Methane excretion in man--a study of breath, flatus, and faeces.

In this paper aspects of the variability of methane producing status have been examined, and a survey of breath methane excretion in various clinical and control populations is reported. Prevalences of methane excretion were 54% in healthy controls, 53% in non-gastrointestinal patients and 32% in gastrointestinal patients. Patients with Crohn's disease, ulcerative colitis, and pneumatosis cystoides intestinalis had significantly lower prevalences of methane excretion (13%, 15%, and 11% respectively). Faecal constituents and in vitro incubation analysis were similar in breath methane excretors and non-excretors. Several patients did not excrete methane in the breath although methane was present in colonic gas. The results indicate that different gastrointestinal patient groups have different prevalences of breath methane excretion and that all healthy subjects may produce methane but only when the production reaches a threshold does it appear in the breath.