What Is The Gut-Brain Axis?

Gut Brain Axis Eli Brecher Nutritionist

Gut Brain Axis Eli Brecher Nutritionist

Have you heard of the Gut-Brain Axis? ⁠🧠 ⁠ ⁠

We’ve all experienced that feeling when we’re nervous: an upcoming exam, a presentation at work or even those butterflies in our stomach before a first date. This is the gut-brain axis at play. Those “butterflies” show that our brain and digestive system are directly connected to each other, so when we’re stressed, our gut is affected too.

In this blog post, you will learn:
👉🏼 why the gut is our “second brain” ⁠
👉🏼 how the gut and brain are connected⁠
👉🏼 what a “gut feeling” really is⁠

Do you struggle with digestive issues and want to improve your gut health? Head to Consultations to see how I can help you start your journey to the healthiest version of yourself today!


What is the Gut-Brain Axis?

The gut-brain axis is the bi-directional (two-way) communication between the enteric nervous system, which is found in the lining of the gut, and the central nervous system (the brain). The gut and the brain communicate with each other all day long, sending signals in both directions – from the gut to the brain and from the brain to the gut.

The gut and brain are physically connected via nerves such as the vagus nerve. They are also chemically connected via neurotransmitters such as serotonin (known as the “happy hormone”), as over 90% of our serotonin is produced in the gut. They also communicate via the immune system (through pattern recognition receptors) as well as the endocrine system and the HPA axis.

Gut Brain Axis Eli Brecher Nutritionist


The Second Brain

The gut is often referred to as the “second brain” because it has a nervous system with more neurotransmitters than the brain’s central nervous system. When we feel stressed, our brain activates the sympathetic nervous system, which is known as the “flight-or-fight” response. This prepares the body to protect itself against imminent danger (like running away from  a grizzly bear) by conserving functions that aren’t immediately necessary for survival, and that includes digestion.

The gut-brain axis explains why stress can cause digestive problems, like a stomach ache, nausea or heartburn. It also explains why those with gut issues like irritable bowel syndrome (IBS) may experience feelings of anxiety and depression – because it works both ways.


What About the Gut Microbiome?

The gut microbiome is the collection of trillions of bacteria, fungi and viruses that live inside your gut. Recent research suggests that the gut microbiome plays a role in the gut-brain axis, which is why it has become known as the microbiota-gut-brain axis.

The exact mechanisms through which the gut microbiota and the brain communicate are not yet clear. One way that they communicate is through neurotransmitters and metabolites produced by the gut microbiome, which communicate with the brain via the vagus nerve.


Gut Brain Axis Eli Brecher Nutritionist


While research is still emerging, we can use what we know about the gut-brain axis to support functional gut disorders like irritable bowel syndrome (IBS), as well as mental disorders including depression.

Every case is different, which is why I take a personalised approach with all of my 1:1 clients and tailor each nutrition plan and supplement recommendation to their unique needs and goals.


This is just a small insight into the types of things I discuss with my 1:1 clients. If you’re interested in working together to optimise your nutrition, transform your gut health and elevate your quality of life, please get in contact via Consultations or book in for a FREE call


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Check out my other nutrition-related blog posts below:




Clapp M et al. (2017) Gut Microbiota’s Effect on Mental Health: The Gut-Brain Axis. Clin. Pract; 7, 131-136

Farzi A, Fröhlich EE and Holzer P. (2018) Gut Microbiota and the Neuroendocrine System. Neurotherapeutics; 15(1):5-22

Wang HX and Wang YP. (2016) Gut Microbiota-brain Axis. Chin Med J; 5;129(19):2373-80