What Causes Flatulence?

Flatulence or passing wind is a normal biological process and, on average, a person passes wind around fifteen times each day. Flatulence is caused by a build up of small amounts of swallowed air and as a result of the gases produced when bacteria break food down in the gut. However, excessive flatulence can become embarrassing and people with this problem can take several measures to alleviate their symptoms.

Swallowing air

When food, water or saliva is swallowed, small amounts of air are also swallowed. A person may be unaware of how much air they are swallowing. Factors that are likely to increase the amount of air swallowed include chewing gum, sucking on hard candy, smoking, loose dentures and not chewing food well before swallowing it. Babies are even more likely to swallow air (whether breast or bottle fed) because their ability to control their breathing and ingestion is not fully developed. Drinking soda or fizzy drinks also increase the amount of carbon dioxide present in the food pipe and the stomach, although this is mostly expelled through belching or burping.

The act of swallowing air along with food is termed aerophagia (“aero” meaning air and “phagia” meaning eating). This air collects in the digestive system, is passed through the intestine and is eventually expelled as wind via the anus.

Certain foods and drinks

Some foods and drinks in particular predispose to flatulence. 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 gas. These carbohydrates are called fermentable oligo-, di- and monosaccharides and polyols (FODMAPs). Gases produced through fermentation of these carbohydrates collect in the abdomen, get passed through the intestine and are eventually expelled from the body as wind.

Examples of foods that can typically cause this flatulence include broccoli, beans, cabbage, cauliflower, pulses, lentils, raisins, prunes, apples, onions and brussel sprouts. Drinks with sorbitol (such as sugar-free products) can also lead to excessive flatulence.


Several diseases and disorders can lead to flatulence. Some of these include:

  • Chronic or recurrent constipation
  • Irritable bowel syndrome, which is typically characterized by recurrent bouts of abdominal cramps, bloating, constipation and diarrhea
  • Coeliac disease, which describes an intolerance to a component in wheat, rye and barley called gluten. The gluten aggravates the small intestine, leading to abdominal symptoms such as bloating, pain, diarrhea and flatulence.
  • Lactose intolerance, a condition that occurs in people who are deficient in the enzyme required to break down the lactose present in milk and other dairy products. This leads to bloating, pain, diarrhea and flatulence.
  • Gastroenteritis or infection of the intestine and stomach caused by various bacteria which leads to diarrhea, vomiting, inflammation, abdominal cramps and bloating, as well as flatulence.

Further Reading

Last Updated: Feb 26, 2019

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.


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