The average person produces 1-3 pints of gas each day which is passed as flatus or belching about 20 times daily.

The two primary sources of gas in the gastrointestinal system include air that is swallowed and gas produced by bacteria in the intestine. It is normal to swallow air with eating and drinking. It is likely that you will swallow larger amounts of air when eating and drinking quickly, chewing gum or smoking. When upright the majority of swallowed air passes back through the mouth. When lying down, swallowed air is more likely to pass into the small bowel which can result in more bloating and passage of gas through the anus.

The large intestine is home to billions of harmless bacteria, some of which help to protect you from other bacteria that can cause disease. The byproducts of carbohydrate digestion produce gasses such as carbon dioxide, hydrogen and methane. Carbohydrates such as raffinose are poorly digested and produce increased amounts of gas. Vegetables such as cabbage, brussel sprouts, asparagus, cauliflower and broccoli produce more gas. In some cases carbohydrates such as lactose can not be digested resulting in gas, bloating, abdominal pain and sometimes diarrhea. Lactose intolerance is least common in Caucasians (7-20%), but is more common in Hispanics (50%), African Americans (65-70%) and Native Americans (80-95%).

Some medical conditions impair motility within the bowel and predispose to bacterial overgrowth. These conditions include diabetes, as well as scleroderma. There also is a condition known as celiac sprue (sensitivity to gluten) that results in malabsorption of carbohydrates which may lead to increased gas production.

As gas becomes trapped in the bowel you may notice crampy abdominal pain. The majority of patients who complain of gas related symptoms do not have excessive gas production; rather they have increased sensitivity to normal amounts of gas. In a condition known as irritable bowel syndrome, patients often have increased sensitivity to gas as well as a change in their stool frequency or form (diarrhea, constipation or alterations between the two). Another condition known as functional dyspepsia is associated with recurrent pain in the upper abdomen without a structural abnormality (such as ulcer or mass) to explain the pain. Those with functional dyspepsia often have increased sensitivity to gas.

Diagnosis is typically based on history and clinical presentation. However, symptoms such as diarrhea, weight loss, abdominal pain, anemia, nausea/vomiting and lack of appetite can indicate a more serious disorder. In these cases your Borland-Groover provider may recommend further testing such as upper endoscopy or colonoscopy. In some cases, stool studies to evaluate for infection or malabsorption (measuring fat in the stool) are indicated. In other cases, testing for a sensitivity to gluten (celiac sprue) is indicated. Imaging of the bowel with barium and x-ray or CT scan may detect structural abnormalities (blind loops/fistula/partial obstructions) which could predispose to bacterial overgrowth.

Treatment involves avoiding the triggers for gas. In many cases it is useful for patients to keep a diary of which foods trigger their bloating and then institute an individualized elimination diet. If it is found that a patient has lactose intolerance a lactase supplement such as lactaid may reduce symptoms. Simithicone is an over-the-counter medication contained in Maalox, Gas-X, Mylanta and Phazyme. Simithicone causes gas bubbles to break up providing relief to some. Beano is another over-the-counter product that is effective at reducing gas after eating beans or vegetables that contain raffinose. In conditions such as irritable bowel syndrome, smooth muscle relaxants such as dicyclomine are sometimes effective in reducing sensitivity to gas. In cases of bacterial overgrowth, cyclic antibiotics may be used to decrease gas production. In celiac sprue a diet that avoids gluten containing foods may provide relief.

For further information:
American Gastroenterology Association: 
National Library of Medicine Medline Plus:


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