Your personality may be related to your gut microbiome

Gut microbiome and personality. Just when you thought there couldn’t possibly be anything else that relates to the human gut microbiome. New evidence suggests that even our personality traits may be shaped by our gut bugs!

This study aimed to explore the potential relationship between gut microbiome composition and diversity and human personality traits. Accordingly, 655 participants submitted their fecal samples to analyze the gut microbiome.

The journal:

Human Microbiome Journal

The paper:

Gut microbiome composition and diversity are related to human personality traits (Mar 2020).

The authors: 

Katerina V.-A. Johnson

Limitations: 

1. Since this is a cross-sectional study, it cannot establish a causal relationship between gut microbiome and personality traits. It is possible that personality traits influence gut microbiome composition and diversity, rather than the other way around.

2. The study only included participants from one geographic region (China), which limits the generalizability of the findings to other populations with different lifestyles, diets, and environments.

3. Factors that could influence gut microbiome composition and diversity, such as medication use, stress, and sleep quality were not controlled for. 

How were the gut microbiome and personality assessed?

The gut microbiome was assessed by analyzing fecal samples collected from the study participants. The researchers used high-throughput DNA sequencing to identify and quantify the bacterial species present in the fecal samples. 

The study used a well-established personality assessment tool called the Big Five Inventory (BFI) to assess participants’ personality traits. The BFI measures five broad dimensions of personality, including extraversion and neuroticism, openness to experience, agreeableness, and conscientiousness.

How are the gut microbiome and personality linked?

Extraversion

The results shows that individuals with higher levels of extraversion tended to have higher gut microbiome diversity. Additionally, higher levels of the genera Faecalibacterium and Dialister  were associated with higher levels of extraversion.

Neuroticism

Neuroticism, on the other hand, is a personality trait characterized by emotional instability, anxiety, and moodiness. People who score high in neuroticism are often described as anxious, worrisome, and easily upset.

Individuals with higher levels of neuroticism had lower gut microbiome diversity, while lower levels of the genus Blautia was associated with higher levels of neuroticism. Conversely, higher levels of Bacteroides was associated with lower levels of neuroticism.

Agreeableness

The study defined agreeableness as a personality trait characterized by a tendency to be cooperative, empathetic, and compassionate towards others. People who score high on the agreeableness dimension of the Big Five Personality Inventory (BFI) are often described as warm, considerate, and helpful, while those who score low are sometimes seen as more competitive, skeptical, or independent-minded.

The study found a significant positive correlation between gut microbiome diversity and agreeableness, which suggests that people who score higher in agreeableness may have a more diverse gut microbiome. 

Openness

Openness is a personality trait characterized by a tendency to be imaginative, curious, and open-minded. People who score high on openness are often described as creative, intellectually curious, and open to new experiences, while those who score low are often seen as more conventional, practical, and focused on routine.

Interestingly, the study did not find any significant correlations between gut microbiome composition or diversity and this personality trait.

Conscientiousness

Conscientiousness is a personality trait characterized by a tendency to be organized, responsible, and goal-oriented. Overall, people who score high on this dimension of the BFI are often described as dependable, hardworking, and detail-oriented, while those who score low are sometimes seen as more impulsive, disorganized, or unreliable.

The study found a significant negative correlation between genus richness (the number of different bacterial genera present in the gut microbiome) and conscientiousness. To clarify, this means that individuals who scored higher on conscientiousness tended to have a less diverse gut microbiome.

However, the relationship between gut microbiome composition and conscientiousness was not statistically significant. This suggests that while there may be a correlation between gut microbiome diversity and conscientiousness, more research is needed to determine the nature of this relationship and whether it is causal in nature.

Possible explanations for how the gut microbiome and personality are related:

The author suggested that gut bacteria may be involved in the production of neurotransmitters such as serotonin and dopamine, which are known to play a role in regulating mood and behavior.

Since the gut microbiome has been linked to various physiological processes, including immune function, inflammation, and metabolism, this could in turn impact brain function and behavior. In addition,it was suggested that the gut microbiome could be influenced by environmental factors such as diet and stress, which are linked to personality and behavior.

To summarise the gut microbiome and personality links:

• Gut microbiome composition and diversity are related to human personality traits.
• Higher levels of the genus Faecalibacterium are associated with higher levels of extraversion.
• Lower levels of the genus Blautia are associated with higher levels of neuroticism.
• Higher levels of the genus Bacteroides are associated with lower levels of neuroticism.
• Higher levels of the genus Dialister are associated with higher levels of openness.
• There is a significant negative correlation between genus richness and conscientiousness, meaning individuals who score higher on conscientiousness tend to have a less diverse gut microbiome.
• The relationship between gut microbiome composition and openness was not statistically significant.
•  These associations between gut microbiome and personality were independent of age, sex, body mass index (BMI), and diet.

Evidently, the study suggests that there may be a complex relationship between gut microbiome composition and personality traits. However, more research is needed to fully understand this relationship and its implications for human health and well-being.