Breath methane in functional constipation: response to treatment with Ispaghula husk

Background Colonic fermentation produces hydrogen (H 2 ), and also produces methane ( CH 4 ) in subjects with methanogenic flora (M+). Methane production has been associated with chronic constipation ( CC ) and with changes in gut motility. To determine CH 4 production in CC compared to controls, and to assess whether the therapeutic response to Ispaghula husk in CC differs between CH 4 ‐producers and non‐producers. Methods Forty‐eight patients with functional constipation or irritable bowel syndrome‐constipation and 19 healthy age‐and‐sex‐matched volunteers ( HV ) filled in a 1‐week symptom diary and a dietary questionnaire. They then underwent a lactulose breath test ( LBT ) to measure H 2 and CH 4 production (peak and area under the time‐concentration curve, AUC ‐) and a colonic transit time ( CTT ) assessment. In patients, measurements were repeated after a 4‐week treatment with Ispaghula husk. Key Results Prevalence of M+ in patients was 60.5% vs 52.6% in HV ( p  = 0.37). Patients had significantly longer CTT and greater production of both H 2 and CH 4 during LBT . There was a significant correlation between CH 4 production and CTT ( r  = 0.51; p  = 0.07). Treatment response rate was similar for M+ and M− patients (58.3% vs 52.9%; p  = 0.76) as were the increases in bowel movements and Bristol score, changes in abdominal discomfort and bloating. In M+, treatment reduced CTT (−10 ± 35 h; p  = 0.029 vs baseline) and CH 4 levels: peak CH 4 (−13 ± 24 ppm; p  = 0.014) and CH 4 ‐ AUC (−817 ± 3100 ppm/min; p  = 0.04). Conclusions & Inferences Although CH 4 production has been associated with CC pathophysiology, we found that CH 4 status did not negatively affect the response to Ispaghula husk treatment. The measurement of CH 4 levels as a biomarker tool for CC requires further appraisal.