Have you ever felt butterflies in your stomach? Emotions are connected to our gut, as well as the brain function. This is known as the gut-brain axis.
Your brain affects your gut health, and vice versa. In between these two points, we have the gut microbiota, which largely affects the gut-brain axis.
In this post, we'll review the impact of the gut microbiota in the gut-brain axis!
These microorganisms have established, through evolution, a symbiotic relationship with the host (humans).
While you give them a place to live, they benefit you by supporting your intestinal development and maturation (source)
Health Benefits of the Gut Microbiota
Inside you there are more bacterial cells than human cells... these microorganisms can really impact your health.
The gut microbiota has a big word in your health. Although research is still in progress, we know a bit of how the gut microbiota can benefit you!
There are four main functions the gut microbiota shows to improve:
Role of the Gut Microbiota in Your Health
Metabolic Function: The gut microbiota can help your digestion and convert them in nutrients you can use to produce energy (source)
Inmunity: The gut microbiota improves permeability of the intestinal barrier (source). It also interacts and boosts the inmune system (source).
Prevent Diseases: The 'good' bacteria prevents from the 'bad' bacteria to colonize our gut. This lowers the risk of diseases, and improves your overall health.
Brain Function: The connection between the brain and gut is interfered by the gut microbiota. But more about this in the next 5min... Scroll down!!
The Gut-Brain Axis
Have you ever felt butterflies in your stomach? Have you felt stomach pain when you were going through tough moments?
Your brain and gut are connected through the gut-brain axis. Your brain affects your gut health and your gut may even affect your brain health (source)
Inserting the gut microbiota in the equation, we end up with the microbiota–gut–brain (MGB or BGM) axis (source).
This concept refers to the role of the gut microbiota in the biochemical signaliging event between the central nervous system and gastrointestinal tract
Scientific Definition - Gut-Brain Axis
The gut-brain axis (GBA) consists of bidirectional communication between the central and the enteric nervous system, linking emotional and cognitive centers of the brain with peripheral intestinal functions (source)
The enteric nervous system is independent of the central nervous system. It includes neural circuits responsible of motor functions and other related tasks.
The vagus nerve connects the gut and brain. It sends biochemical signals in both directions (source). It acts as the highway between both structures.
The Gut-Brain Communication
The gut and brain are strongly connected. Your brain is able to 'sense' the environment in your gut, as well as you gut modulates depending on your 'brain status'.
The mechanisms proposed for the communication between the gut and brain rely on 5 different pathways:
How do the gut and brain communicate?
Vagus Nerve: the vagus nerve is the main neural channel. It creates a two-ways highway between both organs (study)
Metabolites: the gut microbiota produce a series of metabolites that cross the blood-brain barrier and interact with the brain (study)
Inflammation: the gut microbiota is a good modulator of inmunity and inflammation (study). The brain is highly susceptible to these two.
Enteric Nervous System: the enteric nervous system is independent of the central nervous system. It's able to drive electrical signals throughout the digestive system and give feedback to the central nervous system.
Neurotransmitters: Almost 95% of serotonin is produced by the gut microbiota(study), but other molecules such as dopamine or GABA are also produced there (study)
The Gut Microbiome and the Gut-Brain Axis
As part of your enteric system, the gut microbiota can affect your mood, prevent brain disorders, or even improve your cognitive function.
The Gut Microbiota can Improve your Mood
There's a relation between your gut health and your mood.
Germ-free animal experiments and human studies have evdienced the impact of the gut microbiota in your mood (study).
Microorganisms in your gut produce metabolites called short chain fatty acids (SCFAs). These compounds are able to cross the blood-brain barrier, acting as decisive humoral influencers (study).
The contribution of the gut microbiota in inflammation, inmunity, intestine permeability, production of bioactive peptides,... may affect your mood and brain function as well (study)
The Gut Microbiota May Prevent Mental Disorders
The effect of the gut-brain axis on preventing mental disorders has been largely studied.
Different strains seem to have different roles on the development of different mental disorders.
Through research, we are now able to identify the major responsible microorganism species for the main mental disorders.
To date, we know that the gut microbiota and gut-brain axis may improve the status of MDD, BPAD, anxiety, psychosis, and neurodegenerative disorders (study)
The Gut Microbiota on the Brain Function
The gut microbiota acts on the development, physiology, and cognitive functions of the brain (source).
The intestinal microbiota is able to produce neurotransmitters such as dopamine, serotonin, norepinephrine, and δ-amino butyric acids (GABA)
Specific microorganisms have been identified as major responsibles of learning and working memory (study), or neurodevelopment (study)
Conclusion
The gut microbiota is part of the microbiota-gut-brain axis. It may affect your mood, delay or prevent mental disorders, and improve your brain function.
However, we are still lacking of research to conclude and understand the effects of the gut microbiota in your brain health!
