Katerina Johnson Publishes New Research Behind “That Gut Feeling”

New research shows that there could be more to “that gut feeling” than we may have first thought. In their recent paper, Pembroke graduate student Katerina Johnson (Interdisciplinary Bioscience (BBSRC DTP) - Experimental Psychology, 2014) and Magdalen College Fellow, Professor Kevin Foster, propose an evolutionary framework to understand why microbes living in the gut affect the brain and behaviour.

Their research was recently published in Nature Reviews Micobiology and suggests that an understanding of the evolution of gut-brain communication may help us to effectively engineer this microbial ecosystem with potential benefits for mental health and well-being.

Research shows that bacteria (especially species belonging to Lactobacillus and Bifidobacterium) can influence social behaviour, anxiety, stress and depressive-like behaviour. Katerina explained:

‘We know there are numerous possible mechanisms, including communication via the vagus nerve (major nerve linking the gut and brain), the immune system and hormonal changes, as well as the production of neuroactive chemicals by gut microbes. But why should we expect gut bacteria to affect behaviour at all?’

One popular theory is that the gut microbiome actively manipulate our behaviour for their own benefit. For example, gut bacteria could make us more sociable to increase their likelihood of transmission to new hosts. In light of evolutionary theory, the authors suggest that this theory is unlikely, given the vast diversity of microbial species and strains inhabiting the gut.

Katerina continued: 'Rather than viewing our microbial companions as puppeteers manipulating our behaviour, instead we suggest that the behavioural effects of gut microbes are more likely a result of natural selection on microbes to grow and compete in the gut, and natural selection on hosts to depend on their microbes. Microbial growth gives rise to metabolic by-products such as short-chain fatty acids known to affect brain function and microbial metabolites can also interact with our immune response.’

'In addition, our physiology may have adapted to make use of our associated microbes. Similar to the ‘hygiene hypothesis’, which posits that an absence of microbes impairs immune system development, we propose that we may have evolved to depend on our microbes for normal brain function, such that a change in our gut microbiome could have effects on behaviour.'

Their full paper titled ‘why does the microbiome affect behaviour?’ can be read here.