What Is IBS?
Technically speaking, IBS is a disorder of gut-brain interaction.1
This means that IBS symptoms likely come about due to altered functioning between the gut and brain. Despite what some may think, IBS is definitely not “all in your head,” because we don’t have much conscious control over the workings between the gut and brain.
To start, a foundational piece of information to understand about IBS is that it’s a disorder diagnosed based on symptoms, not any sort of physical exam or test. The symptom criteria used to diagnose IBS comes from an organization called the Rome Foundation. They’ve updated the criteria throughout the years, with the most recent version being Rome IV, published in 2016.
We cover the diagnostic criteria in great detail in our guide on diagnosing IBS, but in brief, required symptoms include recurrent abdominal pain associated with defecation or a change in bowel pattern. 2However, people also commonly experience other symptoms such as abdominal bloating and distention.2
In order to better understand and target treatment for IBS, the Rome IV criteria also includes IBS subtype criteria based on predominant bowel symptoms. They include:
- IBS with constipation (IBS-C)
- IBS with diarrhea (IBS-D)
- IBS with mixed bowel habits (IBS-M)
- IBS with unclassified bowel habits (IBS-U)
How Common Is IBS?
It’s important to know that if you’re struggling with IBS, you’re not alone. To set the stage for how enormous and challenging of a problem IBS is for so many people, let’s talk about IBS prevalence data.
We’ll warn you ahead of time that there is some variation in the prevalence data and statistics depending on which version of the Rome criteria was used in a given study. This happens for several reasons.
One of those reasons is that when updates are made, the criteria can be more strict or less ‘strict,’ which may increase or decrease the number of people that meet the criteria for IBS. Differences in prevalence data are also due to the varying number of studies available from each version of the criteria.
Because of this, in the graphic below, we use data from the Rome III criteria rather than the Rome IV, as there are not as many prevalence studies available yet where the Rome IV is used.