Society of Certified Senior Advisors: Do Bacteria Form Your Personality?

It’s possible that the tiny animals in your intestines have a lot more influence over you than you ever imagined.

Your body has 10 times more bacteria than cells. This microbiome is diverse, containing colonies of 1,000 - 1,200 species of single-celled organisms. It varies from human to human and in the same person over their lifespan. These bacteria help us digest carbohydrates and synthesize vitamins and amino acids. But research over the last decade is uncovering a link between gut bacteria and personality.

An Oxford University study of fecal samples from 655 adults around the world showed correlations between the “big five” personality traits and gut ecology. What could not be determined is whether this was the result of personality influencing the bacteria, bacteria influencing the brain, or a combination of the two.

“Big Five” Personality Traits

This is the list of defined traits used by psychologists and known as the “big five”:

Openness
Conscientiousness
Extroversion
Agreeableness
Neuroticism

Factors Affecting Number and Variety of Intestinal Bacteria

Birth delivery method
Presence of disease
Diet and lifestyle
Use of certain drugs (i.e. antibiotics)
Geographic location of residence
Nationality
Normal physiological changes associated with age

Thanks to the Canadian Society of Intestinal Research for the above list.

Boastful Mice Become Bashful

Work with animals has suggested that bacteria influence personality. "It was found that if you colonize an aggressive mouse with the gut bacteria from a shy mouse, the temperament of the mouse becomes more similar to the individual from whom they received the gut bacterial transplant," says Katerina Johnson, medical doctor and study researcher. "Therefore in terms of personality traits, it is a credible hypothesis that gut microbes may play a causal role."

In addition, the study was the first to show that babies fed breastmilk grew up to have more diverse gut biomes in adulthood than infants who were raised on formula. “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,” according to Johnson. Moreover, there is nascent evidence to suggest vaginal birth gives an infant its mother's microbiome whereas having an infant by C-section transmits more gut bacteria associated with the hospital to the infant.

Johnson’s work confirmed that intestinal bacteria linked to autism demonstrate a correlation with sociability in neurotypical people. People with autism often have gastrointestinal issues, a link that has engendered extensive prior research.

A previous paper co-authored by Johnson and colleague Professor Kevin Foster, both of the University of Oxford, suggests that sociability, anxiety, stress, and depression may all be affected by the makeup of our bacterial colonies. When stressed mice were given a transplant of certain Lactobacillus species, they become more congenial and their brains produced higher amounts of oxytocin.

Image Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6974692/

Supplements

You may be wondering if you can take a probiotic pill to fight the blues or become more socially engaging. Unfortunately, it’s unknown exactly what role diet may play in the process, which bacteria to use or the effect of underlying health conditions, so the answer at this time is “No.” What you can do on a frequent basis is consume yogurt, which is rich in lactic acid bacteria and has the added benefit of improving bone health.

And increasingly, the medical community is getting behind probiotics that target specific intestinal issues. Different strains of bacteria produce different results. The Clinical Guide to Probiotics by the International Scientific Association for Probiotics and Prebiotics is targeted at practitioners, but with your physician’s approval you can consult it to find the right probiotic for your illness. The free chart, including dosage forms and clinical evidence, is available at AEProbio.

To work, probiotics must remain alive through manufacturing and storage. Supplements are typically superior to probiotics found in food products because of the massive quantity of organisms and stable environment.

It is important to be good to the tiny animals inside you. As their host organism, you should eat a healthy diet to prevent micronutrient deficiencies, common as we get older. And it is not a bad idea to use probiotics to restore balance after treatment with antibiotics.