Gut microbiotics and emotional response

Research on gut microbiota They have progressed and little by little new clues are being obtained about other possible functions or relationships between what happens at the digestive level and the effect on other body systems. Specifically, there is new research that would relate it to the behavior and emotional response.

It is about all the microorganisms that live installed in the human intestine. These are bacteria that we can consider "Native" or "indigenous" and bacteria "in transit".

The "native" bacteria are those that live permanently in our intestines, but we should not be confused with the term "native" and to think that they have “self-generated” in the intestine, as this cannot happen.

In reality, we are born sterile and our intestines begin to be colonized from the moment of delivery by microorganisms from the mother and the newborn's environmental environment. On the other hand, bacteria "in transit" they temporarily inhabit the lumen or the intestinal mucosa, which they have reached through drinks and food, mainly, and after a while they disappear.

Gut microbiota groups

In 2011, through the MetaHIT project, it was announced that, just as to date it was thought that each individual's was determined by origin (and environment), being like an individual digital signature, actually the composition of the intestinal flora of the people participating in this study converged on three different types of intestinal flora.

You could establish something like that like what happens with blood groups, but in this case, groups of intestinal flora. Three enterotypes were then classified according to the predominant type of microbiota: enterotype A, dominated by bacteria of the Bacteroide type, enterotype B, with a predominance of Prevoleta, and enterotype C, with a dominance of Rominococcus.

Behavior and emotional responses

Last year 2017, an investigation carried out by the University of California-Los Angeles (UCLA), revealed new evidence on the correlation between the composition of the gut microbiota and the emotional response and the behavior.

Previously, animal studies already suggested this relationship. This time, the study has been carried out on 40 healthy women who have been classified into two groups based on their composition. For most of these women (33), the predominant group of bacteria in the intestines was Bacteroides, and for the other 7, Prevotella.

Their brain structure and brain activity have been evaluated by showing them certain images. And it has been observed that women reacted differently to stimuli based on their intestinal bacteria.

Women with more Bacteroides had a thicker layer of gray matter in the frontal cortex and the insula, brain regions involved in the complex processing of information, and they also had a greater volume of gray matter in the hippocampus, involved in the memory process.

In contrast, women with a Prevotella predominance showed less gray matter volume in numerous regions, but a greater number of connections between the brain areas responsible for emotional, sensory and attentional processes. In this second group, they developed less activity in the hippocampus when looking at negative images, and higher levels of anxiety and irritability were measured when viewing the images.

These new data are in line with the conclusions of previous studies that revealed that changes in intestinal bacteria through diet affect brain functions.

In conclusion

These findings confirm the interaction of the brain with the gut microbiota in healthy people. But, despite the results, the researchers warn of the need to interpret them with caution, as they are merely associative and not causal. And it is an incipient area of ​​research on which it is essential to carry out more extensive studies.

On the other hand, it is not known whether, as is popularly said, “it was before the chicken or the egg”, because we do not know if in the face of emotionally unpleasant scenes, it is the bacteria of the intestine that influence the development of the brain structure and its activity or if, on the contrary, it is the pre-existing differences in the brain that influence the type of bacteria that settle in the intestine. Or, what is more, if there is another different element that influences both.

• The digestive system covers digestive functions, but also immune functions and other possible relationships within the body are studied.
• In recent years, three types of gut microbiota depending on the predominant microorganisms in it.
• Different types of gut microbiota have been related to differences at the neurological level, although it remains to be seen what the relationship is.

Bachelor of Food Science and Technology Diploma in Human Nutrition and Dietetics Advance Medical Consultant Nutritionist