Definition

Intestinal gas, a buildup of air in the digestive tract, is usually not noticed until you burp or pass it rectally (flatulence). The entire digestive tract, from the stomach to the rectum, contains intestinal gas as the natural result of swallowing and digestion.

In fact, certain foods, such as beans, are not fully broken down until they reach the large intestine (colon), where bacteria act on them.

Everyone passes gas several times daily, and occasional burping or belching is normal. However, excessive intestinal gas sometimes indicates a digestive disorder.

Causes

Excess upper intestinal gas can result from swallowing more than a usual amount of air, overeating, smoking or chewing gum. Excess lower intestinal gas can be caused by eating too much of certain foods, by the inability to fully digest certain foods or by a disruption in the bacteria normally found in the colon.

Foods that cause excess gas

Foods that cause gas in one person might not cause it in another. Common gas-producing foods and substances include:

• Beans and lentils
• Vegetables such as cabbage, broccoli, cauliflower, bok choy and Brussels sprouts
• Bran
• Dairy products containing lactose
• Fructose, which is found in some fruits and used as a sweetener in soft drinks and other products
• Sorbitol, a sugar substitute found in some sugar-free candies, gums and artificial sweeteners
• Carbonated beverages, such as soda or beer

Digestive disorders that cause excess gas

Excessive intestinal gas — belching or flatulence more than 20 times a day — sometimes indicates a disorder such as:

• Celiac disease
• Colon cancer
• Constipation
• Crohn's disease (a type of inflammatory bowel disease)
• Diabetes
• Dumping syndrome
• Eating disorders
• Functional dyspepsia
• Gastroesophageal reflux disease (GERD)
• Gastroparesis (a condition in which the muscles of the stomach wall don't function properly, interfering with digestion)
• Inflammatory bowel disease (IBD)
• Intestinal obstruction
• Irritable bowel syndrome
• Lactose intolerance
• Ovarian cancer
• Pancreatic insufficiency
• Peptic ulcer
• Ulcerative colitis (a type of inflammatory bowel disease)

When to see a doctor

By itself, intestinal gas rarely indicates a serious condition. It can cause discomfort and embarrassment, but it's usually just a sign of a normally functioning digestive system. If you're bothered by intestinal gas, try changing your diet.

However, see your doctor if your gas is persistent or severe, or if it's associated with vomiting, diarrhea, constipation, unintentional weight loss, blood in the stool or heartburn.