Frontiers in microbiologyApr 13, 2026

How gut-friendly bacteria may affect mental health: findings from human studies

Gut-Brain Axis Weekly Brief ↗PubMed ↗DOI ↗OA ↗

Updated Apr 14, 2026

Abstract

Probiotics may influence mental health through the gut-brain axis, with varying effects depending on specific strains and individual factors.

Clinical trials have shown both improvements and limitations in mood, anxiety, sleep quality, and cognitive performance from specific probiotic strains.
Effects of psychobiotics are influenced by factors such as dosage, strain specificity, delivery method, and baseline stress levels.
Mechanistic evidence indicates that psychobiotics may affect neuroactive substances and inflammation, potentially impacting cognitive and emotional processes.
Some studies highlight the challenges of applying preclinical findings to clinical settings, especially in populations with low baseline stress.

Simplified

Recent research has highlighted the gut-brain axis as a critical modulator of mental health, positioning probiotics as promising psychobiotic interventions for anxiety, stress, depression, and cognitive function. Clinical trials investigating strains such as, and multi-strain formulations have demonstrated strain- and context-specific effects on psychological and physiological outcomes. While some studies reported improvements in mood, anxiety, sleep quality, and cognitive performance, others showed limited effects, particularly in healthy populations with low baseline stress levels, reflecting the challenges of translating preclinical findings into clinical applications in humans. Mechanistic evidence suggests that psychobiotics may influence neuroactive metabolites, short-chain fatty acids,-aminobutyric acid, serotonin, and anti-inflammatory pathways, thereby modulating cognitive and emotional processes. The effects happen dependent on factors such as dosage, strain specificity, delivery method, baseline stress or symptom levels, and co-administration with conventional treatments. Collectively, these findings underscore the potential of targeted psychobiotics to enhance mental well-being and support stress resilience, while highlighting the need for carefully designed clinical trials to clarify efficacy and mechanisms. Lactobacillus rhamnosus, Bifidobacterium longum, Lactobacillus gasseri γ

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The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The author BS declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision.

PubMed

How gut-friendly bacteria may affect mental health: findings from human studies

Abstract

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Funding

Competing interests

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You found one interesting study. We’ll send the next 7.

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Recent issues from the gut-brain axis brief