We are clear that our intestine it is not sterile and is full of microorganisms that can help or harm our health depending on their quantity and quality. Together they form what is known as gut microbiota.
The influence of his state extends beyond the gastrointestinal systemsince its balance is related to diseases such as obesitythe type 2 diabetesthe celiacthe Crohn’s disease and the depression. In addition, the intestinal microbiota is considered our second brain as it has been seen how it is strongly correlated with our emotions.
How the brain and gut are related
The relationship between the intestines and the brain is so clear that there is even a specific scientific branch for its study. The neurogastroenterology It is an area of research in the field of gastroenterology that refers to the interactions of the central nervous system (CNS), that is, the brain, and the intestine; this connection is called “gut-brain axis”.
The gut-brain axis is a two-way communication system and includes the CNS and the enteric nervous system (ENS) –of the intestines–, which involves nerves, hormones and other molecules called neuropeptides and cytokines.
The intestines have several villi made up of different cells, among which are the enteroendocrine. These enteroendocrine cells communicate through hormones and specific nerves that react to mechanical, thermal and chemical stimuli, and generate electrical impulses that give rise to this communication between brain and gut.
With the gut microbiota care the symptoms of certain mental health conditions and situations can be regulated, since it is possible to intervene in this gut-brain axis. Studies in humans have indicated how alteration of the gastrointestinal microbiota modulates reactivity to stress and is linked to worse outcomes in mental health clinical cases.
Much of this evidence comes from studies of fecal microbiota transplant: just as it sounds, they take feces from one person and pass it through the intestines of another person or organism to transfer certain microorganisms and thus modify the gut microbiota.
An example of a mechanism of interaction between the brain and the intestines are the metabolites of tryptophan (substances produced through the metabolism of this essential amino acid).
He tryptophan can become serotonina neurotransmitter that regulates mood and is known as the “happiness hormone”, or in kynurenine, a metabolite that in high amounts initiates inflammation processes and contributes to depressive states due to the lower production of serotonin. He stress caused by infections and psychological stress are key factors that determine the production of one or another metabolite.
Inflammation and microbiota
The intestinal microbiota can stimulate the systemic inflammation (general inflammation of the body); several studies have shown that specific pro-inflammatory markers occur at higher levels in people with depression.
The cause of the increased intestinal inflammation is unknown.However, there is a hypothesis that this inflammation is due to leaky gut.
He leaky gut, as its name suggests, is characterized by an increase in intestinal permeability, which decreases the function of the intestinal barrier. This barrier prevents microbes and other inflammatory agents from moving through the epithelium (one of the layers of the intestine); different species of bacteria have the ability to
strengthen or weaken this barrier.
When this barrier is damaged it can cause a intestinal permeability which allows microbial products to activate the inflammatory immune response. Inflammation that occurs as a result of leaky gut is thought to influence brain function through inflammatory markers that cross the blood-brain barrier (the barrier that separates the CNS from the rest of the body), affecting central nervous system function. , such as serotonin signals, and contributes to symptoms of depression.
What can we do to improve the microbiota and, therefore, emotions?
The intestinal microbiota can be modified through what we eat and do. Lead a healthy lifestyle it can help improve the quality of our intestinal microbiota so that it acts in our favor and does not cause the inflammation that we mentioned that can alter our emotions.
Consumption of probiotics can help improve the intestinal microbiota, but it is important to know that it is always in constant change, according to our habits, and that probiotics are live bacteria they eat what we eat too, so having bad habits and taking probiotics makes no sense: the good bacteria that we are introducing into our body cannot survive if we do not feed them healthy foods.
The foods that can positively impact our intestinal microbiota are those that contain fiberLike all whole plant-based foods (vegetables, fruits, whole grains, legumes, seeds, nuts, etc.) and fermented foods As the sauerkrauthe tempehthe kombucha or the misoamong others.
So try to include this type of food in your day to have a healthy microbiota and keep you in a good mood.
Bibliography:
–Chahwan B, et al. Gut feelings: A randomized, triple-blind, placebo-controlled trial of probiotics for depressive symptoms. Affect Disorder. 2019;253:317-326.
–Clair R. Martin, Vadim Osadchiy, Amir Kalani, Emeran A. Mayer. The Brain-Gut-Microbiome Axis. Cell Mol Gastroenterol Hepatol. 2018; 6(2): 133–148.
–Sarkar A, Harty S, Lehto SM, Moeller AH, Dinan TG, Dunbar RIM, Cryan JF, Burnet PWJ. The Microbiome in Psychology and Cognitive Neuroscience. Trends Cogn Sci. 2018 Jul;22(7):611-636.
–Saulnier DM, Ringel Y, Heyman MB, Foster JA, Bercik P, Shulman RJ, Versalovic J, Verdu EF, Dinan TG, Hecht G, Guarner F. The intestinal microbiome, probiotics and prebiotics in neurogastroenterology. Gut Microbes. 2013 Jan-Feb;4(1):17-27.
–Ramírez LA , Pérez-Padilla EA, García-Oscos F. , Salgado H, Atzori M., Pineda JC New theory on depression: a mood balance between the nervous and immune systems, with regulation of serotonin-kynurenine and the hypothalamic-pituitary-adrenal axis. Biomedical 2018;38:437-50