A POSSIBLE ROLE FOR BILE-ACID IN THE CONTROL OF METHANOGENESIS AND THE ACCUMULATION OF HYDROGEN GAS IN THE HUMAN COLON

This study investigated a possible role for primary bile acid in the c ontrol of methanogenesis in the human colon. Production of hydrogen an d methane was measured in anaerobic faecal cultures derived from faece s of six 'non-methanogenic' and three methanogenic healthy humans. Usi ng a sensitive technique for gas measurement, methane was detected in all faecal cultures, including those from 'non-methanogenic' humans. B ile acid inhibited methanogenesis in a dose-response fashion in the in vitro 'non-methanogenic' and methanogenic faecal cultures. Inhibition was significant at bile acid concentrations > 0.05%. Methanogenesis c orrelated with methanogen (methanogenic bacteria) numbers. If this inh ibition occurs in vivo, then it would explain much of the epidemiology of non-methanogenesis in humans. From an analysis of net hydrogen pro duction by the faecal cultures, it is inferred that bile acid inhibits other hydrogen-consuming bacteria in addition to methanogens. These i n vitro data suggest a major role for bile acid in the accumulation of hydrogen gas in the colon. Possible links between bile acid induced a ccumulation of gas and irritable bowel syndrome are discussed.