The power of psychobiotics on the Gut-Brain axis
Psychobiotic is a term used in preliminary research to refer to live bacteria that, when ingested in appropriate amounts, might confer a mental health benefit by affecting the microbiota of the host organism. That is to say probiotics with benefits on mental health, including probiotics with a positive impact on stress, anxiety-like, depressive-like symptoms, and sleep.
Psychobiotics might help with mental disorders
Several studies and meta-analysis have highlighted the significant impact of the gut microbiota on mental health, emphasizing the bidirectional communication between the gut and the brain. Outcomes showed the beneficial effects of psychobiotics for mood, anxiety, depression, and early-life stress. In 2019, a meta-analysis looked at 27 probiotic or symbiotic interventions and showed a significant improvement in depression and anxiety [Liu 2019]. Moreover, a recent systematic review identified 42 clinical studies investigating the effects of psychobiotics on the gut-brain axis. Among these studies, major depressive disorder (MDD) was the most frequently studied condition, with 17 studies focusing on MDD [Ribera 2024]. It is important to note that the benefits are not homogeneous for all the probiotics tested, but are strain-dependent, which is the case for most of the beneficial effects of probiotics.
What is the current state of research on probiotics in the Gut-Brain axis?
According to the World Health Organization (WHO), stress is a common health issue across the globe. From day-to-day stresses to financial pressures, lifestyle changes, environmental influences, people are living with more pressures than ever. Given that stress is a risk factor and a consequence of many modern diseases, the clinical research on mental health is diversify. This diversity necessitates studies involving a wide range of participants, including healthy individuals as well as people suffering from depression, chronic diseases, neurodegenerative diseases, and the elderly.
Face to global population need, the gut-brain axis is a rapidly advancing field of research, with probiotics playing a pivotal role in understanding and potentially modulating this complex interaction. Psychobiotics have shown promise results to support mental health and related effects. But, despite the promising results, challenges remain in optimizing trial designs and understanding the specific mechanisms of action. These challenges were highlighted in a recent review which pointed out the importance to study probiotics at the strain level and concluded that further research is needed to fully understand therapeutic potential of psychobioitcs in managing mental disorders [Binda et al. 2024].
These challenges were also prominently discussed at the fifth edition of the Mind, Mood & Microbes event, an international conference dedicated to microbiota-gut-brain axis which gather leading scientists, healthcare professionals, and industry partners. As research progresses, the collaborative efforts in this space continue to drive innovation, redefining our approach to mental health by considering the gut as a key player. The future of health relies on personalized interventions that recognize the individuality of each person, tailoring treatments to meet unique needs and leveraging the gut-brain connection for holistic mental health care.
On-going clinical studies on psychobiotics
From 2020 to March 2025, 230 clinical trials targeting the gut-brain axis with probiotics were registered.
Currently, the most frequent areas studied are depression, neurodegenerative diseases, such as ALS, Alzheimer or Parkinson’s diseases, but also cognition & neurodevelopment. Other areas include more commonly stress & anxiety and sleep, but also more specific disorder including autism, ADHD, Migraine, Epilepsy and Schizophrenia. The techniques associated with these studies are also evolving. Researchers use professionally validated questionnaires and biomarkers such as cortisol, as well as brain imaging, which reveals the regions of the brain being stimulated and what this means. Research teams are also exploring ways to study the brain without using invasive techniques. We estimate that at least 30% of ongoing research is funded by private companies. This shows that both academia and private industry are investing in this research and working collaboratively.
