Your Personality and Your Gut Bacteria: Mirror Reflections?

I posted the news last week on the Biome Buzz’ Facebook page, about research out of Oxford University in the UK[i] which connected personality type to specific microbiome patterns.  The story has gotten huge coverage in the world of the biome, so I reckon I better write about it in greater detail.  After all, you come here to get the latest news in detail, hot off the presses, right?

The study involved fecal samples from 655 adults (71% female, 29% male).  They all filled out a questionnaire which asked about lifestyle, health, behavior, and so forth.  The paper’s author, Katerina Johnson (from the Department of Experimental Psychology), then associated personality type (for example, sociability and neuroticism) to the gut bacteria in the samples.

The questionnaire used, the International Personality Item Pool, uses 50 items to group people into 5 personality types:

  • “extraversion, or the “propensity to seek and enjoy others’ company”
  • agreeableness, defined as “trust and cooperation in social interactions”
  • conscientiousness, or the “attention to detail and focus”
  • neuroticism, i.e., the “tendency to feel negative emotions”
  • openness, which researchers have described as “creativity, intellectual curiosity, and willingness to seek new experiences”[ii]

After adjusting the data for variables that might influence the composition of the bacteria (sex, age, BMI, birth delivery mode, infant feeding method, antibiotic use in the last 6 months, probiotic use), she was left with a pool of 261 qualifying participants.

The results were pretty remarkable:  “…both gut microbiome composition and diversity were found to be related to differences in personality.”

Those types of bacteria now associated with autism spectrum disorders proved consistent in that, in the general population, they were also found in less social people.  Those individuals with extensive social networks had more diverse microbiota, suggesting that social behavior is important for microbiome health. (We are social animals, after all, so this didn’t shock me.)  For example, Akkermansia (whose health benefits I have covered several times before, including here), Lactococcus and Oscillospira were “…found to be more abundant in individuals with a higher sociability score.”  This coincides with prior research which has shown that those with autism have a reduction in Lactococcus and Oscillospira, and 1 study thus far has found lower levels of Akkermansia as well.  In animal studies, Oscillospira has already been associated with social behavior, and both this species and Akkermansia, “…are associated with good health; Akkermansia has anti-inflammatory properties and there is some evidence it may be protective against metabolic disorders while lower levels of Oscillospira are linked to inflammatory disease.”

Also really interesting:  those who were less social behavior had higher levels of Desulfovibrio and Sutterella, the former of which I have covered in relation to autism in the past (see here):  “…in fact, it has been hypothesized that Desulfovibrio species may play an important role in the pathophysiology of autism.”

Another not-surprise: stress and anxiety reduced microbiota diversity.  And, as I have talked about in the past (see here), poor sleep quality also appeared to lead to a loss of diversity.

A few other important points:

  1. People who ate more foods with naturally occurring pro- and prebiotics had significantly lower levels of stress, anxiety and neuroticism, and proved less likely to develop a mental illness:  “Diversity of the gut microbiome was also related to the amount of food people consumed containing natural probiotics and prebiotics.”
  2. Remarkably, the research did not show the same for pro- and prebiotics in supplement form. This latter finding, however, may be because those who have been on antibiotics or who have gut issues – thus already likely having dysbiosis issues – are more likely to use supplements.
  3. This one is not a surprise. Those who were formula fed as babies had less diverse microbiota.

The author points out that the relationship of the gut microbiota and behavior is bidirectional and thus, “…the gut microbiome can affect the stress response and stress also disrupts the gut microbiome.”  We can assume then that improving one’s social behavior may have long-term health benefits.

I want to share Dr. Johnson’s concluding remarks as they are definitely worth your time to read:

“…it is pertinent to reflect on the ways in which 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.”

I couldn’t have said it better myself!


[i] Johnson, KV-A. Gut microbiome composition and diversity are related to human personality traits. Human Microbiome Journal. 2020;15.


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