Fiber2026-10

Distinction of meal quality and interaction with the gut microbiota by breath volatilome analysis in humans.

Autuori Manon, Lengelé Laetitia, Rombaux Marie, Dormal Valérie et al. — Gut microbes

Summary

This study investigated how the quality of meals influences the compounds we exhale in our breath. Researchers found that certain breath compounds changed after eating balanced or unbalanced meals, and these changes were linked to specific types of gut bacteria. This suggests that analyzing our breath could offer a simple, non-invasive way to monitor our diet and the activity of our gut microbes.

AI-generated summary — read the original

Key points

The types of compounds we breathe out can change depending on the meals we eat.
These changes in breath compounds may indicate the quality of our diet.
Specific breath compounds were found to correlate with the composition of gut bacteria.
Breath analysis could offer a non-invasive method to monitor diet and gut microbe interactions.

What the study looked at

What question the study asked: This research explored whether the quality of meals and the intake of a fermentable substance like lactulose could alter the volatile compounds present in human breath. It also investigated if these breath changes were linked to the composition of an individual's gut microbiota. How it was studied (design/participants): Twenty healthy young adults, equally split between men and women, participated in the study. They completed three separate test days. One day involved consuming lactulose, a sugar fermented by gut bacteria, while the other two days involved eating either a balanced or an unbalanced breakfast and lunch in a crossover design. Throughout these days, breath samples were collected at multiple intervals and analyzed using advanced mass spectrometry. Fecal samples were also taken to identify the types of bacteria in their gut. What it found: The study observed that several breath compounds changed predictably after meals, with some decreasing and others increasing depending on the food consumed. Crucially, certain exhaled compounds, such as acetic acid and methanol, were found to correlate with the presence of specific gut bacteria. These findings suggest that analyzing breath could serve as a non-invasive method to monitor dietary intake, assess meal quality, and understand the complex interactions between our diet and gut microbes.

Dietary takeaway

This study suggests that the compounds we exhale might offer clues about our diet and the activity of our gut bacteria, especially those that ferment dietary components like fiber. While more research is needed, choosing a variety of fiber-rich foods, such as fruits, vegetables, and whole grains, can help nourish a diverse gut microbiota. A healthy gut microbiome produces many beneficial compounds, and this research hints that these could potentially be reflected in our breath. Remember, this is just one study, and dietary advice should always be based on a broader body of evidence.

Abstract

Diet strongly influences the composition and metabolic activity of the gut microbiota, which in turn impacts host physiology and health. The metabolites produced by gut microbes include volatile compounds detectable in exhaled breath, which offers a window to investigate microbial-host interactions. The aim of this study was to explore the influence of balanced and unbalanced meals on exhaled breath composition, while using lactulose as a standardized fermentable substrate to probe microbial fermentation, and whether these changes are associated with gut microbiota composition. Twenty healthy volunteers (10 women/10 men; 22 ± 2 y) participated in three test days, each separated by a minimum 7-d washout period: test day 1 consisted in an acute lactulose intake and test days 2 and 3 were crossover test days with either balanced or unbalanced breakfasts and lunches. Fecal samples were collected before each test day for gut microbiota analysis via sequencing of the 16S RNA gene (V5-V6 region). Breath samples were collected at multiple time points during the test days and analyzed by selected-ion flow-tube mass spectrometry (SIFT-MS). Gut microbiota composition remained stable across test days. Exhaled breath responses followed three patterns: (i) compounds with a postprandial decline (hydrogen sulfide, lactic acid, heptanal, 2,3-butanedione, propanoic acid, and valeric acid), (ii) compounds showing meal-dependent increases, that might either reflect food composition (limonene, 1-phenylethanol/2-phenylethanol), microbial activity in the upper gastrointestinal tract (butyric acid/3-hydroxybutanone, ethanol), or microbial activity in the lower gastrointestinal tract (acetic acid, methanol), and (iii) compounds remaining stable over time with only minor variations. Exhaled acetic acid was negatively correlated with fecal , , , , , , and , while exhaled methanol was positively associated with fecal and . Our data support the interest of breath volatilome analysis as a non-invasive approach to monitor nutritional intake, food quality and nutrition-microbiota interactions in humans. Trial registration: Clinical Trial NCT05949411.

View on PubMed →DOI: 10.1080/19490976.2026.2740921