- Scientists find that your breath may indicate underlying health conditions.
- In a recent study, researchers found that compounds in breath mirror your gut microbiome.
- In the future, this test may even be used to diagnose asthma.
What if a simple exhale could determine that your gut microbiome is out of whack? A growing body of research suggests that natural compounds in your breath may help signal to doctors whether you’re dealing with a serious underlying health condition.
That includes a new study published in the journal Cell Metabolism. For the study, researchers conducted separate experiments with mice and a group of 27 children to measure the levels of molecules that are in their exhaled breath. They then compared the molecules in those breath samples with those found in stool samples to see if there was a link between the two. They did the same with the mice.
After analyzing the data, the researchers discovered that breath contains volatile organic compounds (VOCs) from gut microbes, which may give scientists a clue to what’s going on with someone’s gut microbiome, metabolism, and, ultimately, their health. The researchers even found that exhaled breath may detect an abundance of Eubacterium siraeum, which is a type of gut bacteria that’s a biomarker for asthma in kids.
Meet the experts: Audrey R. Odom John, M.D., Ph.D., division chief of infectious diseases at The Children’s Hospital of Philadelphia; Amesh A. Adalja, M.D., an infectious disease expert and senior scholar at the Johns Hopkins Center for Health Security; Aditya Sreenivasan, M.D., gastroenterologist at Northwell’s Lenox Hill Hospital
Here’s why using breath to make a diagnosis is a growing area of research, plus what your breath signals about your own health.
What might your breath say about your health?
“The compounds in your breath contain important information about your health, and some of those compounds come from the microbes in your gut,” says Audrey R. Odom John, M.D., Ph.D., division chief of infectious diseases at The Children’s Hospital of Philadelphia. There are two different ways your breath may indicate that something is up:
Odor
Using breath for actual diagnostic tests is an ongoing area of medicine. But doctors will sometimes ask for a whiff of your breath during an evaluation to see if they should pursue testing for certain health conditions, Dr. John says. Those may include:
- Type 1 and type 2 diabetes. “Breath has been used historically to diagnose conditions like diabetes because of characteristic ketones in the breath,” Dr. John says. (Ketones are chemicals produced by the liver when the body breaks down fat, and can cause a fruity- or acetone-smelling breath.)
- Liver disease. Known as fetor hepaticus or “breath of the dead,” this distinct breath causes a musty odor that signals severe liver disease or failure, Dr. John says.
- Dry mouth. Dry mouth (a.k.a, xerostomia) is a condition that’s caused by a lack of saliva in the mouth. That unfortunately keeps the mouth from washing away bacteria and food debris, leading to breath that smells like rotten eggs.
Bacteria and viruses
But a doctor taking a whiff of your breath in their office is different from an actual diagnostic test that can tell if you have a health condition. “There are only a couple of breath-based diagnostic tests that are clinically used,” Dr. John says. One is a test for Helicobacter pylori infection, which can cause stomach ulcers. “There is also a COVID-19 breath test that received emergency authorization from the FDA,” she says. The COVID breath test, known as InspectIR COVID-19 Breathalyzer, looks for five VOCs linked with the virus and can give results within three minutes—much faster than the more common nasal swabs.
Why might breath tests be helpful?
Breath testing may signal to doctors to explore a particular diagnosis and make it easier to diagnose other conditions. “Clinicians may soon be able to tell when your gut is healthy based on breath testing alone, which is much more convenient and faster than genetic sequencing of stool,” Dr. John says.
These tests are often quick, easy, and painless, too. “The value is that a non-invasive test can offer a lot of information by sampling the molecules in a person’s breath,” says Amesh A. Adalja, M.D., an infectious disease expert and senior scholar at the Johns Hopkins Center for Health Security. “These molecules can result from an underlying disease process and/or the interaction of human physiology with a microorganism,” he adds. Not only that, Dr. Adalja says that the tests “can be very rapid,” often delivering results as quickly as an alcohol breathalyzer test.
“Breath testing has been clinically validated in very few uses,” says Aditya Sreenivasan, M.D., gastroenterologist at Northwell’s Lenox Hill Hospital. “It is a largely studied area due to it’s non-invasive nature and because it may provide insight into the gut microbiome, which is a relatively new area of research that may revolutionize healthcare.”
Still, Dr. Sreenivasan stresses that this is a work in progress. “Right now, applying these experimental results to clinical practice can be tricky given lack of evidence on how to interpret results,” she says.
What this means for future testing
As a result of the study, the researchers say that compounds in the breath may be able to inform the development of non-invasive tests to learn more about a person’s gut microbiome and make accurate diagnoses. While some breath tests already exist, Dr. John and other researchers are looking to expand this area of medicine.
“I can imagine that breath testing will be used in the future to diagnose a number of diseases, and to give additional information about the health of the body, including metabolic diseases such as diabetes, liver, and kidney disease, and gut health,” she says. “This work is an important step to realize this dream, as understanding where individual breath components come from is key to understanding what they are telling us about the body.”
When to talk to a doctor about your breath
If you’re concerned about bad breath that won’t go away, it’s a good idea to check in with a healthcare provider. Dr. Sreenivasan recommends seeing your doctor soon if there is a sudden change in your breath’s odor, especially if there is no obvious dental issue.
“It can be a sign of a wide range of things,” she says. “From an H pylori infection, sinus issues, acid reflux, slow gastric emptying, diabetes, gastric cancer, bacterial overgrowth, or esophageal diverticulum, further testing can be done by your GI doctor to help determine if there is a serious issue.”
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