Lacy, Brian E. PhD, MD, FACG; Pimentel, Mark MD, FACG; Brenner, Darren M. MD, FACG; Chey, William D. MD, FACG; Keefer, Laurie A. PhD; Long, Millie D. MDMPH, FACG (GRADE Methodologist); Moshiree, Baha MD, MSc, FACG. ACG Clinical Guideline: Management of Irritable Bowel Syndrome . The American Journal of Gastroenterology: January 2021 – Volume 116 – Issue 1 – p 17-44. Rome IV FGIDs: Disorders of Gut-Brain Interaction | ROME IV FGIDs | Chapter 11: Bowel Disorders

Last Updated: 06 August 2022

What Is IBS? A Quick Explainer Guide

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IBS, also known as irritable bowel syndrome, is one of the toughest gut health issues to live with. Whether you're dealing with diarrhea or constipation dominant IBS, or even a mix of both, life can feel like a never ending battle with unpredictable bowel movements. In this short explainer guide, we want to show you what IBS is, including the 4 different subtypes. But just as importantly, we'll walk you through the prevalence data, so you can see just how far reaching IBS is, with almost 10% of the world population suffering from it. Hopefully by the end of this, you'll have a clearer picture of IBS and also know that you are not alone.

Which Foods Really Trigger Your IBS?

Discover exactly which foods you should and shouldn’t eat using our IBS Food Journal.

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.2 However, 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.

Summary

IBS is a chronic and common disorder of gut-brain interaction.
IBS is defined by pain with defecation or a change in bowel habits.
There are 4 subtypes of IBS:
- IBS with constipation (IBS-C)
- IBS with diarrhea (IBS-D)
- IBS with mixed bowel habits (IBS-M)
- IBS with unclassified bowel habits (IBS-U)
IBS subtypes are defined by using diagnostic criteria developed by the Rome Foundation.
Prevalence rates of IBS differ around the world and change based on which Rome criteria is used.
It is estimated that about 9.2% of the world’s population suffers from IBS, with women being more likely to have IBS than men.

Which Foods Really Trigger Your IBS?

Discover exactly which foods you should and shouldn’t eat using our IBS Food Journal.

See All References

Lacy, Brian E. PhD, MD, FACG; Pimentel, Mark MD, FACG; Brenner, Darren M. MD, FACG; Chey, William D. MD, FACG; Keefer, Laurie A. PhD; Long, Millie D. MDMPH, FACG (GRADE Methodologist); Moshiree, Baha MD, MSc, FACG. ACG Clinical Guideline: Management of Irritable Bowel Syndrome. The American Journal of Gastroenterology: January 2021 – Volume 116 – Issue 1 – p 17-44.
Rome IV FGIDs: Disorders of Gut-Brain Interaction | ROME IV FGIDs | Chapter 11: Bowel Disorders

About the Authors

About the Author

Ashley Fuller MS, RDN, CNSC

Biography

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Carolyn Emerson MS, RDN

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Bailey Hanna MS, RDN

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Evidence Based

We are a ‘research-first’ organization, which means all our content is based on the latest scientific evidence, written by our expert dietitians and fact checked by our amazing team.

Here at Digest Life we believe in ‘following the research’. Which means we dive into topics with eyes wide open and simply show you what we find. No pre-existing bias or philosophy sways us.

As you can see all our articles contain extensive references. The numbers used throughout are clickable links to the reference section at end of article. And of course, within the references section itself, you can find direct links to the original source.

Research Methodology

Our panel of experts follows a research methodology built on three core principles:

Strength of Evidence
Transparency
Avoidance of Bias

Strength of Evidence

An evidence hierarchy is followed to ensure conclusions are formed off of the most up-to-date and well-designed studies available. We aim to reference studies conducted within the past five years when possible.

Systematic review or meta-analysis of randomized controlled trials
Randomized controlled trials
Controlled trials without randomization
Case-control (retrospective) and cohort (prospective) studies
A systematic review of descriptive, qualitative, or mixed-method studies
A single descriptive, qualitative, or mixed-method study
Studies without controls, case reports, and case series
Animal research
In vitro research

We interpret the above evidence cautiously with the awareness that the future of gut research will be in n=1 precision interventions.

Given this knowledge, there may be times when systematic reviews or randomized controlled trials miss details that are best captured with study designs that provide a more granular rather than broad perspective.

We present evidence from various study designs in such cases to most accurately portray the state of the evidence.

Transparency

We are transparent in our presentation of information. When referencing studies of weaker design such as case-control studies, in vitro studies, or research conducted in animals, this is clearly stated.

When it is believed that further research is needed to draw conclusions, this is also stated.

We steer clear of cause-and-effect conclusions in cases where the evidence or study design is insufficient to draw a cause-and-effect relationship. When evidence is conflicting, we present all of the available evidence.

Our panel of experts weighs out conflicting information to guide the reader towards the most evidence-supported conclusion. Considerations include the date on which the study was conducted, research methods, and risk of study bias.

Avoidance of Bias

Articles are written and reviewed by a panel of experts with varied personal dietary patterns and beliefs to avoid bias. We prioritize presenting a broad perspective built on facts rather than conjecture.

Overview

Team

Organization

What Is IBS? A Quick Explainer Guide

Which Foods Really Trigger Your IBS?

Table of Contents

What Is IBS?

How Common Is IBS?

Summary

Which Foods Really Trigger Your IBS?

About the Authors

Table of Contents

About the Author

Biography

List of Written Research Articles

About the Author

Biography

List of Written Research Articles

About the Author

Biography

List of Written Research Articles

Evidence Based

Research Methodology

Strength of Evidence

Transparency

Avoidance of Bias

Research

About

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IBS Freedom Roadmap