Effect of MethylceIlulose or Psyllium on Fermentation of Inulin Assessed Using a Gas Sensing Capsule

The investigators plan to measure the local (in vivo) production of hydrogen when methylcellulose is ingested, to see if the investigators can show a shift of the site of fermentation to the distal colon. The investigators will achieve this using the Atmo pill, a recently developed ingestible gas-sensing wireless capsule manufactured by Atmo Biosciences. The pill is very similar in appearance and dimensions (26·8 mm long by 11·7 mm in diameter) to the Smart Pill, an FDA approved wireless capsule which measures local pH, which has been widely and safely used for over a decade. The Smart Pill is recommended for transit measurement by the American ACG Clinical Guidelines on Gastroparesis 3. The Atmo pill differs from the Smart Pill in measuring hydrogen and carbon dioxide within the colonic lumen rather than pH. The pill emits a radio signal to a small device worn by the participant to record the measurements periodically 4.