Can a Breath Test Detect Irritable Bowel Syndrome?

Irritable bowel syndrome (IBS) is a common disorder that affects the digestive system. It impacts at least 10 to 15 percent of adults in the United States. People living with IBS often have bothersome and painful symptoms. These symptoms may include stomach pain, gas, bloating, diarrhea, and constipation.^1,2

There is no conclusive test to diagnose IBS. To reach an IBS diagnosis, doctors:^3,4

• Look at your medical history
• Rule out other conditions
• Use guidelines called the Rome IV criteria to assess your symptoms

This is an imperfect system, and many people go undiagnosed. But promising new research could change that.^3,4

Scientists have found that a breath test could help identify IBS. This noninvasive tool could help improve diagnosis and lead to more effective treatment options.^3,4

What is the gut microbiome, and why does it matter?

Trillions of organisms like bacteria and viruses live in the digestive tract (gut). That network of organisms is called the gut microbiome. Some of these organisms produce gas, and gas levels can be measured on a breath test. So, a breath test may be able to help doctors understand what is going on in your unique gut microbiome.^3,5

The main cause or reason for IBS is not well understood. But research continues to show that the gut microbiome plays a role.³

People with different IBS subtypes have different gut microbiomes

People living with IBS often have different symptoms, which are grouped into IBS subtypes. These subtypes are considered to be on a continuum. Your subtype can change over time. IBS subtypes include:^2,3

• IBS-C – Primary symptom is constipation
• IBS-D – Primary symptom is diarrhea
• IBS-M – Both constipation and diarrhea are present

In a 2022 study, researchers used breath tests to show that people with different IBS subtypes have different gut microbiomes. People with IBS-C and IBS-D had different bacteria and gas-producing organisms in their digestive tracts.^3,6

Using the breath test results, researchers created microbiome profiles for IBS-C and IBS-D:^3,6

• IBS-C is linked with higher levels of methane and methane-producing bacteria. People living with IBS-C had more diversity in their gut bacteria.
• IBS-D is linked with higher levels of hydrogen, hydrogen sulfide, and hydrogen sulfide-producing bacteria. People living with IBS-D had less diversity in their gut bacteria.

The researchers found that specific organisms in the gut are related to each subtype. In IBS-C, the main methane-producing organism was Methanobrevibacter smithii. In IBS-D, the main hydrogen sulfide-producing bacteria were Fusobacterium and Desulfovibrio.^3,6

How will this research affect people living with IBS?

Understanding how the gut microbiome differs between IBS subtypes could help in many ways. It could lead to more accurate testing and better treatment options for IBS. It could help scientists develop drugs and custom therapies. It could help doctors create more effective nutritional guidance for people living with IBS-C and IBS-D.³

IBS is common, but less than 10 percent of adults receive a diagnosis. A breath test is a simple and noninvasive tool that doctors are familiar with. A standard IBS breath test could help researchers better understand IBS and develop treatments that work.^3,4,7