methane (CH₄), a process greatly reducing the volume of gas in the colon. However, the prevalence of methanogenic flora has not yet been reported in healthy and IBS patients from North India. Therefore, this study was planned. Methods This study was conducted prospectively and included 345 patients with irritable bowel syndrome (fulfilling Rome II criteria) and 254 age- and gender-matched apparently healthy controls. Each subject underwent a hydrogen breath test using 10 g lactulose after an overnight fast. An SC Microlyser from Quintron, USA, was used to measure methane and hydrogen at baseline and at every 30 min for 4 h. Subjects with fasting methane concentration <10 p.p.m. were labeled as low methane producers (LMPs) and > 10 p.p.m. as predominant methane producers (PMPs). Results The IBS and control groups included 66.78% and 67.53% men, respectively. Mean age in the two groups was 48.52 ± 30.54 years (range 15–68 years) and 45.67 ± 30.54 years (range 15–78 years), respectively. Prevalence of predominant methanogenic flora in IBS and control groups was 14.5% (50/345) and 34.6% (88/254), respectively (P < 0.001). Fifty-two out of 254 (20.6 %) were PMPs and 36 out of 254 (14.0%) were LMPs in controls. In contrast to this, IBS patients had 17 out of 354 (4.9%) that were PMPs and 33 out of 345 (9.6%) that were LMPs. Conclusion Methanogenic flora was significantly lower in IBS patients from North India than in apparently healthy subjects. This may be one of the causes of flatulence in IBS patients.