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What is Intestinal Gas?
Many normal, healthy people are concerned that they have too much intestinal gas, believing that their digestive tract could be malfunctioning. Although some fear a serious ailment is present, fortunately, this is rarely the case. While gas in itself is not dangerous, its consequences may have social implications due to our inability to control its passage.
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. Because of its symptom severity, sufferers could be overly concerned regarding its seriousness.
Everyone has gas in the intestinal tract, although the volume varies from person to person. Studies on young adults have shown that the average person generates 1-3 pints of gas per day. This gas comes from two sources: exogenous, or swallowed air, and endogenous, gas produced by colonic bacteria. Intestinal gas is composed of various amounts of oxygen, nitrogen, carbon dioxide, hydrogen, and methane. Oxygen, nitrogen, and carbon dioxide come from swallowed air. Bacteria naturally residing in the colon produce hydrogen and methane as by-products of breaking-down food residue. Careful analysis of intestinal gas has shown that about 90% is ingested air and only 10% forms in the intestine.
Although less than 1% of gas is odorous, intestinal bacteria produce several sulphur-containing compounds that are the primary odour culprits. The human nose can detect hydrogen sulphide in concentrations as low as one-half part per billion, so passing even a very small amount of this gas could draw attention!
How is gas passed from the intestine?
Gas releases from the intestinal tract via the mouth by belching, or via the rectum as flatus. A normal individual emits flatus about 12-25 times per day. In the typical situation, swallowed air remains in the stomach for a while and then passes out of the stomach on its way through the digestive tract in small amounts at regular intervals. It passes rapidly through the small intestine propelled by peristalsis, the normal rhythmic contractions of the digestive tract. Usually this process does not cause any uncomfortable symptoms. Once gas enters the colon, its propulsion slows and eventually the anus releases it in small amounts.
Almost no air is swallowed during sleep, but gas passes out of the colon during sleep, thus at the beginning of the day there is minimal gas in the intestine, and then the cycle continues as it accumulates throughout the day. Many factors influence gas passage and these include the amount of swallowed air, the nature and frequency of meals, and the motility of the bowel, which can be affected by food, drugs, and stress.
How may intestinal gas cause symptoms?
For most people, passage of gas throughout the digestive tract causes no symptoms, but some people experience frequent burping or belching, abdominal bloating or distension, and increased flatus. Swallowed air trapped in the stomach releases by burping or belching and sometimes during swallowing, as this action opens the lower esophageal sphincter, which releases the air from the stomach. Researchers have noted that some individuals, when drinking a cup of water, actually swallow twice as much air as water ingested, especially when drinking through a straw.
Since distension of the intestine initiates intestinal contractions, increased gas passing from the stomach into the intestine may increase normal peristalsis, which if strong enough, may cause painful cramps. If air is trapped in the small bowel, or more likely in the colon, then bloating and distension could occur. The distension may stimulate spasmodic contractions that prevent propulsive movement of gas and thus cause further gas build-up and distension.
Ingested gas passing through the bowel will eventually leave as flatus, as will gas produced in the colon, but it is the latter which is usually foul smelling.
How is symptomatic intestinal gas managed?
There are things you can do to reduce air intake to the digestive system, and gas-producing foods you can avoid.
Such things as gum chewing, poor fitting dentures, a chronic postnasal discharge, chronic pain, and anxiety or tension, all cause increased air swallowing. Gulping of food and mashing food down with liquids also increases air ingestion. Since sipping hot drinks allows more air intake, you might want to let your beverages cool down somewhat before drinking. When chewing some raw foods, such as lettuce and cabbage, air traps around the crushed food particles and progresses through the digestive system.
There is little gas production in the small intestine because bacterial concentration is low. The gas-producing colonic bacteria thrive on foods containing poorly digested carbohydrates (starches and sugars). When these foods reach the colon, smelly gas forms as the bacteria ferment them. This fermentation is similar to the production of bubbles in the fermenting of grapes into champagne.
The most common source of indigestible carbohydrate is lactose, found in such dairy products as milk, and milk-based cheese products. Cream-based and aged cheeses contain only very small amounts of lactose. About 20% of Caucasians and most non-Caucasians, lack the enzyme, lactase, needed by the body to break apart and absorb lactose. Lactase deficiency is particularly common in blacks, Asians, and those of Mediterranean origin. If you are lactose intolerant, you can obtain commercial products containing the enzyme, lactase, so you do not have to avoid this food group.
The next most common source of gas is beans, which contain the complex carbohydrates raffinose and stachyose (also found in some other foods). The intestine cannot absorb these carbohydrates because the enzymes necessary for their digestion do not exist in humans. Certain colonic bacteria are capable of digesting these substances; however, the by-products of their digestion are hydrogen, methane, and carbon dioxide gases. Some people find the commercial product, Beano® helpful in reducing the amount of gas produced.
Besides beans and lactose, several other vegetables and fruits are gas producers but not everyone reacts in the same manner to these foods. Eliminating these foods from the diet simply because they produce gas is not recommended.
It may be necessary to use medication for a while, either to decrease bowel spasms or induce more normal propulsive bowel motility. In these instances, antispasmodics and motility regulators may be helpful. Reducing stress and anxiety in your life may also be helpful.
Intestinal gas is generally more of an annoyance than a serious medical problem for most individuals. However, if you experience ongoing excessive gas accompanied by other symptoms, or gas not relieved by dietary and/or lifestyle changes, then consult your physician.
Helpful Hints for Gas Reduction
Do:
try to limit air swallowing
eat slowly
have loose dentures refitted
treat post-nasal drip
increase physical activity
reduce your lactose load (if intolerant)
increase fibre in your diet
pre-soak beans at least 4 hours in water and then drain and rinse before cooking thoroughly in fresh water
Are you taking prescription medication for any of the following stomach problems/symptoms:
Stomach pain or discomfort
Heartburn
Sour taste in mouth/acid regurgitation
Excessive burping/belching
Increased abdominal bloating
Nausea
Early satiety
If you answer yes to any one of the symptoms listed above then take this test to see if your current medication is adequately controlling your stomach symptoms.
The PASS Test
PPI* Acid Symptom Suppression Test
*PPI is short for proton pump inhibitor, a class of medication used to suppress the acid in your stomach. These include Losec®, Nexium®, Pantoloc®, Pariet™, and Prevacid®.
