Production of certain gases and their relative concentrations affect gut function, may have pathogenic roles in several gastrointestinal (GI) disorders, and can, therefore, be useful as biomarkers for specific diseases.1 Under normal gut conditions, the most prevalent gases include CH4, CO2, H2, H2S, and NO.1,2 One of the major difficulties in understanding their physiology and functional capacity is the lack of direct access, because sampling through insertion of tubes into mouth or anus is inconvenient and invasive.