Breath as a marker of gut microbiome health

lab animal Research highlights Gut microbiome https://doi.org/10.1038/s41684-026-01705-w Breath as a marker of gut microbiome health Check for updates Exhaled breath contains a rich array of volatile organic compounds (VOCs) that are produced by the host and its associated microbes. In a new study published in Cell Metabolism, researchers correlated breath VOC profile to gut microbiome composition in humans and mice. Given that gut microbiome alterations have been linked to a range of diseases, identifying specific gut microbe-derived VOCs in the breath could offer rapid, non-invasive diagnostics for assessing gut microbiota health. The investigators first collected paired breath and stool samples from 27 healthy children and profiled gut microbiome using whole metagenomic sequencing, while they analyzed breath VOCs using gas chromatography-mass spectrometry. Their Lab Animal | Volume 55 | March 2026 | 71 analyses revealed a correlation between gut microbiome composition and VOC profile, with several bacteria showing associations with common breath VOCs. Next, the researchers used controlled mouse models to investigate the effect of the gut microbiome on murine breath. They colonized germ-free mice with cecal contents from conventionally raised mice from two different vendors with distinct microbiota and collected breath and fecal samples one week later. The analyses confirmed that differences in microbiota compositions were reflected in the breath VOC profiles of the “conventionalized” mice. Finally, to directly test whether specific VOCs are produced by gut microbes, the team colonized gnotobiotic mice with one of five common commensals. After two weeks, the researchers collected breath samples from the mice. They found that the breath of mice colonized with a given bacterial species contained VOCs that were also produced by that same bacterium when grown in pure culture. Altogether these results suggest that gut microbiota directly influence exhaled VOCs and that gnotobiotic mice are powerful experimental models for identifying and validating breath biomarkers that reflect the gut microbiota. Alexandra Le Bras Original reference: Hernandez-Leyva, A.J. et al. Cell Metab. https://doi.org/10.1016/j.cmet.2025.12.013 (2026) 71  (...truncated)