The Truth About Gas…More Normal Than You Think?


Gastrointestinal gas is part of the human condition. The extent of which that person becomes aware of it dictates if gas is a problem or not.


Belching is the audible escape of air from the esophagus into the upper airway. Almost all air that is belched is a consequence of air swallowing.

Belches that arise from the stomach are called gastric belches and are caused by relaxations of the lower esophageal sphincter to allow swallowed air to escape from a distended stomach. This allows for automatic decompression of the stomach and may occur up to 25-30 times a day.

Supragastric belches are due to air swallowing and immediate expulsion of the air before it can reach the stomach. Some patients may voluntarily belch to relieve an uncomfortable abdominal sensation.


It is normal to pass gas between 14-25 times a day! 99 percent of the gas we pass is made up of nitrogen, oxygen, hydrogen, carbon dioxide and methane.

The four former gases are also a large component of the air we breathe. Trace gases containing sulfur (also found in rotten eggs) contribute to the odor that is experienced. A perception of excessive gas may be associated with carbohydrate malabsorption such as see in lactose intolerance.

Other culprits are sugar alcohols such as sorbitol and xylitol that are used as artificial sweeteners.


This may be associated with excessive belching due to air swallowing or carbohydrate malabsorption associated with flatulence. Most often it is a perception of increased intestinal air as studies comparing x-rays of patients with bloating to those without this symptom and there has been no significant difference.


It is important to identify symptoms that may lead to voluntary belching. Lactose deficiency is seen in about 30 percent of adults in the US. This specific carbohydrate malabsorption should be considered in patients presenting with excessive flatulence. Bloating may be related to the above or a perception issue.


 This blog post was contributed by Dr. Terilyn Scott-Winful, a gastroenterologist on the medical staff at Baylor Regional Medical Center at Plano.

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The Truth About Gas…More Normal Than You Think?