The cephalic phase of gastric acid secretion has been a topic of great interest to physiologists and physicians since its description by Pavlov 100 years ago.1 In classic “sham” feeding studies performed on dogs equipped with an oesophageal stoma and a gastric fistula, Pavlov demonstrated that food was a prompt and powerful stimulant of gastric secretion. This stimulation occurred despite the fact that the ingested food entered the dog's mouth and pharynx and exited through the stoma, never actually reaching the stomach. Pavlov went on to demonstrate that severing the vagus nerves just above the diaphragm abolished the gastric acid secretory response to sham feeding in dogs. His experiments demonstrated that sham feeding elicited a potent gastric acid secretory response via the vagus nerves.

Although experiments involving surgically created fistulas could not be conducted in humans, in the 1970s Knutson and Olbe developed a “modified” sham feeding technique to study the cephalic phase of gastric acid secretion in patients with duodenal ulcer disease.2-4 Patients chewed and expectorated appetising food without swallowing it, and a tube inserted into the stomach collected gastric fluid for acid analysis. Using modified sham feeding in …