Series: Gut Health
Article no.: 2
Highlight
- The gut-brain axis (GBA) is defined as the complex bidirectional communication that happens between the brain and the intestine.
- This interaction occurs mainly through signaling of the microbiome in our guts to our nervous system and vice versa.
- The main nerve system that is connecting the gut to the brain is the vagus nerve.
- Every individual has a unique gut microbiome profile.
- Disruptions in gut health may cause anxiety- and depression-like symptoms/behavior to show up.
- The population of gut microbiota in people with depression is found to be distinctively different to healthy individuals.
1. Introduction
It is not a new finding that our gut and brain are connected and communicating all the time. This relationship is known as the gut-brain axis (GBA) and it involves a two-way communication between the gut microbiota & our brain. Because of such influence, some even coined the gut as a human’s second brain. But how do they really relate and should we care about it?
2. Gut-brain relationship 1, 2
Enteric microbiota are the microorganisms that live in our intestinal tract. Some of them are good while some are harmful for us. The ratio and abundance of good to bad microorganisms in our intestines determine the health of our guts – and our overall health too.
Studies have shown that the interaction between our guts and our brain involves the following systems:
- Vagus nerve
- Sympathetic
- Endocrine
- Immune
- Humoral links
- Gut microbiota
Out of all these systems, the vagus nerve is said to be the most influential pathway in this communication. Vagus nerve extends from the brainstem to the abdomen through our neck & thorax (chest). Because of its relation to the abdomen, nutrition components in our guts also have an influence on its activities. This is also how we are able to perceive hunger & satiety.
Other functions of the vagus nerve include:
- Regulating the muscle movement for swallowing & vocalization
- Regulating the heart rate & stimulating heart rate reduction
- Regulating the secretion & smooth muscle contraction in the intestines
- Modulating inflammations coming from the intestines
- Maintaining the intestinal homeostasis
Aside from the vagus nerve, the microbiota in our guts also play a huge role in this communication. In fact, a number of brain health issues have been linked to the population and regulation of these tiny microorganisms residing in our intestines.
3. How does this affect us? 2,3
The interaction that occurs between our intestine and our brain can lead to many health outcomes, mainly in our brain.
Studies have shown the evidence that this interaction leads to indirect effects on the brain & behaviors. Supplementation with probiotics such as Lactobacillus rhamnosus has been shown to reduce the corticosterone level caused by stress. In turn, it also reduced the behavior related to stress & depression.
It is able to do so by altering the production of GABA in different regions of the brain. GABA is a chemical produced in our brain and essentially acts as a relaxant to our brain. The consumption of probiotics L. rhamnosus causes an alteration in which the GABA productions are the opposite of what a brain with depressive symptoms usually produces.
In different studies, it was evident that the composition of gut microbiota in patients with depression is a lot different from healthy individuals without depression. In fact, when the microbiota sample from those patients were transferred to a germ-free mice (mice without any microbes population in their guts), the mice ended up exhibiting depressive-like behaviors.
4. Conclusion
In essence, our gut becomes our second brain due to the direct interaction between our gut microbiome and the nerves in our intestines. The population of the intestinal microbiota determines our mental and overall well-being.
This is partly why individuals who suffer from gut issues may also have other health issues such as anxiety disorder, mental fog, memory loss, and restlessness.
Check out our next article here on how you can improve your gut health while improving your overall health at the same time. We will uncover methods involving dietary & behavioral changes that you might and might have not heard of.
References:
- Carabotti, M., Scirocco, A., Maselli, M. A., & Severi, C. (2015). The gut-brain axis: interactions between enteric microbiota, central and enteric nervous systems. Annals of gastroenterology, 28(2), 203–209.
- Breit, S., Kupferberg, A., Rogler, G., & Hasler, G. (2018). Vagus nerve as modulator of the BRAIN–GUT axis in psychiatric and inflammatory disorders. Frontiers in Psychiatry, 9. https://doi.org/10.3389/fpsyt.2018.00044
- Dinan TG, Stanton C, Cryan JF. Psychobiotics: a novel class of psychotropic. Biol Psychiatry (2013) 74:720–6. doi:10.1016/j.biopsych.2013.05.001
2 thoughts on “The gut-brain relationship – how is our gut connected to our brain”
Good post. I learn something new and challenging on blogs I stumbleupon on a daily basis. Its always useful to read content from other writers and use a little something from their sites.
Good post. I learn something new and challenging on blogs I stumbleupon everyday. It will always be interesting to read articles from other authors and use a little something from their sites.