Gas, sometimes a subject of jokes or ridicule (a favorite among kids), is more often a source of embarrassment and discomfort. Gas may be different things to different people. "Passing gas" or flatus/flatulence may be odoriferous or noisy, has a different origin than belching gas, or "gas-bloating." These will each be discussed separately.

The medical term for this is eructation. An occasional belch is normal, there are no well defined criteria outlining how much belching is abnormal belching. A patient seeks medical attention when he/she believes it is excessive or constant.

Cause:  Gas that is belched is essentially all from the atmosphere, that is, swallowed air.

There is virtually no abnormal gas production in the stomach that contributes to belching. The composition of burped gas is primarily nitrogen and oxygen, the same as air. Air is normally swallowed when saliva, liquids and food are swallowed. It is estimated that an average person swallows about 2,500 cc (two and a half liters) a day. Much of the air is subtly brought back up, often without awareness (or perhaps it is so routine, it is ignored). Some people swallow significantly more air while sucking on candy, chewing gum, smoking, or when under stress. Patients with ulcers, reflux/heartburn (GERD) and other disorders of the upper GI tract may swallow excess air and have belching symptoms.

Treatment:  Evaluation of the upper GI tract with endoscopy may be indicated to look for structural factors like large hiatal hernias and for conditions such as reflux, ulcers, etc. If one of these disorders is detected, specific treatment would be rendered.

In most people, there is no disease process or significant abnormality with the structure of the esophagus; the problem is too much air swallowing. Air swallowing can become a habit, often unrecognized by the individual.

Recommendations (also see below): Don’t smoke or chew tobacco, don’t chew gum, don’t suck on hard candy, don’t drink carbonated beverages (pop, beer, etc). Simethicone is an anti-gas liquid found in many over-the-counter products (Gas-X, Mylanta II, Maalox plus and others) and can be helpful. Ultimately, the key to success, although admittedly sometimes difficult to accomplish, is DO NOT SWALLOW AIR!

The occasional feeling of distention in the abdominal area is a normal sensation for most people, especially when it occurs after eating. If it is frequent or associated with significant discomfort, it may be brought to the attention of the family, friends, or doctor.

Cause: The exact cause of bloating can be elusive. Although many people intuitively believe the bloating to represent build-up of intestinal gas, it is difficult to prove this with tests like X-rays and analysis of gas volumes. Even with more sophisticated evaluations with CT scans, using computer programs to quantify the gas present in bloated patients, no significantly abnormal gas accumulation was demonstrated.

The "cause" of the bloating may actually be several:

• Gas could possibly play a role when other factors are added in. 

• One study showed that patients with bloating unconsciously protruded their abdomen more. When pointed out, most of these people could reduce the size of "the stomach" with conscious effort.

• Some patients have abnormal sensation of abdominal processes. In irritable bowel syndrome, patients sense normal gas and intestinal activity when they shouldn’t. This causes them to feel bloated and uncomfortably.

Treatment:  Attempts should be made to reduce gas, since even "normal" amounts of gas may be sensed and cause symptoms in some people. Avoiding air swallowing may help (see recommendations above and below). Foods can be gas-forming, especially milk and milk products if your body cannot digest milk sugar (see below for more details on gassy foods). Simethicone, on over-the-counter anti-gas product can help in some people. It works by reducing the surface forces of bubbles, breaking them up. Simethicone is found in several products like Gas-X, Mylanta II and others. Activated charcoal can be used to adsorb gas and is used successfully in some patients. Treatment of underlying irritable bowel syndrome should be addressed, when present. Newer medications, which act on Serotonin, can alter gut function and secretion and improve symptoms. Certain medical conditions can be associated with bloating. Celiac sprue, pancreatic disease, and Crohn’s Disease should be looked for in some individuals.

Cause:  This type of gas can be annoying and frankly embarrassing for those that suffer with it. In studies performed at the University of Minnesota, it was shown that healthy adults normally pass gas and they do so approximately 10 times per day. Passing gas becomes a problem for those who pass excessive amounts of gas, cannot control the "normal" gas passed, or produce gas that is odiferous.

