What is flatulence?

Lawrence S. Friedman, MD
Flatulence or flatus describes gas that escapes from the rectum. The gas is mostly the byproduct of the fermentation of undigested food by bacteria in the colon. It contains carbon dioxide, hydrogen, and, in some people, methane. Tiny amounts of volatile chemicals produced by bacterial metabolism of residual fats and proteins are responsible for the distinctive foul odor of flatus.

Although passing gas is a natural, normal function, the resulting sounds and smells are unwelcome in social situations. The average human intestine holds 0.1 to 0.2 liters of gas, but researchers have found that in 24 hours, production of flatus averages 2 liters. This gas originates in the intestine, and its quantity and composition depend largely on the foods you eat. Studies using hydrogen breath testing have found that up to one-fifth of the complex carbohydrates eaten by average, healthy individuals is turned into gas.

Passing of gas is called flatulence. A common complaint in gas is too much flatulence. However, most people do not realize that passing gas 13 to 21 times a day is normal. Too much gas may be the result of carbohydrate malabsorption.

This answer is based on source information from the National Institute of Diabetes and Digestive and Kidney Diseases.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.