Alternative names
Aerophagia, excessive gas, flatulence or “farts”.

What is flatus?
Flatus (flatulence) is air or gas in the intestine that is released through the rectum. This gas consists mainly of the odourless gas carbon dioxide. Small amounts of other gases are present, such as methane and hydrogen sulphide. The unpleasant smell of intestinal gas is a result of the hydrogen sulphide or other compounds. These other compounds are mostly amines, which are produced when proteins are broken down in the colon. The amines can be particularly offensive.

What causes flatus?
When bacteria begin to break down undigested food in the large intestine or colon, gas is formed. This causes the intestine to distend (swell), which can cause cramping pain. If the intestinal wall is inflamed, it can become more sensitive than usual to normal amounts of flatus.

Even though it can cause discomfort, excessive gas is usually not a serious symptom.

There are many causes of flatus and they may vary depending on your age, gender, and associated complaints. Some of the more common causes include:

  • Eating non-digestibl  
  • Eating foods that your body cannot tolerate (as in lactose intolerance which occurs when you lack the enzyme which digests lactose or milk sugar).  
  • Eating beans. There are carbohydrates in beans that cannot be digested by our enzymes so the bacteria in the colon have to break it down. The result is colonic gas.  
  • Acute pancreatitis.  
  • Irritable bowel syndrome.  
  • Malabsorption (which occurs when your intestine is not able to absorb nutrients) often accompanied by diarrhoea.  
  • Use of antibiotics.

Who gets flatus?
Anyone can get flatus. Fibre is the main cause of flatus and since fibre is necessary in a healthy diet, flatus can be seen as a sign of good health! It has been estimated the average healthy young male passes excess gas thirteen times a day.

How is flatus diagnosed?
If flatus is one of several symptoms, your doctor might need to consider the possibility of illnesses such as inflammatory bowel disease. In this case, your doctor will probably ask questions about your medical history, such as what your eating habits are like and whether you experience any other symptoms, such as diarrhoea, abdominal pain or bloating.

Diagnostic tests that may be performed to rule out serious problems include:

  • barium swallow X-ray  
  • barium enema X-ray  
  • blood test  
  • cholecystogram or gallbladder X-ray  
  • sigmoidoscopy or proctoscopy

Can flatus be prevented?
Intestinal gas may increase temporarily after starting a high-fibre diet. The condition usually disappears on its own once your body has adjusted to the new diet. Also try the following:

  • Do not eat milk products for a week as you might be lactose-intolerant. Avoiding rich foods, fizzy drinks and beer.  
  • To decrease the presence of foul-smelling amines in the intestine, you could decrease the amount of protein, primarily meat, in your diet. However, it is advisable to see a nutritionist before doing this.  
  • Avoid foods like navy beans, cabbage, brussel sprouts, cauliflower, broccoli, turnips, cucumbers, radishes, onions, and melons.  
  • Eat slowly and chew your food thoroughly.  
  • Increase your intake of chlorophyll. Chlorophyll is found in leafy green vegetables, such as spinach.

When to call the doctor
See your doctor if you have excessive flatus or if it is accompanied by pain.

Johns Hopkins patient information

Last revised: December 8, 2012
by Armen E. Martirosyan, M.D.

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