Microflora and its impact on our personality

What does our intestinal microflora impact on? Oh well…the question seems to be rather simple to answer for me – on everything…What does ‘everything’ actually consist of? Is it our brain? For sure! Is it our behaviour? Yes! Is it our personality? It turns out that also that! Research published barely a month ago provides us with more information on this topic. Let’s try to find out more!

Until recently it has been known that the intestinal microflora has a significant impact on physiology and functioning of a human body, not excluding the brain’s functionality of course.Recently, the topic of the influence of intestinal bacteria on human behaviour has been addressed. Our behavior is shaped by the bi-directional flow of information between the brain and the intestines. Probably everyone knows this, but not everyone is aware of it. Peristalsis (that is, natural contractions of the smooth intestinal muscles, resulting in the successive shifting of the intestinal content) largely depends on the stress and emotional state. Each of us has probably experienced diarrhea caused by stress in our life before – this is an example of this dependence. On the other hand, the pain receptors in the abdominal cavity send signals to the brain, thus changing our mood and behavior. This dependence seems to be the more obvious to us. However, one must realise that both the proper functioning of the intestines, peristalsis, as well as the well-being of the gastrointestinal tract, and thus the lack of pain is mainly dependent on the microflora. Since the microflora affects the intestines, the intestines affect our behavior, is there also a direct relationship between intestinal bacteria and human mental health?

Over the last decade, scientific research has quite accurately described the relationships between microflora and anxiety, stress or depression. However, most studies were performed on an animal model, on mice. However, these few human studies have proven the influence of intestinal bacteria on schizophrenia, depression or autism. Furthermore more, it turned out that the adoption of individually selected probiotics reduced the feeling of anxiety amongst people suffering from depression. These results indicate a high therapeutic potential of microflora in relation to mental health.

We already know something about mental health and microflora. Scientists, of course, went further in their reflections. They started research on personality. This is extremely interesting – our personality! How we behave, who we are, how we stand out from the crowd, how we deal with all  life situations … And this depends on the small bacteria inhabiting our intestines ???

Let us first ask ourselves the question “what is personality?”. Researchers from South Korea used the Big Five, a model of personality based on five factors: neuroticism, extraversion, openness to experience, agreeableness and conscientiousness. The unique mix of these factors determines our individual feelings, thoughts and behaviour. Then, the South Korean scientists examined 1.5 thousand stool specimens to determine the microflora. The genetic material of intestinal bacteria was determined, the nutrition and personality of volunteers participating in the study were evaluated. I wonder what were the results of this research…

Well, it turns out that 16 bacterial strains, which affect personality traits, have been identified. In particular, six bacterial strains strongly affect the character of neuroticism and conscientiousness. It was also distinguished that:

• Gammaproteobacteria bacteria have a very significant impact on neuroticism (the more of these bacteria, the stronger the trait);
• Gammaproteobacteria bacteria have a very significant impact on extraversion (the more bacteria these bacteria have, the weaker the quality);
• Lachnospiraceae bacteria have a very significant impact on conscientiousness (the more bacteria there are, the stronger the trait);
• Proteobacteria bacteria have a very significant impact on conscientiousness (the fewer these bacteria, the stronger the trait).

That is quite something… so indeed our personality depends on the intestinal microflora! Therefore one has to realise the important role of bacteria living in our digestive tract! At this point it is worth noting that the microflora’s DNA contains more than 2 million genes – it is more than a human being has in its entire body. So if you think that you are deliberately making decisions, then nothing more wrong! The bacteria living in your intestine have just made that decision!

 

Kim HN, Yun Y, Ryu S, Chang Y, Kwon MJ, Cho J, Shin H, Kim HL. Correlation between gut microbiota and personality in adults: A cross-sectional study. Brain Behav Immun. 2017 Dec 24. pii: S0889-1591(17)30553-6.