Gastric belching is the escape of swallowed intragastric air that enters the esophagus during a transient lower-esophageal sphincter relaxation (TLESR) – the lower-esophageal sphincter is a ring-like muscle structure that is found at the end of the esophagus (the swallowing tube) and which contracts to prevent food from migrating upwards from the stomach into the esophagus. Episodes of TLESRs allow relief of the stomach from any excess amount of air, thereby preventing bloating by minimizing the passage of large volumes of gas into the intestines. Gastric belches occur 25 to 30 times per day and are physiological; they are essentially involuntary and are
controlled entirely by reflexes.
It remain poorly understood what causes supragastric belching and what triggers patients to start this behavior. Some patients report that initially they belched purposefully to relieve a sensation of bloating or abdominal discomfort but that with time they lost control of the belching.