The Probiotics and Mental health relationship is at the heart of numerous interrogations. Talking about the « gut-brain » axis has become so widespread that this relationship is now automatically accepted.
However, we can wonder what mechanisms are synthesized by this expression? How to take care of your gut with probiotics ? How can probiotics intake positively act on the brain ? In other words, why do probiotics improve mental health ?
The intestine is considered by scientists as our second brain. This status is given to the gut because hundreds of millions of neurons can be found in it. They ensure the contractions pacing the food flow.
Moreover, the gut is populated by billions of bacteria composing the intestinal microbiota. As a reminder, the microbiota is a complex combination of non-pathogenic bacteria, viruses, protozoans and fungi populating the intestine.
The neurons and the intestinal microbiota both play a crucial part in intestine-brain communication (the famous « gut-brain » axis) and can go as far as influencing our mood.
- The gut-brain communication
As mentioned earlier, there is a complex communication system between the intestine and the brain: the gut-brain axis.
Indeed, the gut conveys information to the brain and vice versa. It is known as two-way communication. This communication can occur according to two tracks: the direct and indirect pathways.
- The direct pathway
The brain is directly connected to the gut via the vagus nerve. It is worth highlighting that the vagus nerve is the nerve that, when hyper stimulated, can lead to reflex syncope.
This path is extremely fast (around one second). The information, like hunger and satiety (due to nutrient quality), is first secreted by the gut through chemical substances and is then transformed into electric signals. Those electric signals transit through the vagus nerve, like in a high-speed tunnel.
The neurons composing the vagus nerve can also detect the quantity and nature of the microorganisms composing the intestinal microbiota.
- The indirect pathway
The gut and the brain can communicate in a more indirect way, through blood flow. Thus, any molecule circulating in the blood journeys through the gut and the brain, passing through the whole body. However, this pathway is slower than the previous one (around one minute).
It allows the brain, for example, to act on the gut through the production of hormones released in the blood (the hormones are molecules which travel specifically on long distances via blood flow).
In the same way, the intestinal microbiota produces molecules ending up in our blood flow. Those molecules are then decoded by specific receptors in the brain. (1.)
- What are the consequences of imbalance on the “gut-brain” axis ?
The communication between the gut and the brain is based on a harmonious yet weak balance. Therefore, some elements like the composition of the microbiota on the one hand or stress on the other hand, can be the cause of different disorders.
- Microbiota imbalance
An imbalance can be caused by the modification of the nature or quantity of microorganisms composing the microbiota. In fact, some strains can become overabundant. Thus, the molecules sent in the blood by the microbiota will suffer modifications. This can lead to intestinal disorders.
Besides, if the communication through the blood pathway is disturbed, it can influence the distribution of a hormone to the brain: Serotonin (the happiness hormone). Yet, its transit being modified, it is not considered by the brain and the whole body does not benefit from the happiness hormone. (2.) This can explain, for instance, the higher rate of depression and anxiety in patients with intestinal disorders. (3.)
- Stress perceived by the brain
When we are under stress, the brain produces a hormone called cortisol. This hormone can, among other things, upset digestion. For example, acute stress can quicken digestion and create intestinal disorders.
The mechanisms reacting to gut-brain communication are particularly complex and the mechanisms between the microbiota and the brain are still not fully known to this day. It is necessary to deepen those notions to unravel them more precisely.
- The positive influence of probiotics on mental health
You got it, it is important to maintain one’s healthy microbiota in order to maintain one’s mental health.
Thus, to maintain a healthy microbiota, it is possible to act on its composition by bringing an external source of bacteria: probiotics. A probiotic supplementation allows to homogenize the quantity and the nature of bacteria contained in the intestinal microbiota. This is how the intestinal microbiota can be kept healthy.
Let’s take the example of the bacteria Bifidobacterium longum, Lactobacillus helveticus and Lactobacillus Rhamnosus. Those bacteria inhibit the growth of pathogenic agents and allow to maintain a healthy microbiota.
The use of probiotics has therefore the potential to keep the microbiota healthy which positively impacts our mental health. This is a piece of information to make us smile!
Of course, if you are looking for mental health food supplements containing probiotics (specially to fight stress), Kares-up offers tailored or ready for market formulations.
Florelle Charre, Neutraceutical R&D Engineer
Raphaëlle Da Costa, Founder
—————————————————————
- Arentsen T, Qian Y, Gkotzis S, Femenia T, Wang T, Udekwu K, Forssberg H, Diaz Heijtz R. The bacterial peptidoglycan-sensing molecule Pglyrp2 modulates brain development and behavior. Mol Psychiatry. [on line] 15 nov 2016;
- Stasi C, Sadalla S, Milani S. The relationship between the serotonin metabolism, gut-microbiota and the gut-brain axis. Curr Drug Metab. [on line] 24 sep 2019;
- Deutsch D, Bouchoucha M, Devroede G, Raynaud JJ, Sabate JM, Benamouzig R. Functional gastrointestinal disorders as predictors of suicidal ideation. An observational study. Eur J Gastroenterol Amp Hepatol.[on line] 6 juil 2021;
