Flatulence

Causes of flatulence

There are several natural causes of flatulence. Flatulence can also be caused by some health conditions that are related to the digestive system.

Swallowing air

It is perfectly normal to swallow air while breathing and eating. However, it is easy to swallow a lot more air than usual without realising it. This can cause excessive flatulence.

Excess air can be swallowed by:

  • chewing gum
  • smoking
  • sucking on pen tops or hard sweets
  • having loose fitting dentures
  • not chewing food slowly and thoroughly (swallowing large pieces of food will result in you swallowing more air)

Hot and fizzy drinks also increase the amount of carbon dioxide in your stomach, although this is more likely to cause belching rather than flatulence.

Food and drink

Much of the food we eat is carbohydrate. Carbohydrates are made up of long chains of sugar molecules. Some carbohydrates cannot be digested and absorbed by the intestines and pass down into your colon. These are known as unabsorbable carbohydrates, or fermentable oligo-, di- and monosaccharides and polyols (FODMAPs). 

Your colon contains more than 500 different types of bacteria. The bacteria start to break down the carbohydrates and in the process produce gas, which is released as flatulence.

Foods that contain a high amount of unabsorbable carbohydrates include:

  • beans
  • broccoli
  • cabbage
  • cauliflower
  • artichokes
  • raisins
  • pulses
  • lentils
  • onions
  • prunes
  • apples
  • Brussels sprouts

Other foods and drinks containing a sweetener called sorbitol (such as sugar-free gum or slimming products), or a type of sugar called fructose (such as fruit juice), can also cause flatulence.

Certain foods, such as cabbage or onions, can lead to the production of gases containing sulphur, which can result in foul smelling wind.

However, the production of smelly wind can vary from person to person depending on what you eat, so it is up to you to work out which foods cause the most smell.

Health conditions

Health conditions that can cause symptoms of flatulence include:

  • constipation 
  • irritable bowel syndrome (IBS) – a common digestive condition, which can cause stomach cramps, bloating, diarrhoea and constipation
  • coeliac disease – an intolerance to a protein called gluten, found in wheat, rye and barley
  • lactose intolerance – where the body is unable to break down lactose (a natural sugar found in milk and dairy products) and cannot absorb it into the blood
  • gastroenteritis – a stomach and bowel infection
  • malabsorption – where the intestines are unable to absorb nutrients properly
Last updated: 09 October 2014

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