Background: Detection of the gas methane (CH4) in exhaled breath is positively correlated to constipation, according to some research. Intestinal CH4 can slow intestinal transit time, and directly inhibit gut motility. Whether these alterations are a cause or a consequence of constipation is unknown.

This is an open trial, investigating the effect of L. reuteri Protectis DSM 17938 on the frequency of bowel movements and the level of methane in exhaled breath. The subjects were 20 constipated adults, all presenting with methane in their breath. Lactulose breath test was used at baseline and after 4 weeks of consumption of L. reuteri Protectis (2 tablets per day)

Positive detection of CH4 was defined as: production of > 5 ppm of CH4 at any time during four hours after oral ingestion of a 200-ml solution with 10 g of lactulose (= lactulose breath test).

Conclusion: Methane production in constipated adults can be reduced by daily ingestion of L. reuteri Protectis for four weeks. Reduced production of methane was associated with normalized number of weekly bowel movements. Ingestion of L. reuteri Protectis seems to modify the composition or the metabolism of methane producers of the gut microbiota.