LAUSR

We have read with interest several recent papers in Gut that have reported novel insights about the potential consequences of reduced gastric acid secretion. These include reports that proton pump inhibitor (PPI) use increases the risks of developing diverse diseases including gastric adenocarcinoma 2 and severe COVID19 infection. An intriguing recent paper has also shown that pathological suppression of gastric acid secretion in people with autoimmune atrophic gastritis does not predispose to gastric adenocarcinoma development unless they are also infected with Helicobacter pylori. These patients are, however, more prone to developing type 1 gastric neuroendocrine (carcinoid) tumours (NETs). Interestingly, gastric NETs do not develop in people who have H. pylori induced atrophic gastritis or following long term druginduced acid inhibition. These observations highlight the complexity of the regulation of gastric acid secretion and suggest that the underlying cause of hypochlorhydria is a major determinant of its consequences. We have previously reported that different conditions that reduce gastric acid secretion have different consequences on the gastric microbiome and this may be one contributory mechanism. The extent and type of the hypergastrinaemia that is associated with hypochlorhydric conditions also varies considerably and may play a role. None of these recent advances in gastroenterology would have been possible without the seminal discovery of the presence of hydrochloric acid in gastric juice by William Prout FRS in 1823. As the current secretary (RL) and treasurer (DMP) of the ‘Prout club’, we thought it was important to acknowledge and remember the 200year anniversary of this important event. The Prout club was formed by the late Dr Hugh Baron (Consultant Gastroenterologist at St Mary’s Hospital, London) in 1972 to commemorate Prout’s discovery. The club meets annually during the British Society of Gastroenterology conference for dinner and a debate on a topic relevant to gastric acid secretion. Coincidentally, our 2022 meeting in Birmingham marked the 50th anniversary of the Prout club’s formation. Prout (1785–1850) completed his MD at the University of Edinburgh in 1811 and made several important contributions to science and medicine. In addition to his discoveries about the composition of gastric juice, he is probably best known within the field of chemistry for ‘Prout’s hypothesis’ concerning the structure of the atom. The legacies of his discoveries have been enormous. Our modern capacity to potently inhibit gastric acid secretion first with H2 receptor antagonists, subsequently with PPIs and most recently with potassiumcompetitive acid blockers has revolutionised the treatment of peptic ulcers and gastrooesophageal reflux disease over the 50 years since the Prout club was founded. These drugs, along with a recognition of the importance of H. pylori infection, have meant that surgery for benign diseases of the upper gastrointestinal tract is largely an extinct discipline. Such a statement would have been unimaginable to a general surgeon practising before the launch of cimetidine in 1976. However, it is important to remember that the normal physiological state of the human stomach is to produce concentrated hydrochloric acid. Although altering normal gastric acid secretion can be useful to treat certain diseases, it is not surprising that disturbing the physiological state, either as a result of pathology or pharmacology, may have unintended consequences. We are sure that Gut will publish many more important papers in this field before the Prout club celebrates its centenary in another 50 years’ time and we speculate that many of these will involve studies of the microbiome. There is still much to learn about gastric acid and its role in the pathogenesis of various human diseases. The legacy of Prout’s important discovery lives on.