Our intestine, a second brain? You would be surprised to learn how true this famous expression is! The proof with a new study which shows that the composition of our intestinal microbiota influences, no more, no less, our decision-making and our mood.
According to the Foundation for Medical Research (FRM), the intestinal microbiota brings together “trillions of micro-organisms living mainly in the intestines, in symbiosis with the body, that is to say in an association beneficial to everyone. There are as many as there are cells in our body! These are mainly bacteria, but also yeastsyeasts and viruses ». If we already know that this flora, as it is also called, impacts digestive function, it could also have an influence on behavior, certain emotions, and even certain decision-making. A surprising observation made by scientists from the Brain Institute, in France, and the University of Bonn, in Germany.
This is not the first study to explore this association, but most of the research previously carried out has only focused on animals. “Available data suggests that the intestinal ecosystem communicates with the central nervous system through different channels, including the vagus nervevagus nerve. It also uses biochemical signals that trigger the release of neurotransmitters, such as dopaminedopamine and the serotoninserotoninwhich are essential for the proper functioning of the brain »indicates Hilke Plassmann, head of the Cognitive Control – interoception – attention team at the Brain Institute and professor at Insead, in a press release.
Does your microbiota have a sense of justice?
Based on this observation, the researchers wanted to subject 101 men aged between 20 and 60 to behavioral tests, including the “ultimatum game”, which consists of evaluating decision-making and sensitivity to injustice – or to equity – of an individual. The rules of the game are simple: you have to give a sum ofmoneymoney to a participant and ask him to share it – fairly or not – with a second participant. Who can accept or decline the offer depending on whether it seems fair or unfair. In the second case, none of the players receives the reward.
Most important detail, 51 participants consumed probiotics and prebioticsprebioticsused to rebalance the intestinal floraintestinal florafor seven weeks, while 50 participants received a placeboplacebo. Everyone participated in the game during two sessions, at the beginning and after taking the supplements.
Published in the newspaper PNAS Nexusthe results suggest that the composition of the gut microbiota could influence not only decision-making, but also “sensitivity to injustice”.
Eat better to make better decisions?
In detail, the researchers explain that participants who had taken probiotics and prebiotics were more likely to refuse offers considered unequal, after seven weeks of supplementation. An evolution in decision-making and sensitivity to injustice – or fairness – which was not observed in the placebo group. Participants who consumed supplements were also those who experienced the most significant changes in the composition of their diet. microbiotamicrobiota intestinal.
Final observation and not the least, “the researchers also observed (within the supplemented group) a sharp decrease in the levels of tyrosinetyrosine, a precursor of dopamine, after the seven weeks of intervention. For the first time, a causal mechanism is emerging: the composition of the intestinal microbiota could influence social behavior through dopamine precursors – a neurotransmitterneurotransmitter which intervenes in the brain mechanisms of reward »as we can read in the report of this work.
An observation which should give rise to new, more in-depth and more targeted research. “It is too early to say that gut bacteria are capable of making us less rational and more receptive to social considerations. However, these results clarify which biological pathways we should look at. The prospect of modulating the microbiota through diet to positively influence decision-making is very exciting! We must explore this avenue with the greatest care”estimates Hilke Plassmann, main author of this work.
