why is gas created in the intestines
Gas in the gastrointestinal tract has only two sources. It is either swallowed air or it is produced by bacteria that normally inhabit the intestines, primarily the colon. Swallowed air is rarely the cause of excessive flatulence. The usual source is the production of excessive gas by intestinal bacteria. The bacteria produce the gas (hydrogen and/or methane) when they digest foods, primarily sugars and polysaccharides (e.g., starch, cellulose), that have not been digested during passage through the small intestine.