- Marie Belzile-Davidson, MS, RDN, LD
Everything You Need to Know About the Gut-Brain Axis
Our brain, or "command central part 1" as I like to think of it, is connected to every part of our body. The link between our brain and the rest of our body is the central nervous system (CNS) -think spinal cord, nerves, etc. The brain uses our CNS to send signals out to orchestrate a variety of functions. The CNS is a two-way street though- it also receives signals from other parts of our body and sends them back to our brain.
If you have been following The Functional Kitchen, then you know that the gut and the brain are in close communication with one another. Guess which organ sends the most signals to the other though? Hint, it is not the brain. The gut actually sends significantly more signals to the brain than it receives from the brain. For that reason, I like to think of the gut as command central part 2. This line of communication that exists between our gut and brain is known as the gut-brain axis.
Let's take a look at your CNS, your gut, and how the two interact with one another.
Your Central Nervous System
There are two main "parts" that make up our nervous system -the somatic and the autonomic nervous system.
The somatic nervous system is the one that we control consciously. It allows us to carry out tasks like cooking and chewing our food, walking, doing any kind of movement practice, journaling, meditating, etc.
The autonomic nervous system manages all the body functions we do not consciously control but need to survive. It keeps our heart beating, allows us to breathe automatically, makes us sweat when we are too hot, triggers us to shiver when we need to create warmth, etc. The autonomic nervous system is further divided into the sympathetic, parasympathetic, and enteric nervous systems. Confused? I do not blame you - here is a simple breakdown of your CNS:
These three parts of the autonomic nervous system are all designed to help us survive in multiple ways. We may not directly control them but there are things we can do to influence them (more on that in a bit).
The sympathetic nervous system is our "fight or flight" mode. This kicks in when we sense danger (whether it is real or not) and when we are stressed. In this mode, your body is focused on working hard to get you out of that stressful or dangerous situation (i.e. powering your muscles and getting blood and oxygen where it needs to go). This uses a lot of energy. When you spend a lot of time in the sympathetic nervous system state, your body does not focus on properly digesting food, healing from illness or injury, or recovering from that intense exercise you did earlier in the day.
Your parasympathetic nervous system is your "rest and digest" mode. We are in this mode when our body feels safe (i.e. the danger has passed and we don't feel physically or emotionally stressed). In this state, our heart, lungs, and other muscles (including your digestive system) can properly do their jobs. We are secreting more digestive juices to break down food, we are absorbing more nutrients, and inflammation levels are lower, just to name a few benefits of this mode.
Onto the enteric nervous system. Its main responsibility is managing digestive processes. It spans from your esophagus all the way down to your colon (where food comes in to where waste leaves). This system is capable of functioning independently from the rest of the nervous system but it does receive input from your sympathetic (fight or flight) and parasympathetic (rest and digest) nervous system. This line of communication between the gut and the brain is the "gut-brain" axis we talked about a little earlier.
The Gut-Brain Axis
Ok, so how does this relate to your everyday life and health? Let's do a quick check-in as an example: when is the last time you did not feel some kind of stress? If it has been a while, you are not alone. We live in a world filled with real and perceived stressors! I am not just talking about the news, financial stress, and job stress. This also includes stressing about how to get your three kids to three different events with one car and not enough time, what to make for dinner because no one wants to eat the same thing, being unhappy with how your clothes fit, etc.
These stressors tip our brain off that we are not safe, activating that sympathetic nervous system (fight or flight mode). Our enteric nervous system (digest processes) is then informed by the sympathetic nervous system that we are not safe. So if this were a real conversation, it may go something like this:
brain to sympathetic nervous system: "Oh, there are some stressors we need to manage, get to work!"
sympathetic nervous system to brain: "On it, let's divert energy from other processes and focus on getting blood and oxygen to the muscles so we can fight off or run away from this stress."
sympathetic nervous system to enteric nervous system: "Hey buddy, we aren't safe right now so forget about digesting food well, we need energy to get out of this stressful situation!"
Constantly being stressed in one way or another can have some serious consequences. For example, we may not properly break down the protein we eat to build stronger muscles, no matter how much we exercise and how many grams of protein we take in. Additionally, we may not absorb all the vitamins and minerals we need, despite eating all the right things. If you exercise regularly and eat a well-balanced diet but still do not see the scale moving or are evening gaining weight, constant stress may be a part of it! Often being in "fight or flight" also means our intestines are chronically stressed so our gut microbiome can get all out of whack and the cells lining our gut that should be snug can start to separate and lead to leaky gut.
What is the main takeaway so far? Digestion, which is foundational to total health, is impacted by stress (from our lives, our thoughts, the environment) and what is happening in the rest of our body and mind! Remember, the gut also talks to our brain often so by that same token, what we eat and how we digest impacts the rest of our body and mind! While we cannot directly control our autonomic nervous system (sympathetic, parasympathetic, and enteric nervous system), we can influence it through food and lifestyle. Let's take a look:
How to Eat and De-stress for Better Gut-Brain Health
What foods should you be focusing on? If you read our last blog on How Food Affects Your Mood, you'll notice that the advice is the same because we are focusing on optimizing our gut health to positively impact that gut-brain axis!
Enjoy more vegetables and some fruit.
Fresh or frozen, both are great!
Focus on variety (think color, texture, preparations).
Go for whole fruits and vegetables over juices.
Eat enough fiber.
Check in here and see if you are eating enough fiber.
Foods that help you reach your fiber needs include vegetables, fruit, whole grains, legumes, and seeds.
Help support a healthy gut with fermented and probiotic-rich foods.
Look for fermented and probiotic-rich foods in the refrigerator section so you actually get live cultures.
Some foods include plain yogurt, heifer, sauerkraut, kimchi, pickles, and miso.
Limit added sugar
It is not a secret that added sugar is not our best friend (more on that here). We do not have to eliminate all of it but rather, focus on minimizing it mindfully.
Go for high-quality, minimally inflammatory protein.
Think wild-caught fish and seafood, organic poultry, and grass-fed red meat.
Limit inflammatory foods.
Some of the basics include minimizing trans fat, saturated fat, refined grains and flours, and added sugar.
Follow this link for a more detailed plan.
Vegetables and some fruit
Whole grains and fiber
How about stress? There are several ways to reduce or eliminate stress in our lives. Remember that your stressors are unique to you so there is no "one size fits all" approach. Some stress reduction techniques I love and recommend include:
Establishing a breath work practice
Setting and maintaining healthy boundaries
Getting adequate, restful sleep
Asking for help when you need it
Putting It All Together
The various parts of our bodies do not operate in silos. Everything is interconnected and the gut-brain axis is a perfect example of that. That is why our 1:1 dietitian nutrition coaching incorporates nutrition, movement, sleep, and mindset work to help you heal and feel your best.
If you feel like you are constantly living in "fight or flight" and are looking for ways to support your gut-brain axis, click here to schedule a complimentary call with one of our registered dietitians.
Cleveland Clinic. (2016, October 6). Gut-Brain Connection. Retrieved from
Harvard Health. (n.d.). The gut-brain connection. Retrieved from
Harvard Health. (2019, August 21). Stress and the sensitive gut. Retrieved from
Harvard Health. (2019, April 11). Brain-gut connection explains why integrative treatments can help relieve digestive ailments. Retrieved from
National Library of Medicine (2021, July 29). Anatomy, Autonomic Nervous System. Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK539845/
University of Calgary. (2018, December 1). Can a meal be medicine? How what we eat affects our gut health, which affects our wellness. Retrieved from