Gas, also called flatus or flatulence, is air in the intestine that is passed through the rectum. Air that is passed from the digestive tract through the mouth is called belching.
Gas is formed in the intestines as food is being digested. Gas can make you feel bloated, which may cause crampy or colicky abdominal pain.
Gas can be caused by any of the following:
Birrer RB. Irritable bowel syndrome. Dis Mon. 2002; 48(2): 105-143.
Lovelace HY. Diagnosis, symptoms, and calcium intakes of individuals with self-reported lactose intolerance. J Am Coll Nutr. 2005; 24(1): 51-57.
Andrès E. Food-cobalamin malabsorption in the elderly. Am J Med. 2002; 113(4): 351-352.