Flatulence Physiology

NewsGuard 100/100 Score

Flatulence is a normal biological process referring to the release of flatus or gas from the digestive system via the back passage.

Causes of flatulence

Aerophagia or swallowing air

When a person ingests food or water, they also swallow small amounts of air. This air accumulates within the gut and passes into the small intestine, the rectum and finally out of the body via the anus.

Carbohydrate intake

Many of the foods we eat are carbohydrates, which contain complex sugars and plant cellulose. Some of these carbohydrates cannot be digested and absorbed by the body and are therefore passed down the intestine into the colon where they form the bulk of a stool. These are called unabsorbable carbohydrates. Such carbohydrates may undergo fermentation by bacteria in the intestine, which gives rise to gases that then get trapped in the abdomen and are passed as wind via the anus. Some examples of common foods that can cause this type of gas and flatulence include broccoli, beans, cabbage, cauliflower, pulses, lentils, raisins, prunes, applies, onions and brussel sprouts. Drinks with sorbitol (such as sugar-free products) can also lead to excessive flatulence.

Mechanism of flatulence

Sensory nerve endings present in the rectum and anal canal can detect pressure exerted by the bulk of a stool. As this pressure mounts, a person feels the urgency to pass the stool. The flatus that gathers in the lower intestine and colon also exerts pressure and triggers a need to pass wind.

Flatulence often makes a sound, as the flatus passes through the tight anal sphincter. The speed the gas is passed at, the tightness of the sphincter and other factors such as water and body fat content, determine the type and pitch of the sound. Flatulence can occur accidentally when pressure within the abdomen is suddenly raised due to coughing, sneezing, sexual intercourse or laughing, for example.

Components of the flatus

The flatus is mainly composed of nitrogen, hydrogen and carbon dioxide. The carbon dioxide content is higher among people who drink carbonated beverages regularly. The flatulence is usually only foul smelling when it contains gases that smell such as sulphur, although it is normal for the flatus to smell a bit.

Further Reading

Last Updated: Jun 13, 2023

Dr. Ananya Mandal

Written by

Dr. Ananya Mandal

Dr. Ananya Mandal is a doctor by profession, lecturer by vocation and a medical writer by passion. She specialized in Clinical Pharmacology after her bachelor's (MBBS). For her, health communication is not just writing complicated reviews for professionals but making medical knowledge understandable and available to the general public as well.


Please use one of the following formats to cite this article in your essay, paper or report:

  • APA

    Mandal, Ananya. (2023, June 13). Flatulence Physiology. News-Medical. Retrieved on May 27, 2024 from https://www.news-medical.net/health/Flatulence-Physiology.aspx.

  • MLA

    Mandal, Ananya. "Flatulence Physiology". News-Medical. 27 May 2024. <https://www.news-medical.net/health/Flatulence-Physiology.aspx>.

  • Chicago

    Mandal, Ananya. "Flatulence Physiology". News-Medical. https://www.news-medical.net/health/Flatulence-Physiology.aspx. (accessed May 27, 2024).

  • Harvard

    Mandal, Ananya. 2023. Flatulence Physiology. News-Medical, viewed 27 May 2024, https://www.news-medical.net/health/Flatulence-Physiology.aspx.


The opinions expressed here are the views of the writer and do not necessarily reflect the views and opinions of News Medical.
Post a new comment

While we only use edited and approved content for Azthena answers, it may on occasions provide incorrect responses. Please confirm any data provided with the related suppliers or authors. We do not provide medical advice, if you search for medical information you must always consult a medical professional before acting on any information provided.

Your questions, but not your email details will be shared with OpenAI and retained for 30 days in accordance with their privacy principles.

Please do not ask questions that use sensitive or confidential information.

Read the full Terms & Conditions.