Flatulence: Gas buildup in the colon
Intestinal gas is typically caused by the fermentation of undigested food, such as plant fiber, in the colon. Gas can also form when your digestive system doesn't completely break down certain components in foods, such as gluten or the sugar in dairy products and fruit.
Other sources of intestinal gas may include:
- Food residue in your colon
- Changes in intestinal bacteria due to antibiotics or other medications
- Poor absorption of carbohydrates, which can upset the balance of helpful bacteria in your digestive system
- Swallowed air that moves to your colon
- Constipation, since the longer food waste remains in your colon, the more time it has to ferment
Sometimes, gas indicates a digestive disorder, such as irritable bowel syndrome or lactose intolerance.
To prevent excessive gas, it may help to:
- Avoid the foods that affect you most. Common offenders include beans, peas, lentils, cabbage, onions, broccoli, cauliflower, whole-wheat bread, mushrooms, and beer and other carbonated drinks. If dairy products are a problem, try low-lactose or lactose-free varieties.
- Eat fewer fatty foods. Fat slows digestion, giving food more time to ferment.
- Temporarily cut back on high-fiber foods. Fiber aids digestion, but many high-fiber foods are also great gas producers. After a break, slowly add fiber back to your diet. Add products such as Beano to high-fiber foods to help reduce the amount of gas they produce.
- Eat slowly. Try to make meals relaxed occasions. Eating when you're stressed or on the run can interfere with digestion.
- Get moving. It may help to take a short walk after eating.
- Try an over-the-counter remedy. Some products such as Lactaid or Dairy Ease can help digest lactose. Products containing simethicone (Gas-X, Mylanta Gas) haven't been proved helpful, but they're commonly used to help break up bubbles in gas.
When to see your doctor
Bouts of excess bloating, belching and gas often resolve on their own. Consult your doctor if your symptoms don't improve with changes in eating habits or you notice:
- Persistent or severe abdominal pain
- Bloody stools
- Changes in the color or frequency of stools
- Unintended weight loss
- Chest pain
These symptoms could signal an underlying digestive condition. Intestinal symptoms can be embarrassing — but don't let embarrassment keep you from seeking help. Treatments are available.
April 15, 2014
See more In-depth
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- Gas-related complaints. The Merck Manuals: The Merck Manual for Health Care Professionals. http://www.merckmanuals.com/professional/gastrointestinal_disorders/symptoms_of_gi_disorders/gas-related_complaints.html. Accessed Dec. 20, 2013.
- Living with gas in the digestive tract. American Gastroenterological Association. http://www.gastro.org/patient-center/digestive-conditions/gas-in-the-digestive-tract. Accessed Dec. 20, 2013.
- Gas in the digestive tract. National Digestive Diseases Information Clearinghouse. http://digestive.niddk.nih.gov/ddiseases/pubs/gas. Accessed Dec. 17, 2013.
- Abraczinskas D, et al. Intestinal gas and bloating. http://www.uptodate.com/home. Accessed Dec. 17, 2013.