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Flatulence (Gas) (cont.)

What is flatulence or intestinal gas?

The definition of flatulence is gas (generated during digestion or waste gases), usually in excess, that is present in the intestinal tract and usually removed from the body by passing out through the anus, often accompanied by sound and odor when the gas is expelled by the body. Common terms for flatulence include terms such as farts, breaking wind, and passing gas. Some individuals include belching (passing gases from the stomach through the mouth) under flatulence.

Also, a condition termed "vaginal flatulence" is the release of air trapped in the vagina during or after sexual intercourse that sounds like flatulence when expelled from the vagina, but does not contain waste gases and has no specific odor. It is not flatulence, but termed so because of the sound emitted when the air escapes the vagina.

Most people produce about 1-3 pints of gas a day, and pass gas about 14 times a day. Flatulence itself, although not life-threatening, can definitely cause social embarrassment. This embarrassment is often the reason why people might seek medical help for excessive gas.

  • The primary components of gas (known as flatus, pronounced FLAY-tuss) are five odorless gases: nitrogen, hydrogen, carbon dioxide, methane, and oxygen.
  • The characteristic smelly odor is attributed to trace gases such as skatole, indole, and sulfur-containing compounds.
  • The flammable character of flatus is caused by hydrogen and methane. The proportions of these gases depend largely on the bacteria that live in the human colon that digest, or ferment, food that has not been absorbed by the gastrointestinal (GI) tract before reaching the colon.
  • An estimated 30-150 grams of this undigested food reach the colon in the form of carbohydrate every day. But this amount can vary with diet and how well the GI tract is functioning.

Flatulence (Gas) Causes

Patient Comments

Excess gas in the digestive tract (esophagus, stomach, small intestine, and colon/large intestine) can come from two sources: 1) increased intake of gas, for example, from air swallowed; or 2) increased production of gas as certain undigested foods are broken down by harmless bacteria normally found in the colon.

Swallowed Air

Swallowed air (aerophagia) can occur with improper swallowing while eating or even unconscious swallowing of air out of habit.

  • Activities that cause a person to swallow air include rapid drinking, chewing gum, use of tobacco products, sucking on hard candy, drinking carbonated beverages, loose dentures, and hyperventilation.
  • Most people burp or belch to expel this excess swallowed air. The remaining gas moves into the small intestine. The air moves along to the large intestine for release through the rectum.
  • Analysis of the gas can help determine if it originated from aerophagia (mostly nitrogen, also oxygen, and carbon dioxide) or GI production (mainly carbon monoxide, hydrogen, and methane).

Lactase Intolerance

Another major source of flatulence is lactose intolerance, which results in a decreased ability to digest lactose, a natural sugar found in milk and other dairy products such as cheese and ice cream and in certain processed food such as bread, cereal, and salad dressing. This flatulence is often associated with diarrhea and cramping but can appear as only gas. Many people normally have low levels of the enzyme lactase needed to digest lactose after childhood. Also, as people age, their enzyme levels decrease. As a result, over time people may experience increasing amounts of gas after eating food containing lactose.

Medically Reviewed by a Doctor on 8/11/2015

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Flatulence (Gas) - Causes

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