Undigested food, swallowing too much air while consuming food and beverages, or digestive illnesses or disorders often cause excess gas, explains Mayo Clinic. Excess gas stems from either the lower intestine or upper intestine depending upon the cause.
Individuals who swallow too much air experience excess upper intestinal gas as a result, according to Mayo Clinic. Excess gas from the lower intestines results from bacterial reactions indicating that food did not break down or digest until it reached the colon. The composition of lower intestinal gas includes carbon dioxide, hydrogen and sometimes methane.
Foods that do not digest or break down easily cause excess gas from the lower intestines, according to Mayo Clinic. Gas-producing foods include dairy products that contain lactose, fructose and sorbitol found in fruits and sweeteners, and beans and lentils.
Certain digestive disorders and illnesses can cause excess gas that results in flatulence or belching more than 20 times daily, explains Mayo Clinic. Individuals with a peptic ulcer, food allergy or food intolerance may release more gas than usual. Individuals with celiac disease, gastroesophageal reflux disease, irritable bowel syndrome or gastroparesis commonly have excess gas from the lower intestines, too. People who are lactose intolerant commonly produce more gas when exposed to dairy products.