Irritable bowel syndrome (IBS) is a digestive disorder that affects about 11% of people in the developed world. But what exactly is it, what is the cause, and how is it treated?
Doctors refer to IBS as a “functional gastrointestinal disorder”. Essentially, people suffer symptoms without there being visible structural changes to their digestive tract. This is what makes IBS different from other digestive diseases.
IBS has four categories based on which symptom is most common. These include diarrhea, constipation, mixed, or unclassified – IBS-D, IBS-C, IBS-M and IBS-U.
IBS risk factors
Most people develop IBS before middle age, and women are about twice as likely to be diagnosed.
While we don’t know what causes IBS, there are a few factors can increase your risk of developing it:
- A family history of IBS
- A recent gastrointestinal infection
- Psychiatric conditions like depression and anxiety
What are the symptoms of IBS?
IBS features a collection of symptoms that occur together, but these are the most common.
- Change in bowel habits: This can be constipation, diarrhea or, in fewer cases, a combination of the two.
- Abdominal pain: Also known as visceral hypersensitivity, this can be sudden and irregular. The pain is usually spread out, can be both sharp and dull, and often appears after eating a meal.
- Bloating and distention: IBS patients often describe feeling increasingly bloated and gassy. This is likely due to problems digesting food. When you don’t fully digest food, it can reach your colon. There, bacteria start to digest it instead, releasing gases. Excessive gas can contribute to flatulence and bloating. In some cases, bloating is caused by excess water being drawn into the colon.
Many people with IBS report a range of other symptoms. These can include:
- Lowered libido
What causes IBS?
Currently, there’s no unifying theory that can explain IBS symptoms. In fact, the general scientific consensus is that there are multiple factors that contribute to IBS.
While the cause remains unknown, we do know that IBS features a dysfunctional relationship between the brain and gut. When the two fail to work together, the intestines may become hypersensitive, causing pain. The smooth muscle controlling contraction of the gastrointestinal tract may not work properly. When this happens, food moves either too quickly, causing diarrhea, or too slowly, causing constipation.
It’s likely that there are different subgroups of IBS patients, with different causes. For some people, the disease may start in the gut. From there, it feeds back to the brain, leading to symptoms like mood change and anxiety. In others, the order may be reversed, with feelings of stress and anxiety causing IBS.
In other patients, there could be an entirely different cause. For example, genetics, disrupted bile acid metabolism, and microbiome imbalance could be at play.
How is IBS treated and managed?
Special diets are one of the mainstays of IBS management. Recently, there has been a lot of focus on low FODMAP diets. FODMAPs (Fermentable Oligosaccharides, Disaccharides, Monosaccharides, And Polyols) are a family of highly fermentable sugars.
Some people can’t fully absorb these sugars, so they end up in the colon undigested. There, your gut bacteria eat the sugars in a process called fermentation. As they ferment the sugar, the bacteria release gas. It’s then absorbed into the bloodstream and released when you exhale. It can be measured on your breath to gauge how much fermentation is happening in your gut.
In most people, fermentation is healthy. However, in patients with IBS, excess gas combined with a sensitive gut can cause discomfort. Studies have shown that avoiding these fermentable sugars can help reduce IBS symptoms.
Probiotics and Prebiotics
Probiotics are beneficial bacteria that colonize your gut and have many potential health benefits. These can come in the form of concentrated supplements or through eating fermented foods, like kefir. Prebiotics are supplements or foods that feed those bacteria. Studies have shown that probiotics can help reduce IBS symptoms.
Doctors choose which medication to use based on the patient’s symptoms. Some researchers recommend things that reduce spasms, including peppermint oil. There is also good evidence that antidepressants can be effective for IBS.
Drugs like loperamide and rifaximin are often used to treat IBS patients with diarrhea. For those with constipation, soluble fibre supplements, laxatives and drugs like lubiprostone and linaclotide are sometimes recommended.