Thursday 11 January 2018

Psychobiotics: the state of play

Within clinical PNI, we have known for a long time that our brain and intestines ‘talk’ to one another.  This communication can be positively influenced by psychobiotics. Scientists at Oxford University (UK) explain what this is and provide an overview of the current state of play.


Gut bacteria influence our mood, determine our appetite and control our circadian rhythm.  Probiotic bacteria have a beneficial effect, whilst the absence of these bacteria actually has a negative effect. The presence of pathogenic bacteria can have an adverse effect. The science that influences these interactions in favour of our health is called psychobiotics; probiotics play a role in this.


Stress, immune system and memory

In the last decade it was proven especially in mice that bacteria in the intestines are determining factors for the ability to cope with stress, immune system function and even educational performance and memory. This can be positively affected by probiotics, but are these same results also found in people?


Self-reporting by patients reveals that the use of probiotics can improve the mood. But physiologically there is also evidence of an effect, such as reduced cortisol levels (stress) and fewer inflammations (almost all modern syndromes). Research in mice has revealed that psychobiotics can increase the level of brain-derived neurotrophic factor (BDNF). BDNF is closely involved in learning and memory processes in the brain. This probably works similarly in people.


Gut bacteria important for our biology

"Gut bacteria play a role in very important biological processes, which we then hope to exploit with psychobiotics”, say the scientists. “We’re now on the search for mechanisms, mainly in animal models. The human studies are provocative and exciting, but ultimately most have small sample sizes, so their replicability is difficult to estimate at present. We’re cautiously optimistic.”


But what does the interaction between bacteria, the intestines and the brain actually consist of? The main players are the nervous system of the intestines, the immune system, the vagus nerve and the hormones and neurotransmitters in the intestines, including serotonin and dopamine. What can we do to positively influence this system?


More than just probiotics

Probiotics have shown favourable effects in human research. Nevertheless, probiotics are not the whole answer. "Prebiotics – food for beneficial gut bacteria – are another channel through which we can influence gut bacteria. And we actually want to widen the definition of psychobiotics further still, to also include substances with antidepressant and antipsychotic effects. But food and exercise also have an impact on gut bacteria."


Scientists say that the full potential of psychobiotics for therapeutic practice is still in many ways untapped. However, further research is needed to clarify the mechanisms of action responsible for the effect.



  1. Timothy G. Dinan, Catherine Stanton, and John F. Cryan, Psychobiotics: A Novel Class of Psychotropic, Biological Psychiatry, Volume 74, Issue 10 (November 15, 2013)
  2. Amar Sarkar et al, Psychobiotics and the Manipulation of Bacteria–Gut–Brain Signals, Trends in Neurosciences (2016)