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The Gut-Brain Axis

The Gut-Brain Axis: what it is, how it works, and how to regulate it

Have you ever thought about how people have always felt emotions in their guts? You’ve likely heard someone say these phrases:, “my stomach is in knots”, “listen to your gut”, “gut-wrenching experience” and “I feel butterflies in my stomach”.

Why do you think that is?

Well, the gut and the brain are SO connected. Our gut has an immense role to play in our brains, and our brain has a huge impact on our gut reactions too.

In the last couple of decades, science has discovered an important link between your gut and your nervous system. In fact, recent research has shown that there is a direct, bidirectional communication between our gut and our brain. This means that our brain impacts how our gut functions, but also our gut impacts how our brain functions and how we feel, both physically and emotionally. Activities that we thought occurred just in the brain, have now been largely found to occur in the gut.

The gut-brain axis involves a network of nerves, hormones, and microbiota that communicate between the gut and the brain. The nerves that connect the gut and the brain are called the enteric nervous system (ENS), which is often referred to as the "second brain" due to its complexity and similarity to the Central Nervous System (CNS). The ENS contains over 100 million nerve cells, which communicate with the CNS via the vagus nerve.

Hormones such as Ghrelin, leptin, and insulin also play a role in the gut-brain axis. These hormones are produced in the gut and are involved in regulating hunger, satiety, and energy metabolism. They also communicate with the brain to regulate mood and cognitive function.

The gut microbiome also plays a crucial role in the gut-brain axis. The gut contains trillions of bacteria, which help to digest food and produce essential nutrients. These bacteria also produce neurotransmitters such as serotonin, dopamine, and GABA, which are important for regulating mood and cognitive function. Did you know that 90% of serotonin (aka your happy hormone) and half of your dopamine (aka your pleasure hormone) is produced in the gut? That’s why Dysbiosis, or an imbalance of gut bacteria, has been linked to many health conditions, including depression, anxiety, and obesity.

That means the microorganisms in our gut directly impact the messages being sent to our brain. Like a two-lane highway, just as your mood influences and causes changes to your gut bacteria, your gut bacteria also influence your mood and this, in short, is what the whole gut-brain axis is about. This new area of research has shown us that in order for us to support our mental health, it’s essential to support our gut health, and in order to optimize our gut health, we need to support our mental health, too.

This is why stress affects our digestion!

Stress is one of the major triggers of gut issues. It’s why we get ‘butterflies in our stomach’ when we’re nervous, or when we have the urge to run to the bathroom before an exam or a big meeting at work. For some, stress speeds up gut motility and can cause diarrhea. For others, it can slow things down leading you to feel really bloated and constipated. It can make you more hungry – particularly for comfort foods – or it can destroy your appetite, making it hard to get the nutrients you need.

When we experience a stressor and our bodies shift into what we call the sympathetic nervous system, our adrenal glands release cortisol and signals to our various organs to put certain processes on hold so we can deal with the stressor at hand. When the Sympathetic Nervous System (also known as our fight or flight system) is active, all of our energy is directed towards fighting off a perceived stressor (which can be as simple as responding to an email!) and we see a significant decrease in digestive enzymes and usually a loss of appetite.

On the other hand, when we are present and relaxed, we activate our Parasympathetic Nervous System (also known as our rest and digest system). When the Parasympathetic Nervous System is activated, the body focuses its energy on digestion: we have increased blood flow to the digestive tract, we secrete more digestive enzymes and we have an increase in peristaltic movement.

I get it: avoiding stressors in our life can be tricky (albeit, almost impossible). But managing stress will not only have a direct impact on your mental health, but it’ll also have a profound impact on your gut health, and ultimately your digestion.

Here are some of my top lifestyle practices to decrease stress and by default, restore balance in your gut:

  • Journaling your thoughts and practicing gratitude: Journaling is a fantastic tool to incorporate in an individual’s daily life, whether that’s in a morning routine or evening routine. Practicing gratitude enhances your positive emotions, helps you get more joy out of positive experiences and helps you to respond well to challenges and stressors, improves your health and helps you have more satisfying relationships.

  • Breathing exercises: The diaphragm and intercostal muscles between the ribs are what controls the movement of breathing. When a person is under stress, their breathing becomes shallow and they use their shoulders to move air in and out of the lungs instead of the diaphragm. This pattern of breathing prolongs the feelings of stress. Deep breathing on the other hand, uses the whole diaphragm and activates the parasympathetic nervous system by stimulating the vagus nerve.

  • Meditation: Meditation is one of the best relaxation techniques and it also stimulates the vagus nerve. Studies have found that meditation reduces that sympathetic fight or flight response, it increases vagal tone, helping people respond better to the stresses in their life.

Here’s what to eat to support your gut health and your mental health

When it comes to supporting your mental health, one of the best things you can do is support your gut health. Thanks to the gut-brain axis, these two systems are so connected. Here are some foods to include in your diet to support your gut-brain axis:

  1. Fibre to provide fuel to our gut bugs: whole grains, chia seeds, psyllium husks, legumes, vegetables, fruits, oats, nuts, brown rice

  2. Fermented foods to replenish our gut microbiome: kombucha, kefir, sauerkraut, pickled vegetables, kimchi, tempeh

  3. Anti Inflammatory foods to support our brains and our guts: turmeric, ginger, walnuts, chia seeds, flaxseeds, avocados, green leafy vegetables, tomatoes, berries

  4. Serotonin/tryptophan-rich foods to support our happy hormones: banana, pineapple, tofu, tempeh, pumpkin seeds, sunflower seeds, cashews, almonds, legumes, oats, spinach

In summary, the gut-brain axis is a complex system that connects the gut and the brain. It involves a network of nerves, hormones, and microbiota that communicate bidirectionally to regulate many physiological functions, including digestion, metabolism, and mood. The bottom line: when your gut is out of balance, a chain reaction of imbalances occurs that interferes with your brain’s ability to do its job. Communication between your brain and your gut can work for you or it can work against you. In order to make them work for you, it’s important to make changes in your diet and your lifestyle to optimize your mental health and your physical health.


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