Do you know what causes intestinal gas? Simply put, gassiness is a natural part of human digestion and only becomes a problem when it makes itself known at the wrong time. Learn why you have intestinal gas and what you can do if you believe your body is producing too much of it.
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.
Many healthy individuals are concerned that they have too much intestinal gas, thinking that their digestive tract could be malfunctioning. While gas in itself is not dangerous, our inability to control its passage might have social implications.
Studies have shown that the average person generates 0.6-1.8L of gas per day. This comes from two sources, swallowed air (exogenous) and gas produced by colonic bacteria (endogenous). Intestinal gas is composed of various amounts of oxygen, nitrogen, carbon dioxide, hydrogen, and methane. Oxygen, nitrogen, and carbon dioxide come from swallowed air and hydrogen and methane are by-products of the breakdown of food residue by good bacteria (probiotics) naturally residing in the colon. Careful analysis of intestinal gas has shown that it is comprised primarily of exogenous air and only a small amount of endogenous air.
Intestinal Gas Definition and Facts
The intestine normally contains gas that is rapidly transmitted through the small intestine to the colon (large intestine). The amount of gas that is normally present is dependent on the effects of colonic bacteria on the undigested food that reaches the colon and the speed with which the gas passes through the intestines and is passed. In healthy individuals, most of the lower intestinal gas that is passed (flatus) is produced in the colon and is not transmitted from the upper intestines.
The definition of excessive intestinal gas gas varies by individual, usually based on what they have considered normal in the past. Some individuals consider excessive gas to be excessive belching or excessive burping, others excessive passing of gas (flatulence), and still others as the sensation of fullness in the abdomen. Although everyone goes through periods of excessive gas, particularly flatulence, it is only when the symptoms become chronic that people become concerned.
The most common normal cause of belching is excessive intestinal gas gas in the stomach that comes from swallowed air. However, discomfort in the abdomen for any reason also may lead to excessive belching. Therefore, belching does not always indicate the presence of excessive gas in the stomach. It is not difficult usually to differentiate between excessive gas in the stomach and other causes of excessive gas. If the problem is gas in the stomach, belching brings relief. If the cause is not gas in the stomach, belching does not bring relief.
Although excessive belching may be a sign of excessive gas, it usually is not and is rather a sign of abdominal discomfort of many causes or a learned habit of swallowing and immediately regurgitating the air as a belch. Rarely, excessive belching is due to swallowed air during acute psychiatric issues associated with anxiety.
Bloating is the subjective feeling that the abdomen feels more full than it should be, but does not necessarily mean that the abdomen is enlarged. Distention is the objective enlargement of the abdomen. Bloating is not the same as excessive intestinal gas.
Continuous distention of the abdomen usually is caused by fluid, tumors, enlarged organs, or fat within the abdomen.
Intermittent distention of the abdomen may be caused by excessive formation of intestinal gas, but also physical or functional obstruction of the intestines.
Belching and flatulence (farting or passing gas) are virtually universal. People fart on average 20 times per day. The number that defines a “lot” of burping has not been determined.
Flatulence results from the production of gas by bacteria within the intestines (usually the colon) when they digest dietary sugars and polysaccharides that reach the colon undigested.
Increased intestinal gas gas is not caused by irritable bowel syndrome (IBS) or most parasitic or bacterial intestinal infections. It also is not caused by gastritis, gastric cancer, gallstones, cholecystitis, and pancreatitis or cystic fibrosis (unless there is maldigestion of food). It also should not be confused with indigestion, which has causes other than gas.
Excessive production of intestinal gas and increased flatulence may occur because of 1) the greater ability of some bacteria to produce gas, 2) maldigestion or malabsorption of sugars and polysaccharides such as that seen in chronic pancreatitis with pancreatic insufficiency, and celiac disease, and 3) bacterial overgrowth of the small intestine.
