Bloating, Gas and Distension
Bloating refers to a sensation of abdominal fullness, pressure, or a sensation of trapped gas. Bloating and distension (the feeling your abdomen is measurably larger and protruding) has been reported in up to 20-30% of the general population and in up to 96% of patients with irritable bowel syndrome (IBS). One study found that only 50-60% of patients with bloating report abdominal distension, so these conditions are not always one and the same (i.e. you can have one condition, but not always the other).
Why?
Abdominal bloating and distension can develop for multiple reasons, including food intolerances, a previous infection that change the intestinal microbiome, disordered visceral sensation (changes in the way your gut responds to things moving through it) and delayed intestinal transit time (the time it takes for things to move through the bowel).
Why is this?
It may be that there is an increased sensitivity to the gas. This may be in conditions such as irritable bowel syndrome (IBS) or functional dyspepsia.
It may be that there is increased gas production. This could be from swallowing too much air, poor digestion of sugars allowing increased gas production during the digestion process, too many bacteria in the gastrointestinal tract (small intestinal bacterial overgrowth or SIBO), or other conditions.
What else?
It may be important to check for other potential causes for bloating, gas and distension such as:
-Food intolerances or allergies including Coeliac disease (gluten allergy).
-Low levels of enzymes to digest sugars (we can biopsy to measure lactase, maltase and sucrase which digest lactose, maltose and sucrose respectively).
-Problems with emptying out the bowels (stool).
-Decreased pancreatic function.
-Increased fluid in the abdomen (ascites).
-Lumps in abdominal organs including the colon and excluding inflammation.
Where does the gas come from?
The volume of gas in the intestinal tract is approximately 200mL. Gas in the stomach is mainly oxygen and nitrogen. Flatus (farting) from the bottom has less oxygen and more methane.
The gas gets inside in 2 main ways:
- Aerophagia
Swallowing air is a major source of air in the stomach. It is normal to swallow some air when eating. You may swallow larger amounts of air when eating food quickly, gulping liquids, chewing gum, or smoking. A lot of this gas escapes when belching (burping). If you lie down, a lot of gas may move into the small intestine and pass as flatus.
- Production of within the GI tract
Bacteria in the gut (there are billions) help to digest foods and some can release gas as a by-product. Certain carbohydrates are incompletely digested by enzymes in the stomach and intestines, allowing bacteria to digest them. For example, cabbage and brussels sprouts are particularly poorly digested, and undigested sugars then pass to the colon, where they are broken down, releasing carbon dioxide, hydrogen, and methane. Some small components of gas have an unpleasant odor, including trace amounts of sulfur. In particular, in some people and up to 30% of Asian people, there can be an element of lactose intolerance – inability to digest lactose (milk, chocolate, creams, soft cheeses).
If you want more specifics on the types of gas:
-Carbon dioxide (CO2): This gas comes from digestion of fat and protein from bacterial fermentation.
-Hydrogen (H2) is both produced and consumed by faecal bacteria. Small intestinal carbohydrate malabsorption leads to increased delivery of carbohydrates (sugars) to the colon and increased H2 gas production.
-Methane – Like H2, methane is exclusively a product of bacterial metabolism. The main methanogenic bacterium is Methanobrevibacter smithii.
Farting:
The volume of gas passed via farting varies from about 500 to 1500 mL per day. The frequency of farting varies between 10 and 20 times per day in healthy people.
Studies have shown that people who complain of bloating may actually have the same amount of gas inside as people that have no symptoms.
So what next?
Successful treatment involves identifying the cause, assessing severity, discussing and trialling potential treatments and what you can expect from these.
Tests or investigations:
This may involve things such as blood or stool tests (check for infection and inflammation), breath tests, gastroscopy, colonoscopy or scans. However, every case is different and we will go through things individually, and a few, if any tests may be required in some cases.
Treatments may include:
This depends on what is found, but if IBS or functional dyspepsia, may include:
-Low FODMAP (see further article for more information).
-Reduction in lactose or taking lactase (enzyme containing capsules) to help digest lactose when you eat it.
-Changes in behaviour and posture, including breathing, swallowing, increase in exercise and erect posture.
-Changes in medicines if they are slowing down digestion (such as anticholinergic agents, opioids, and calcium blockers).
-Over the counter medications including defoaming agents (De-gas) containing simethicone, Iberogast (herbal supplement which may improvement discomfort but not really bloating).
-Antispasmodics to reduce discomfort.
-Biofeedback/neuromodulator medicines – changing the way your body responds to the gas.