Belching

Did You Know?

• In microgravity environments, burping is frequently associated with regurgitation, known as wet burping.
• The previous Guinness World Record for loudest burp was held by Paul Hunn for 12 years.
• Retrograde cricopharyngeus dysfunction (R-CPD) was first discovered in 1987.

Causes

The body uses the belch reflex to release swallowed air that cannot be absorbed in the gut. This air moves from the stomach into the esophagus after the lower esophageal sphincter relaxes. The resulting stretch in the esophagus triggers the reflex, which opens the upper esophageal sphincter and lets the gas escape into the pharynx. The gas is mostly oxygen and nitrogen from the atmosphere, though carbonated drinks and beer add carbon dioxide. Habits like chewing gum, sucking hard candy, talking while eating or drinking, and smoking increase air swallowing, and some people swallow air nervously. Belching can also indicate indigestion-related conditions such as hiatal hernia, gastritis, GERD, ulcers, H. pylori infection, gallbladder disease, or food allergies.

Clinical significance

Belching that happens too often can be traced to one of two specific disorders, both classified as gastroduodenal issues and also known as disorders of gut–brain interaction. The first, supragastric belching, takes place in the esophagus above the stomach and is considered voluntary. Because the reflux in this case is mostly non-acidic, drugs that lower stomach acid, like proton pump inhibitors, do not help. This type is frequently tied to anxiety and is seen as a behavioral disorder, similar to rumination syndrome. The second, gastric belching, starts in the stomach and is involuntary. Gas builds up in the cardia, the area nearest the lower esophageal sphincter, which triggers stretch receptors in the stomach wall. This sets off a vagovagal reflex that briefly relaxes the sphincter, a process called transient LES relaxation, letting air escape into the esophagus. Either type of belching disorder can bring on reflux. On the other end of the spectrum, a condition called retrograde cricopharyngeus dysfunction, or retrograde upper esophageal sphincter dysfunction, prevents belching entirely because the cricopharyngeus muscle cannot relax. Symptoms often include stomach rumbling, bloating, and flatulence, with less common issues like painful hiccups, nausea, constipation, excess saliva, or shortness of breath. An ENT doctor can diagnose it using high-resolution manometry, esophageal manometry, or fluoroscopy. A single botox injection successfully treats about 80% of patients; if that fails, a partial cricopharyngeal myotomy is an option. Rarely, chest pain can occur with burping.

Society and culture

Some South Asian cultures view burping as acceptable in particular situations, such as a guest burping to show the host that the meal was satisfying. In Japan, burping during a meal is considered bad manners, and it is also considered unacceptable in Western cultures like North America and Europe. Babies accumulate gas while feeding and may experience discomfort until burped; burping an infant involves placing the child against the adult's shoulder and lightly patting the lower back. A burp cloth or burp pad is sometimes used to protect clothing from vomiting. The Guinness World Record for the loudest burp was 112.4 dB, set by Neville Sharp from Darwin, Australia in 2021, approximately as loud as a jet engine at 100 m. Voluntary burping can be induced by swallowing air and expelling it, and manipulation of the vocal tract can produce burped speech, which may serve as an alternative means of vocalisation for people who have undergone a laryngectomy, known as esophageal speech.

Other animals

Cows, dogs, sheep, and many other mammals burp. In ruminants like cows, most burped gas is a digestive byproduct, including methane made only by methanogenic archaea; E. coli and other bacteria cannot produce methane. Ninety-five percent of this gas leaves as burps. A lactating cow releases about 322 grams of methane daily, over 117 kilograms yearly, making commercial cattle a major source of human-caused methane emissions and a contributor to the greenhouse effect. To cut this, Australian scientists developed an anti-methanogen vaccine. Cows burp heavily partly because they are fed foods like corn and soy that are hard to digest; switching to alfalfa and flaxseed, closer to their wild diet, reduces burping. Birds have no documented burps, though ornithologists see no physical barrier; however, bird microbiota lack the gas-producing bacteria mammals use for digestion, so gas rarely builds up.