Bloating and Distension in IBS

In the not-so-distant past, medical professionals often thought that the bloating and distension frequently reported by people with irritable bowel syndrome (IBS) were just products of an overly active imagination. If you've felt that increasing pressure and had to loosen your belt as it gets later in the day, you know how off base these doctors were.

Bloating

Bloating is defined as the perception of increased pressure in the abdomen. Bloating is reported more frequently by women than men, but this may be due to differences in how the symptom is perceived by the different genders.

Bloating is a fairly universal phenomenon, with an estimated 16% to 31% of the general population having it at some point. The numbers skyrocket when you talk to people with IBS—up to 90% of them report bloating, and the percentage is even higher for those with constipation-predominant IBS (IBS-C).

While it's most common in IBS-C and mixed-type IBS, about half of those with diarrhea-predominant IBS (IBS-D) experience it, too. It's common enough that you might be surprised that bloating isn't even listed as part of the Rome IV criteria for diagnosing IBS.

Distension

Distension differs from bloating in that it involves a measurable change in the circumference of the abdomen. Distension typically gets worse as the day wears on. You may also find that your abdomen gets more distended after you have eaten.

It's estimated that approximately half of all IBS patients experience distension. Distension and bloating often are experienced simultaneously, but it is thought that they result from different bodily processes.

Causes

Contrary to what you might think, excessive gas isn't always the reason behind bloating and distension—studies show it's only responsible for about 25% of the bloating associated with IBS and other functional gastrointestinal (GI) disorders.

Several underlying mechanisms are under investigation as possible causes of bloating in IBS (as well causes of IBS in general). It's possible that many of them are inter-related, with one contributing to others, to make up a complex picture of what's happening in your body.

Some possible underlying mechanisms include:

• Disruption of the brain-gut axis: A complex interaction between the brain and gut bacteria means psychological stress can impact the balance of bacteria and vice versa.
• Increased intestinal permeability ("leaky gut"): Improper function of the intestinal lining may allow partially digested food and bacteria to leave the digestive system, trigger inflammation, and interfere with the balance of gut bacteria.
• Intestinal immune activation: Low-grade inflammation may be due in part to abnormal activity of the immune system, which causes inflammation as part of the healing process.
• Visceral hypersensitivity: People with this tend to feel bloated when someone else wouldn't. It usually occurs without distension.
• Gastrointestinal dysmotility (impaired movement): This causes gas to get trapped in the first and middle parts of the colon.
• Impaired abdominal wall response to pressure: Found in people with both chronic bloating and distension, the reaction of the diaphragm and abdominal wall muscles to the pressure of gas is the opposite of what it should be.

Evidence also suggests that bloating may especially be a problem for subgroups of IBS patients who have:

• Carbohydrate and other food intolerances: Poor absorption may lead to fermentation, which increases gas production.
• Small intestine bacterial overgrowth (SIBO): Excess levels of some bacteria may be responsible for the fermentation of carbohydrates.
• Bacterial imbalances: Some healthy bacteria in the digestive tract may be reduced, which can slow digestion.

In people with IBS-C, the longer it takes for digested material to travel through the colon, the more likely it is that they have bloating and distension.

IBS Symptom Relief

Bloating is a notoriously difficult symptom to treat. However, you do have several options to explore to get rid of bloating. IBS is different for everyone, so expect to do a lot of experimentation before you find what works best for you, and try not to get frustrated when your experience doesn't match that of other people with this condition.

IBS Medications

No treatments are definitively proven to improve bloating in IBS. Common drugs that doctors may recommend include:

• Prokinetic agents to increase bowel motility, including Motilium (domperidone) and Reglan (metoclopramide)
• Antispasmodic drugs, including Menoctyl (otilonium) and Bentyl (dicyclomine), to calm spasms in the intestinal walls that can trap gas (IBS used to be called "spastic colon")
• Antidepressants to help correct the brain-gut dysfunction, including tricyclics (TCAs) and selective-serotonin reuptake inhibitors (SSRIs)
• Prosecretory drugs, a kind of prescription laxative, including Linzess (linaclotide) and Trulance (plecantide)
• Viberzi/Truberzi (eluxadoline), which alters the activity of certain cell receptors in the nervous system and improves symptoms of IBS-D
• Serotonergic agents such as Lotronex (alosetron), as the hormone/neurotransmitter serotonin is involved in digestive motility, sensation, and secretion
• Antibiotics, which may be helpful for those with SIBO, including Xifaxan (rifaximin) and Biaxin (clarithromycin)
• Bulk laxatives, available over-the-counter (OTC), to help you expel gas and feces
• Gax-X (simethicone), an OTC medication that can help you eliminate gas

Other IBS Treatments

While medications may help, they may not alleviate all of your symptoms. Many people with IBS include other types of treatments in their regimen, including:

• Dietary changes, especially a low-FODMAP diet or elimination of "trigger" foods
• Probiotic or prebiotic supplements, which may help balance gut bacteria
• Peppermint oil, which is a natural antispasmotic (see warning below)
• Psychological therapies including cognitive behavioral therapy, relaxation therapy, and hypnotherapy
• Exercise and physical fitness, which studies show may help ease symptoms

While they've received less scientific attention than other types of treatments, some evidence supports the use of mind-body treatments for IBS.