In terms of volume, passed gases are mainly odor-free ones like nitrogen, carbon dioxide, hydrogen, and methane. Nitrogen is the main gas in air (oxygen makes up only 21% of air). Thus, the nitrogen in flatus comes from swallowed air. Nitrogen gas is not well absorbed in the intestine – if swallowed it must be either belched up or it will come through as flatus.

The other gases are produced in the large intestine (colon) by bacteria. All humans have large numbers and many species of bacteria that normally reside in the colon. These bacteria essentially live on the material that passes through the colon, such as food that was not digested and absorbed in the small intestine. Some of the products of the bacteria, as they metabolize their food, are gases they release into the colon (hydrogen, carbon dioxide, and methane). The primary food substance ‘enjoyed’ by bacteria is carbohydrate. Most carbohydrates require human intestinal breakdown into small fragments to be absorbed. Some carbohydrates cannot be adequately broken down and when eaten, will produce gas.

Three examples of carbohydrates that cause gas:

1. Beans and some other vegetables have complex carbohydrates that humans lack the proper enzyme to digest.

2. Some people do not have the enzyme lactase, which breaks down milk sugar, lactose. When milk, cheese or ice cream is ingested, lactose sugar travels through into the colon where bacteria metabolize it, and gives us gas!

3. Fructose is a simple sugar that does not require an enzyme to absorb it, but, it is still not absorbed efficiently or completely. Fructose is found mainly in fruits, vegetables, and soft drinks.

 

Treatment of Gas:   Prevention is the best treatment. To summarize, gas is caused by swallowing air and by bacteria producing gas in our colon by digesting foods we have eaten but not absorbed.

• Avoid chewing gum.

• Avoid sucking on candy.

• Avoid smoking.

• Avoid chewing tobacco.

• Avoid carbonated beverages.

• If you have dentures, make sure they fit well.

• Treat conditions like reflux/heartburn that can contribute to air swallowing.

• Avoid consciously try not to swallow air.

• Are you lactose intolerant?

A "milk challenge test" may be a starting point to determine if milk sugar (lactose) is the problem. Drink a large glass of milk – if gas, bloating, and diarrhea develop within a few hours it is likely you are milk intolerant. You then should avoid milk, cheese, and ice cream, and frozen yogurt. Refrigerated yogurt is OK to eat; the yogurt culture breaks down most of the lactose. An alternative to avoiding milk products is to take a lactase supplement with milk. Over-the-counter products like Lactaid ultra, Lactrase, and Dairy-ease can provide enough lactase to reduce gas and other symptoms of milk intolerance. With a glass of milk, try taking 2 lactase tablets as you start drinking and 2 more about half way through the glass.

• Avoid or reduce certain carbohydrates.

You may have to experiment on your own to determine which foods you are sensitive to.

Suggestions include: fructose containing foods like fruit, honey, vegetables, soft drinks. Complex carbohydrates like beans, broccoli, cauliflower, cabbage, and mushrooms.

• Avoid fiber.

Fiber is basically unabsorbable plant carbohydrate. Bacteria can digest some of the fiber and release gas. Fiber supplements (Metamucil, Perdiem, Konsyl, Citrucel, and others), whole grains, vegetables and fruits are the main sources of fiber.

• Over-the-counter gas remedies like Simethicone or Beano can be helpful in some people.

 

• Certain medical conditions can cause malabsorption (reduced absorption of food). Gas can be a symptom of these disorders which include: celiac sprue, pancreatic disease, diverticulosis that causes overgrowth of bacteria, and short bowel syndrome from previous surgery.

• Anxiety and Irritable Bowel Syndrome – mainly cause gas via excessive air swallowing.

 

Foods and Flatus (gas)

Normoflatulogenic Foods:  usually not gassy

• Beef, chicken, fish, lettuce, olives, grapes, eggs, gelatin.

Moderately Flatulogenic:  somewhat gassy

• Foods that contain wheat and wheat products, including cereals, breads, pastries, bagels, and pretzels. 

• Potatoes, citrus fruit, and carbonated beverages.

High Flatulogenic Foods:  very gassy

• Milk, ice cream, and cheese.

• Onions, carrots, raisins, bananas, prunes.

• Most beans (baked, lima, soy, and others).

• Cabbage, radishes, cauliflower, broccoli, asparagus, sauerkraut, brussel sprouts.

• Pretzels, bagels, and wheat germ.

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