Dr John P Wright
Updated: 22 May 2007
Belching is an eructation of air which may vary from the gentle gurgle of the neonate to the attention drawing explosion associated with members of the Balmy Army.
In some cultures it may be acceptable after a meal but in others it separates the “A” list from the “B”s of the social whirl.
So why do we sometimes belch? At the simplest level we are releasing excessive air that has accumulated in the stomach. The rate of accumulation depends on the rate of air swallowing versus the accommodating relaxation of the stomach to accommodate the air.
Every time we swallow a little air travels with the bolus. When relaxed 20% of the swallowed air which is oxygen, will be rapidly absorbed and utilized. The remaining 80% which is nitrogen, may be absorbed or quietly belched out. Under stress however all of this changes and quite large volumes of swallowed air with or without liquid gastric contents may rise up requiring urgent swallowing to avoid embarrassment. This is often seen when politicians speak and is passed off as a moment of contemplative thought rather than the stressed mental gymnastics required to keep the required honest concerned facial expression.
The physiological process is that the swallowed air dilates the proximal stomach which activates the stretch sensors in the gastric wall which in turn initiate a vagovagal reflex. This relaxes the lower oesophageal sphincter and allows the higher gastric pressure to push the air up into the oesophagus where it may induce secondary contractions which push the air back into the stomach or allow further relaxation of the upper oesophageal sphincter and belching.
In the medical context belching is frequently one of the symptoms associated with acid reflux. In these patients other reflux symptoms such as heartburn and regurgitation dominate the belching. Acid inhibition will normally relieve these symptoms although a higher dose than normal is sometimes required. . In addition to gastric content reflux it might be that the movement of air up the oesophagus may in itself provoke feelings of heartburn and chest pain,
In patients whose dominate symptom is belching, the situation is less simple. In a recent study it was found that contrary to popular belief there is no relationship between frequent belching and acid reflux, air swallowing and the amount of air in the stomach. This aerophagia is a repetitive action of air swallowing and belching unassociated with heartburn. Patients may belch up to 20 times a minute. It is usually associated with an anxiety disorder and most patients will recognize the role that anxiety plays in their affliction. A common belief however is that there must be some fermentation taking place to account for all the air passed. Studies have shown no difference in the gas formation or storage in the stomach in this setting. What has been shown is that these chronic belchers move large volumes of air down into the upper oesophagus then promptly belch it up again. This is called supragastric belching. It is achieved by inspiring with a closed glottis thus dragging air into the thoracic cage via the oesophagus and via a contraction of the tongue, palate and pharyngeal muscles to inject air into the upper oesophagus. This is the process whereby laryngectomized patients learn to “speak” again. It appears therefore that these grossly belching patients have a behavioral disturbance.
The treatment of physiological belching involves the reduction of swallowed air and the relaxation of the upper stomach. Lifestyle factors and stress levels need to be addressed but there is no specific medical treatment to achieve these objectives. A reduction in gastric acid with proton pump inhibitors may well help but larger than normal doses may be required.
To answer the question as to whether belching is a blessing or a curse we need to look at those who can not belch. Typically this is the patient who has had a fundoplication as a surgical anti-reflux measure. These patients often woe the day that they gave up the physiological pleasure of a good belch in favour of not having to taking acid inihibitory medication. This is particularly the case when they find themselves back on medication within a year but now with excessive intestinal air and bloating. To trade the blessing of a good belch for excessive flatus may be a mistake if not a curse’