Abdominal pain is not a common symptom of people with excessive gas, although the discomfort of bloating may be described as pain. Cramps and severe pain suggest causes other than gas, for example, intestinal obstruction that also can lead to abdominal distention and discomfort.
Remedies for truly excessive gas include changes in diet and suppression of intestinal bacteria that produce the gas. There is no evidence that digestive enzymes, activated charcoal, and simethicone (Gas-X, Mylanta, and others) relieve excessive gas.
The remedy for excessive belching not due to excessive gas is to develop new physical habits such as breathing with the mouth open.
Foul-smelling gas (flatus) is not synonymous with excessive gas. The foul smell of flatus results from the types of food that are eaten and the types of gasses produced by the bacteria in the colon, particularly gasses that contain sulfur.
You may be reassured to know that there are only two primary causes of intestinal gas—swallowed air and the bacterial breakdown of substances found in certain kinds of foods. The following information should help you pinpoint what might be causing the problem for you.
In the normal course of the day, we all swallow some air. This air is generally released through the process of burping or belching. However, this air can also make its way to the large intestine, where it is released through the rectum as flatulence.
There are things that can cause a person to swallow more air than normal.1 If any of the following apply to you, you now have something to work on:
- Eating or drinking too quickly
- Drinking carbonated beverages
- Gum chewing
- Smoking: cigarettes, cigars, and pipes
- Sucking on hard candies
- Poorly fitted dentures
Some substances in the food that we eat are not well digested and absorbed by our bodies. When these substances, mainly carbohydrates like simple sugars and starches, arrive in our large intestines, they are acted upon by bacteria within our guts. The result of this breakdown is the release of gas.
This gas is usually carbon dioxide, hydrogen, methane, and nitrogen. Although some of these gasses may be absorbed into the bloodstream and exhaled out, most of them are released through your anus.
The primary food components that can trigger the release of intestinal gas are:
- Fructose: This sugar is found in some fruits and vegetables as well as in many processed foods in the form of high fructose corn syrup. It is estimated that approximately 15% to 25% of the population has difficulty digesting and absorbing fructose, a condition called fructose malabsorption. However, eating too many fructose-containing foods in close proximity to one another can result in excessive intestinal gas even in people who do not have fructose malabsorption.
- Lactose: This sugar is found in milk and other dairy products. People who have lactose intolerance lack sufficient amounts of the enzyme lactase and thus are unable to digest lactose. When lactose is undigested, it becomes available to be acted upon by gut bacteria, with a subsequent release of gas.
- Raffinose: The high amount of this sugar in beans contributes to their well-earned gassy reputation. Raffinose is also found in vegetables such as cabbage and Brussels sprouts.
- Sorbitol: Sorbitol is naturally found in many fruits and is an artificial ingredient in many sugar-free food items. Sorbitol is classified as a polyol or sugar alcohol. Approximately 8% to 12% of the population is unable to absorb sorbitol.
Symptoms of Intestinal Gas
For most, the passage of gas through the digestive tract causes no symptoms, but some experience frequent burping or belching, uncomfortable abdominal bloating, and repeating flatus. Researchers have noted that when some individuals drink a beverage, they might swallow twice as much air as liquid, especially if drinking through a straw. As gas builds up, the abdomen may painfully distend, especially right after eating. Sometimes bloating is so severe that clothing becomes tight or may no longer fit.
Since distension of the digestive tract affects intestinal contractions, increased gas passing from the stomach into the intestine may increase normal peristalsis that, if strong enough, may cause painful cramping. Ingested gas passing through the bowel will eventually leave via the anus as flatus, as will gas produced in the colon, but it is the latter which is usually foul smelling.
Food diary. Most often, gas can be traced back to diet. Keeping a detailed food and symptom diary can help determine whether your diet is contributing to problems with gas. Nothing special is needed to keep a diary; pen and paper will do just fine. A spreadsheet is also a good way to keep track of your diet, and there are also many smartphone apps that can be used.
