CausesBy Mayo Clinic staff
Gas forms when bacteria in your colon ferment carbohydrates that aren't digested in your small intestine. Unfortunately, healthy, high-fiber foods are often the worst offenders. Fiber has many health benefits, including keeping your digestive tract in good working order and regulating blood sugar and cholesterol levels. But fiber can also lead to the formation of gas.
High-fiber foods that commonly cause gas and gas pains include:
- Whole grains
- Beans and peas (legumes)
Fiber supplements containing psyllium, such as Metamucil, may cause such problems, especially if added to your diet too quickly. Carbonated beverages, such as soda and beer, also are causes of gas.
Other causes of excess gas include:
- Swallowed air. You swallow air every time you eat or drink. You may also swallow air when you're nervous, eat too fast, chew gum, suck on candies or drink through a straw. Some of that air finds its way into your lower digestive tract.
- Another health condition. Excess gas may be a symptom of a more serious chronic condition. Examples include diverticulitis or an inflammatory bowel disease, such as ulcerative colitis or Crohn's disease.
- Antibiotics. In some cases of excess gas, antibiotic use may be a factor because antibiotics disrupt the normal bacterial flora in your bowel.
- Laxatives. Excessive use of laxatives also may contribute to problems with excess gas.
- Constipation. Constipation may make it difficult to pass gas, leading to bloating and discomfort.
- Food intolerances. If your gas and bloating occur mainly after eating dairy products, it may be because your body isn't able to break down the sugar (lactose) in dairy foods. Many people aren't able to process lactose efficiently after age 6, and even infants are sometimes lactose intolerant. Other food intolerances, especially to gluten — a protein found in wheat and some other grains — also can result in excess gas, diarrhea and even weight loss.
- Artificial additives. It's also possible that your system can't tolerate artificial sweeteners, such as sorbitol and mannitol, found in some sugar-free foods, gums and candies. Many healthy people develop gas and diarrhea when they consume these sweeteners.
- Gas in the digestive tract. National Digestive Diseases Information Clearinghouse. http://digestive.niddk.nih.gov/ddiseases/pubs/gas. Accessed March 4, 2011.
- Living with gas in the digestive tract. American Gastroenterological Association. http://www.gastro.org/patient-center/digestive-conditions/gas-in-the-digestive-tract. Accessed March 4, 2011.
- Gas-related complaints. The Merck Manuals: The Merck Manual for Healthcare Professionals. http://www.merckmanuals.com/professional/sec02/ch008/ch008d.html . Accessed March 4, 2011.
- Abraczinskas D, et al. Intestinal gas and bloating. http://www.uptodate.com/home/index.html. Accessed March 4, 2011.
- Picco MF (expert opinion). Mayo Clinic, Jacksonville, Fla. March 15, 2011.