Reassessment of the role of methane production between irritable bowel syndrome and functional constipation

Abstract

Background and aims: Modifications of intestinal gas due to changes in microbiota may produce different symptoms. Our aim was to assess whether different patterns of hydrogen (H₂) and methane (CH₄) excretion were related to some intestinal disturbances.

Methods: Six hundred and twenty-nine consecutive patients underwent a 50 g-glucose breath test (GBT) on account of intestinal symptoms, which were evaluated by means of a questionnaire. "H₂-producers" and "CH₄-producers" were defined as with the presence of H₂ peak >12 ppm more than the basal sample and mean CH₄ excretion of 2 ppm, respectively. Forty healthy subjects were studied as controls.

Results: A small intestinal bacterial overgrowth was found in 45 cases (7.2%) and was associated with older age (p=0.0122). Methane production occurred in 32.3% of the study population. Methane excretion was strictly related to chronic constipation (p<0.001). Median CH₄ excretion was higher in constipated patients compared with patients with normal daily stools (p=0.0406) and even more with patients complaining of diarrhea (p=0.0011). Different criteria for defining "methane-producers" provided similar results. Mean methane excretion of "methane producers" was 30.3 ppm in functional constipation and 21.5 ppm in constipation-irritable bowel syndrome (C-IBS) (p=0.0458).

Conclusions: Methane excretion is clearly associated with alterations in intestinal motility, particularly favouring those with constipation. Mean methane excretion was higher in subjects suffering from functional constipation than C-IBS. Mean methane excretion ≥ 2 ppm appears to be an appropriate term to define "methane-producers".