A groundbreaking study from the University of Vienna has found that individuals with more diverse gut bacteria exhibit stronger hormonal and subjective stress reactivity during acute stress. Published in Neurobiology of Stress, the research challenges conventional views by suggesting that higher microbial diversity may support adaptive, resilient stress responses rather than dampening them.
The study involved 74 healthy adults split into a stress group undergoing the established Trier Social Stress Test (TSST) and a control group performing a neutral task. Researchers collected saliva samples to measure cortisol levels, assessed subjective stress perceptions via questionnaires, and analyzed stool samples for microbiome composition and short-chain fatty acid (SCFA) production capacity.
Key results showed that greater gut microbial alpha diversity correlated with elevated cortisol output and higher perceived stress in the stress group, but not in controls. Notably, microbiomes with higher inferred butyrate production capacity were tied to increased stress reactivity, while propionate production was linked to lower reactivity. Lead researcher Thomas Karner, a psychologist at the University of Vienna, explained: “A robust acute stress response enables flexible adaptation to challenges, and diverse gut bacteria along with certain metabolites appear to facilitate this.”
These findings illuminate the gut-brain axis’s role in stress regulation, with implications for managing anxiety, depression, and related disorders through microbiome modulation via diet, probiotics, or lifestyle changes. While causation remains to be proven in larger trials, the study underscores how gut health could optimize everyday stress resilience.
