Everyone belches or burps at one time or another to relieve gas buildup in the stomach.
It may often be embarrassing, but for the vast majority of people, occasional belching is not a problem that needs medical attention.
Belching (eructation) is triggered in two ways. First, too much gas is produced in the stomach by eating such foods as bran, raw fruit, vegetables, or by drinking gaseous liquids such as beer, soda, or seltzer. Even apple, grape, and prune juice can lead to belching.
The second cause is swallowing too much air, a condition known as aerophagia in chronic cases. Strange as it may seem, it does not take much effort to swallow air. Gulping one's food, drinking too fast, or talking while eating brings in excessive amounts of air, which can build up in the gastrointestinal tract. Chewing gum, sucking on candy, smoking a pipe or cigarettes, or chewing on a cigar also greatly increase air intake and, with it, belching. Aerophagia occurs normally in small amounts while eating and drinking, but some people unconsciously swallow repeated boluses of air at other times, especially when anxious.
Most swallowed air is subsequently eructated (belched); only a small amount passes into the small bowel, the quantity apparently being influenced by posture. The esophagus empties into the posterior aspect of the stomach. When the person is upright, air rises above the liquid contents of the stomach, comes into contact with the gastroesophageal junction, and is readily belched. When the person is supine (lying on his or her back), air trapped below the fluid tends to be propelled into the duodenum (part of the small intestine).
Excessive salivation may also lead to increased air swallowing and may be associated with various digestive disorders (e.g. peptic ulcer), ill-fitting dentures, or with nausea of any etiology. Belching may be associated with the use of antacids such as baking soda. Attributing the relief of ulcer symptoms to belching rather than antacids, the person continues to belch to relieve distress.