Methanogenic Flora does not Influence Therapeutic Responses to Fiber during Chronic Constipation: A Randomized Crossover Clinical Trial

Abstract

Introduction: Methane gas production by gut microbiota has been associated with Chronic Constipation (CC) and delayed intestinal transit. Therapeutic fibre is a substrate for this fermentation and its effects are influenced by gas production. Our trial focuses on the possible deleterious effect of methane production in CC patients treated with fermentable fibre. Methods: A cross-over, double blind, randomized trial comparing two types of fibre, with different fermentability, partially (Isphagula husk) or poor (methylcellulose). Before and at the end of each 4-week treatment phase we evaluated stool characteristics, colonic transit time and hydrogen/methane production. Results: Seventy-six patients with CC were evaluable (93% women); mean age was 50.1 years; 19.8% had IBS-C/80.2% functional constipation (Rome III criteria) and 69.7% were methanogenic (M+). Therapeutic response to fibre was similar with Ispaghula and methylcellulose (25.0% vs. 22.4% p=0.62) regardless of methanogenic status. Colonic transit shortened significantly only with Isphagula (Beta=-17.2 h). In M+ group, methylcellulose reduced methane levels (p=0.004) and Isphagula had no effect. Both fibres produced no changes in abdominal pain (p=0.76) and distention (p=0.11). Conclusions: In chronic constipation neither methanogen status nor fermentative characteristics of fibre influences therapeutic response. Changes in colonic transit may explain different fibre effects in gas production. This randomized trial confirms the results of our previous, not controlled study, which ruled out a deleterious effect of methanogenic status using Ispaghula husk in chronic constipation. Therefore, his easy-to-get biological marker (methanogenic status) is not useful in this context.