Apart from acid, digestive enzymes are produced by the stomach to assist the breakdown of the received food.

The role of these enzymes, Pepsin, Chymotryspisn and Trypsin is to break down the proteins into peptides and amino acids for easy absorption in the intestines.

The Peptest devised by Professor Dettmar, tests the saliva for pepsin. Since this enzyme is not meant to exist outside the stomach, if found in the saliva, it proves the presence of extra-oesophageal reflux.

It is an easy test and can even be done by purchasing a test kit for home use.

It has been used to detect extra-oesophageal reflux in children with "glue ear" (otitis media). A paper published in May 2015, "Diagnosis of extraesophageal reflux in children with chronic otitis media with effusion" using Peptest, published in the International Journal of Pediatric Otorhinolaryngology [t-iii] found "Pepsin was detected in 1/3 of middle ear specimens of patients with OME. These patients probably suffer from more severe reflux and therefore would be potential candidates for antireflux therapy. However, this has to be confirmed in further studies."