Breath volatilome analysis reveals new gut microbiome-related metabolites that discriminate high versus low dietary fibre intake.
(2026) Clinical Nutrition — Vol. 61, p. 106662 [1-13] (2026)
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- BACKGROUND & AIMS: Gut bacteria produce a wide variety of metabolites that are playing important roles in human health. Dietary fibres (DF) are beneficial nutrients that have been shown to modulate key intestinal functions when fermented by gut bacteria. Since most bacteria-derived metabolites are volatile, their presence in exhaled breath allows to propose new non-invasive methods to study DF-microbiome interactions in humans. We aimed to identify potential novel biomarkers of gut microbiota activity released in exhaled breath following the consumption of DF at breakfast, upon untargeted analysis in healthy volunteers. METHODS: 14 volunteers (7 women/7 men, 21 ± 2 years old) participated to two test days at a one-month interval, where they received either a low-(2.6 g) or high-(16.1 g) fibre breakfast. Before each test days, stools were collected to evaluate the microbiota composition using Illumina sequencing (V5-V6 region of 16S rRNA gene). Throughout the test days, breath samples were analysed using selected-ion flow-tube mass spectrometry (SIFT-MS). A sparse partial least squares-discriminant analysis (sPLS-DA) identified 30 signals that best discriminated between test days, corresponding to 173 candidate breath compounds. RESULTS: The gut microbiota of the volunteers remained stable one month apart. The composition of exhaled breath shifted starting from 5 h after the high-fibre breakfast ingestion. Ninety compounds were identified as potential metabolites of gut microbes, with 81 showing increased concentrations after the high-fibre breakfast. These included acrylic acid (positively correlated with Faecalibacterium/Ruminococcaceae/Bacillota and negatively correlated with Bifidobacterium/Bifidobacteriaceae/Actinomycetota). The high-fibre breakfast also led to increases in limonene, ethylbenzene/xylene, p-cymene, and methionol that were positively correlated with the genus Faecalibacterium. Moreover, positive correlations were observed between cyclooctane/ethylcyclohexane, methanol and the phylum Bacillota. Dimethyl disulfide was strongly negatively correlated with the genus Bacteroides and its family Bacteroidaceae. CONCLUSION: This study shows that DF consumption at breakfast stimulates the production of exhaled bacteria-derived metabolites reflecting profound changes in the metabolic activity of the gut microbiota. We also identified new potential biomarkers of DF intake, that are not directly linked to DF fermentation. Specific bacteria known to play a role in gut barrier, immunity and host metabolism were associated with those new metabolites.
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Autuori, M., Neyrinck, A., Lengele, L., Viera Olivera, E., Rombaux, M., Rodriguez, J., Cani, P., Walter, J., Bindels, L., & Delzenne, N. (2026). Breath volatilome analysis reveals new gut microbiome-related metabolites that discriminate high versus low dietary fibre intake. Clinical Nutrition, 61, 106662 [1-13]. https://doi.org/10.1016/j.clnu.2026.106662 (Original work published 2026)