Chemical composition of refluxate

The reflux of gastric contents into the aerodigestive tract has been linked to a variety of oesophageal, oral, airways and respiratory diseases. The composition of refluxate is not merely secreted gastric juice and instead represents a complex mixture of gastrointestinal secretions and exogenous factors. Within the stomach, gastric juice mixes with proximal (saliva) and distal (pancreatic juice, bile) gastrointestinal secretions. New microbes enter the stomach via ingested food, saliva and other aerodigestive secretions and join the gastric microbial community. Ingestion of food may itself drive a number of physiological actions that are linked to the occurrence of reflux. Digestive enzymes, acid and bile may cause direct damage to the unprotected mucosal tissues of the aerodigestive tract. Further from this, the processes of digestion within the stomach may release new antigen that have the potential to cause an immunological response. The gastric microbiome is largely similar to that of the aerodigestive tract, so its role in damage as a result of reflux is unclear. The complex interplay between all of the above factors is not currently well understood, although is likely to play a role both in the damaging potential of refluxate as well as the frequency and volume of reflux events.