Exhaled breath can have hundreds of different compounds in it, some of which could have diagnostic potential.Credit: Getty
The chemicals found in a person’s breath might reveal the identity of the microbes in their guts, according to a study published today in Cell Metabolism1.
Using mice and a group of 41 children, Andrew Kau, an immunologist at Washington University in St. Louis, Missouri, and his colleagues measured the levels of molecules in exhaled breath and showed how they could be used to partially predict the identity and abundance of certain gut bacteria, including one species that is associated with asthma.
“The gut-microbiome composition can shape the type of compounds you see in breath,” says Kau. This was suspected, he says, but “it was never certain”.
AI’s keen diagnostic eye
The work might lead to devices for diagnosing infections and help to guide treatment of conditions influenced by gut bacteria. Existing methods that test stool samples are time-consuming and more complicated.
“I love the idea of using breath measurements to get more information about health,” says Katrine Whiteson, a biochemist at the University of California, Irvine. “Breath is an amazing measurement because it’s aggregate information from the lung and the whole body.”
Volatile research
Scientists have long wondered about the possibility of using the chemical metabolites in breath to diagnose disease. Human cells and bacteria produce more than 250,000 molecules, or metabolites, as they grow and survive. Some of these can enter the bloodstream, circulate to the lungs and diffuse into exhaled air.
The work has proven daunting, however, says Kelly Redeker, a chemist at the University of York, UK, who was not involved in the study. “The complexity of the system is massive.”
