Gut feelings: Is the microbiome linked to our personality?

Summary: A new study links the microbiome to personality traits and social behaviors. Those with a larger social network tend to have a more diverse gut microbiome.

Source: University of Oxford

Dr Katerina Johnson, who conducted her PhD in the University’s Department of Experimental Psychology, was researching the science of that ‘gut feeling’ – the relationship between the bacteria living in the gut (the gut microbiome) and behavioural traits. In a large human study she found that both gut microbiome composition and diversity were related to differences in personality, including sociability and neuroticism.

She said: “There has been growing research linking the gut microbiome to the brain and behaviour, known as the microbiome-gut-brain axis. Most research has been conducted in animals, whilst studies in humans have focused on the role of the gut microbiome in neuropsychiatric conditions. In contrast, my key interest was to look in the general population to see how variation in the types of bacteria living in the gut may be related to personality.”

Previous studies have linked the gut microbiome to autism (a condition characterised by impaired social behaviour). Dr Johnson’s study found that numerous types of bacteria that had been associated with autism in previous research were also related to differences in sociability in the general population. Katerina explained: “This suggests that the gut microbiome may contribute not only to the extreme behavioural traits seen in autism but also to variation in social behaviour in the general population. However, since this is a cross-sectional study, future research may benefit from directly investigating the potential effect these bacteria may have on behaviour, which may help inform the development of new therapies for autism and depression.”

Another interesting finding related to social behaviour was that people with larger social networks tended to have a more diverse gut microbiome, which is often associated with better gut health and general health. Katerina commented: “This is the first study to find a link between sociability and microbiome diversity in humans and follows on from similar findings in primates which have shown that social interactions can promote gut microbiome diversity. This result suggests the same may also be true in human populations.” Conversely, the study found that people with higher stress or anxiety had a lower microbiome diversity.

This shows a group of people
Another interesting finding related to social behaviour was that people with larger social networks tended to have a more diverse gut microbiome, which is often associated with better gut health and general health. Image is in the public domain.

Various other key and novel findings were also reported in this study. Most notably, adults who had been formula-fed as children had a less diverse microbiome in adulthood. Katerina commented: “This is the first time this has been investigated in adults and the results suggest that infant nutrition may have long-term consequences for gut health.” Diversity was also positively related to international travel, perhaps due to exposure to novel microbes and different diets. More adventurous eaters had a more diverse gut microbiome whilst those on a dairy-free diet had lower diversity. Furthermore, diversity was greater in people with a diet high in natural sources of probiotics (e.g. fermented cheese, sauerkraut, kimchi) and prebiotics (e.g. banana, legumes, whole grains, asparagus, onion, leek), but notably not when taken in supplement form.

“Our modern-day living may provide a perfect storm for dysbiosis of the gut. We lead stressful lives with fewer social interactions and less time spent with nature, our diets are typically deficient in fibre, we inhabit oversanitized environments and are dependent on antibiotic treatments. All these factors can influence the gut microbiome and so may be affecting our behaviour and psychological well-being in currently unknown ways.”

About this neuroscience research article

University of Oxford
Media Contacts:
Katerina Johnson – University of Oxford
Image Source:
The image is in the public domain.

Original Research: Open access
“Gut microbiome composition and diversity are related to human personality traits”. Katerina Johnson.
Human Microbiome Journal doi:10.1016/j.humic.2019.100069.


Gut microbiome composition and diversity are related to human personality traits

The gut microbiome has a measurable impact on the brain, influencing stress, anxiety, depressive symptoms and social behaviour. This microbiome–gut–brain axis may be mediated by various mechanisms including neural, immune and endocrine signalling. To date, the majority of research has been conducted in animal models, while the limited number of human studies has focused on psychiatric conditions. Here the composition and diversity of the gut microbiome is investigated with respect to human personality. Using regression models to control for possible confounding factors, the abundances of specific bacterial genera are shown to be significantly predicted by personality traits. Diversity analyses of the gut microbiome reveal that people with larger social networks tend to have a more diverse microbiome, suggesting that social interactions may shape the microbial community of the human gut. In contrast, anxiety and stress are linked to reduced diversity and an altered microbiome composition. Together, these results add a new dimension to our understanding of personality and reveal that the microbiome–gut–brain axis may also be relevant to behavioural variation in the general population as well as to cases of psychiatric disorders.

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