Are Your Brain and Your Gut BFFs?

Written by Clare Carrick ANutr BHSc (Nutrition and Health Promotion)

Scientifically reviewed by Dr Fathalla Ali, PHD Paediatrics


Are you and your BFF on the phone to each other whenever you have the chance? Texting about the latest season of Stranger Things…Sharing funny cat videos over breakfast…or FaceTiming the minute you have finished work?


Our world is so full of opportunities for connection these days that we can communicate with anyone we like, whenever we like…But, I can guarantee that, even if you feel like you never get off your phone, you still don’t chat to anyone as much as your gut and brain chat to each other… These two are the heroes of connection, chatting back-and-forth, non-stop.


The Brain-Gut-Microbiome Axis

Most of us intuitively understand that our gut and brain are connected in some way…When we’re nervous, we get butterflies in our stomach, and, when we eat something delicious, it makes us happy! But how do these two organs communicate with each other? Turns out, just like humans, the gut and brain have multiple modes of communication!


The gut and the brain are connected both physically and chemically, and, just like you and your BFF, they use a bunch of different communication methods to get their messages to each other, involving the nervous system, hormones and inflammation (1). 


Early Life Gut-Brain Programming

Communication between the gut microbiome and the brain are programmed in the first three years of a baby’s life, including the prenatal period, again highlighting how important this time period is for the future health of a baby (1). Studies have shown that any disruption in development during this time can influence the communication between the gut and the brain, and may even contribute to the development of things like IBS, autism, ADHD, obesity and anxiety later in life (1). It is also important to note that, whilst the programming occurs during these early years, these communication skills between the gut and the brain will be in a state of constant flux throughout life, affected by medications, diet, and stress levels (1). 


You’ve Got Some Nerve…

One of the key routes of communication between your brain, gut and gut bugs is via something called the vagus nerve, which is sometimes also referred to as ‘the sixth sense’ (2). This very astute nerve can sense small changes in your gut microbiome, and sends signals back to your central nervous system (CNS), made up mainly of your brain and spinal cord, prompting it into action (2)! Via the vagus nerve, your brain has the power to reduce peripheral inflammation and/or leaky gut (aka intestinal permeability), and it is also thought to have the ability to change your gut bug population (2)! The response of your CNS is important…it will either have an ‘adapted’ or ‘inappropriate’ response to the messages (2). An ‘adapted’ response is what you want…a suitable response to deal with any given situation, whereas an ‘inappropriate’ response may lead to gastrointestinal and neurodegenerative issues (2). 


Interrupting the Convo

One of the biggest interruptions to the communication between the gut and brain is stress! Stress stops the vagus nerve from doing its job properly, and can have a pretty damaging impact on the gastrointestinal tract and gut bugs (2).  A stress-induced increase in ‘leaky gut’ may mean that bacteria gets into places they’re not really supposed to be, increasing unwanted inflammation in the gut (3). Yet another reason to find things to help you wind down… join that meditation class, take up gardening, or get stuck into a good novel.


Tone it Up!

Just like we tone our muscles at the gym, our vagus nerve needs to stay ‘toned’ to function as it should! In fact, people with gut issues like IBS or IBD often have low vagal tone, although it’s difficult to tell whether it is the cause or effect of the gut symptoms (2). 

Exercises such as deep breathing or yoga practices may be helpful for some people to strengthen their vagal tone and improve their gut-brain communication (4).


  1. Osadchiy V, Martin CR, Mayer EA. The gut–brain axis and the microbiome: mechanisms and clinical implications. Clinical Gastroenterology and Hepatology. 2019 Jan 1;17(2):322-32.
  2. Bonaz B, Bazin T, Pellissier S. The vagus nerve at the interface of the microbiota-gut-brain axis. Frontiers in neuroscience. 2018 Feb 7;12:49.
  3. Martin CR, Osadchiy V, Kalani A, Mayer EA. The brain-gut-microbiome axis. Cellular and molecular gastroenterology and hepatology. 2018 Jan 1;6(2):133-48. 
  4. Magnon V, Dutheil F, Vallet GT. Benefits from one session of deep and slow breathing on vagal tone and anxiety in young and older adults. Scientific Reports. 2021 Sep 29;11(1):1-0.

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