Ruling out disease. Gas is not usually caused by a disease or a disorder, but if gas is excessive and not caused by diet, your physician may look for other causes. After you discuss your medical history with your doctor and have a physical, you might need some diagnostic tests. Some conditions that may be associated with gas include celiac disease, diabetes, scleroderma, and small bowel bacterial overgrowth (SIBO).
Tests that may be used to evaluate excess gas include:
- Abdominal X-ray
- Upper GI series
- CT scan
- Stool tests
- Breath tests
How Is Gas Treated?
Most of the time, treatment of the symptoms of gas requires an approach that includes both dietary adjustment and medication. The most common ways to reduce the discomfort of gas are changing diet, taking medication, and reducing the amount of air swallowed.
Your doctor may tell you to eat fewer foods that cause gas. However, for some people this may mean cutting out healthy foods, such as fruits and vegetables, whole grains, and milk products. Your doctor may also suggest limiting high-fat foods to reduce bloating and discomfort. This helps the stomach empty faster, allowing gases to move into the small intestine. Unfortunately, the amount of gas caused by certain foods varies from person to person. Effective dietary changes depend on learning through trial and error how much of the offending foods one can handle.
Many non-prescription, over-the-counter medicines are available to help reduce symptoms. Such medicines include antacids with simethicone and activated charcoal. Digestive enzymes, such as lactase supplements, actually help digest carbohydrates and may allow people to eat foods that normally cause gas. Medicines available include:
- Antacids, such as Mylanta II®, Maalox II® and Di-Gel®, contain simethicone, a foaming agent that joins gas bubbles in the stomach so that gas is more easily belched away. The recommended dose is 2 to 4 tablespoons of the simethicone preparation taken 1/2 to 2 hours after meals.
- Activated charcoal tablets may provide relief from gas in the colon. Studies have shown that intestinal gas is greatly reduced when these are taken before and after a meal. The usual dose is two to four tablets taken just before eating and one hour after meals.
- For those with lactose intolerance, enzyme lactase–which aids with lactose digestion–is available in liquid and tablet form without a prescription (Lactaid®, Lactrase®, and Dairy Ease®). Adding a few drops of liquid lactase to milk before drinking it or chewing lactase tablets just before eating helps digest foods that contain lactose. Also, lactose-reduced milk and other products are available at many grocery stores.
- Bismuth subsalicylate (Pepto-Bismol®) can reduce odor that comes from the breakdown to hydrogen sulfide. It may also be helpful for some other malodorous forms of flatus. Excess or long-term use is not suggested as it can cause bismuth toxicity in patients allergic to aspirin.
- Beano®, an over-the-counter digestive aid, contains the sugar-digesting enzyme that the body lacks to digest the sugar in beans and many vegetables. The enzyme comes in liquid form. Three to 10 drops per serving are added to food just before eating to break down the gas-producing sugars. Beano has no effect on gas caused by lactose or fiber.
- Probiotics are healthy bacteria that can be found in yogurt and over-the-counter supplements. It may also improve gas symptoms by changing the bacterial flora that is responsible for producing some of the gas.
- If one experiences constipation, treatment of this disorder will be important to improve gas passage from the intestinal tract.
- As for the discomfort of gas related to failure to advance the gas through the gastrointestinal tract, gentle exercise is important to stimulate the intestines to pass the gas through. At times, abdominal massage may also improve symptoms.
Doctors may prescribe medicines to help reduce symptoms, especially for people with a motility disorder, such as IBS. If bacterial overgrowth in the small intestines is demonstrated by testing, antibiotics to reduce these bacteria may be prescribed.
Reducing swallowed air
For those who have chronic belching, doctors may suggest ways to reduce the amount of air swallowed. Recommendations are to avoid chewing gum and to avoid eating hard candy. Eating at a slow pace and checking with a dentist to make sure dentures fit properly should also help.
Although gas may be uncomfortable and embarrassing, it is not life-threatening. Understanding the causes, ways to reduce symptoms, and treatment will help most people find some relief.