New Study Links Babies' Gut Bacteria to Temperament 

A new study from the University of Turku in Finland has found a link between gut bacteria in 10-week-old babies and their behavioral temperament at six months. 


While the research, published in Brain, Behavior and Immunity, does not imply causation it adds to a growing body of evidence connecting gut bacteria and baby food flavors with mood and behavior.

During the study researchers recruited 303 infants and took a stool sample at the age of 10 weeks. At around six months of age the mothers completed a behavior questionnaire evaluating the baby’s temperament. The most general finding was that greater microbial diversity equated with less fear reactivity and lower negative emotionality. 

"It was interesting that, for example, the Bifidobacterium genus including several lactic acid bacteria was associated with higher positive emotions in infants," says Anna Aatsinki, one of the lead authors on the study. "Positive emotionality is the tendency to experience and express happiness and delight, and it can also be a sign of an extrovert personality later in life."

New Study Links Babies' Gut Bacteria to Temperament 

The study found several specific associations between certain bacterial genera and infant temperaments. High abundance of Bifidobacterium and Streptococcus, and low levels of Atopobium, were associated with positive emotionality. Negative emotionality was associated with Erwinia, Rothia and Serratia bacteria. Fear reactivity in particular was found to be specifically associated with an increased abundance of Peptinophilus and Atopobium bacteria.

However, the researchers insist that these findings are merely associational observations and no causal connection is suggested. 

"Although we discovered connections between diversity and temperament traits, it is not certain whether early microbial diversity affects disease risk later in life," says Aatsinki. "It is also unclear what are the exact mechanisms behind the association. This is why we need follow-up studies as well as a closer examination of metabolites produced by the microbes."

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