Health, Why is our gut our second brain?

Have "fear on the stomach" or "knotted stomach", "digest information", "take guts" ... Expressions of everyday life that speak volumes about the importance of our digestive system ... And who takes a whole new dimension in light of new scientific discoveries that elevate the gut and its microbiota to the rank of the second brain! Back on the advent of an organ unloved, which must be cared for.

Summary

1. The importance of the intestinal microbiota
2. The 200 million neurons of the digestive tract
3. The intestine, seat of our emotions
4. The intestine, a new research track for Parkinson's disease

USA, 1999. Professor Michael Gershon, neuro-gastroenterologist at Columbia University (New York) for the first time qualifies the gut as a "second brain". Pioneering work that highlights the importance of the gut-brain axis.

The importance of the intestinal microbiota

Our organization hosts a large number of bacterial species. These communities of microorganisms, called "microbiota" elect domicile in different places of our body: the mouth, the skin, the vagina ... But especially the intestine! This organ, which measures approximately 8 meters long, is home to up to 100,000 billion bacteria, mainly located in the small intestine and especially the colon. Scientists estimate that nearly 90% of feces are ... bacteria! These bacteria, associated with other microorganisms such as viruses and yeasts, form the "intestinal flora" now renamed "intestinal microbiota" by the scientific community.

In utero, the digestive tract of the fetus remains a sterile medium. At birth, breastfeeding, dietary diversification ... the gut microbiota of an individual is formed over the years, to contain nearly 1000 different bacterial species in a healthy adult. A bacterial world that weighs nearly 2 kilograms and that specialists increasingly apprehend as an organ in its own right, just like the heart, the lung or even the brain! Because, beyond its role in digestion, the microbiota plays a major role in metabolic, immune and neurological functions.

The 200 million neurons of the digestive tract

Experts estimate that nearly 200 million neurons line our digestive tract. The same neurons as those lodged in our brain! "It is a true autonomic nervous system that is set up during embryogenesis," recounts Francisca Joly Gomez, gastroenterologist, professor of nutrition at the University Paris-Diderot and author of the book Gut, our second brain.

Ensuring intestinal motility is the first function of this nervous system called "enteric". "It allows the intestine to contract, especially to advance the bolus," says Francisca Joly Gomez. "What organization would be such a network of nerves to handle a common pipe smoker?" Asks the German doctoral student Giulia Enders humorously in his best-selling book The discreet charm of the intestine. Indeed, 80% of these nerve cells are actually responsible for transmitting information from our intestines into our brain.

Our digestive tract thus remains in permanent interaction with our central nervous system, ie the brain. How? Through hormonal secretions. "As the brain, the neurons of the gut are able to produce hormones and neurotransmitters, such as dopamine or serotonin," says Francisca Joly Gomez. Thus, the neurons that line our digestive tract produce as much dopamine as the brain and secrete up to 95% of the serotonin present in the body. Two hormones that we know are so indispensable to our psychic health!

The intestine, seat of our emotions

Yes, our emotions are also lodged in our gut. Have "fear on the stomach" or "knotted stomach", "digest information", "take guts" ... These expressions of everyday life have a scientific explanation. In situations of stress or anxiety, our brain will send messages to our gut. Consequences: the latter will contract, causing spasm and altering the intestinal transit ... In times of stress or depression, the digestive system will also produce more ghrelin, a hormone that controls appetite and fat loss ... Psychic health, digestive and metabolic ... Everything is intimately linked! "The role of the gut microbiota in psychic diseases (depression, anxiety-depressive syndrome) or eating disorders (anorexia nervosa, bulimia) are thus new areas of research," recounts Francisca Joly Gomez.

The intestine, a new research track for Parkinson's disease

According to recent studies, neurodegenerative diseases may also be born in the gut. Researchers are particularly interested in Parkinson's disease, which attacks neurons. "In people with Parkinson's disease, we find that the neurons of the gut present the same abnormalities that are usually found in the brain," says Francisca Joly Gomez. "Moreover, in many patients, digestive disorders such as constipation may precede neurological and motor disorders ... These scientific discoveries suggest the possibility of new medical examinations to diagnose the disease early".

It is certain that our second brain has not finished animating the scientific community!