sBy: Victoria Piemontese, dietetic-student volunteer currently pursuing Bachelor of Applied Science in Food and Nutrition at Toronto Metropolitan University, reviewed by registered dietitian Natalie Walsh and the JM Nutrition Team
Have you heard about the gut-brain axis?
How about the second brain?
Did you know your body has two brains?
That’s right. The gut is the body’s “second brain”, as it has a very strong connection to the brain.
This gut-brain connection is greatly influenced by everyday lifestyle factors such as diet, stress, and exercise. These can all impact one’s health by affecting mood, cognition, and even the risk of developing various diseases and disorders.
For instance, have you ever felt nervous or stressed and noticed your stomach was upset, or your digestion was off?
Well, that’s a powerful example of the gut-brain axis in action.
So, let’s dive in!
What is the gut-brain axis?
The gut-brain axis involves a two-way communication between the central nervous system and the enteric nervous system, which is embedded in the lining of the gastrointestinal tract. This connection links our emotions and the activity of the intestines (Carabotti et al., 2015).
Therefore, this bidirectional communication means that the brain can impact gut function and health, and in turn, the gut can affect brain function and activity.
The gut microbiome
Undoubtedly, the gut microbiome plays an important role in the connections of the gut-brain axis.
The gut microbiome is the gastrointestinal (GI) ecosystem residing mostly in the large intestine, as well as the small intestine and stomach. It is a collection of various microbes living and functioning within the same space. The human microbiome is made up of microbes such as fungi, viruses, and bacteria (Flux & Lowry, 2019).
What’s more, the gut microbiome is responsible for different functions throughout the body such as digestion of food, absorption of nutrients, immune system support, and communication within the gut-brain axis (Flux & Lowry, 2019).
The gut microbiome can directly and indirectly impact the gut-brain axis. Various pathways of the brain, such as the endocrine, immune, and neural interact with the gut microbiome and different neurotransmitters, such as Gamma-aminobutyric acid (GABA), noradrenaline, serotonin, and dopamine.
These types of communications, occurring between the gut and brain, influence our mood and affect conditions such as anxiety and depression.
In addition, there may be an impact on gastrointestinal motility, causing symptoms such as constipation or diarrhea, and digestive conditions such as irritable bowel syndrome (IBS) (Margolis et al., 2021).
Related: How the Gut Microbiome Affects Children and Why It Matters
How does it work?
Gut-brain connection
Gut-to-brain communication occurs through the vagus nerve, connecting the GI tract to networks that regulate emotions in the brain.
Intestinal functions of the GI tract such as motility, secretion, and inflammation are regulated and influenced by microbes in the gut.
Vagus nerve receptors, such as those for serotonin (the body’s “feel-good” chemical), receive signals from the gut, which can impact mood (Margolis et al., 2021).
In addition to serotonin, other messengers like GABA and melatonin can affect microbial metabolism in the gut, impacting memory and learning through the sympathetic nervous system (Carabotti et al., 2015).
When the gut microbiome is distressed, altered, or imbalanced, an association with mood changes, anxiety, and depression is seen in the body (Margolis et al., 2021).
Brain-gut connection
On the other hand, there is a direct and indirect influence on the gut by the brain. Direct influence occurs through changes to the microbiome’s secretion, motility, and immune functions by the enteric nervous system (Margolis et al., 2021).
Additionally, the brain’s central nervous system directly communicates with neurotransmitter receptors on gut microbes (Carabotti et al., 2015).
Interestingly, the gut-brain axis connection is disrupted by various lifestyle factors (i.e. stress, sleep, diet, exercise, etc.), affecting the hypothalamic pituitary adrenal (HPA) axis and microbial composition in the gut, which plays a critical role in the development and severity of depression (Ray et al., 2025).
Furthermore, brain responses such as stress, anxiety, and depression can all have a significant impact on the gut. Symptoms such as nausea, indigestion, cramps, and bloating, as well as conditions such as IBS (with symptoms of constipation, diarrhea, and abdominal pain) can occur or be heightened (Margolis et al., 2021).
Related: Stress and nutrition connection
Stress affects the gut’s functioning by altering intestinal motility and transport, as well as the perception of body sensations (Moloney et al., 2015). Both the autonomic nervous system (ANS) and HPA directly and indirectly impact signalling and changes in the gut microbes (Carabotti et al., 2015).
So, as you can see, the gut-brain axis plays a very important role in our bodies that can positively or negatively impact our everyday life.
But what does this gut-brain connection mean for you? What can you do?
Lifestyle factors such as diet, sleep, stress, and exercise can all impact the function of the gut-brain axis.
Diet
First and foremost, a well-balanced diet can benefit the functions of the gut-brain axis.
Both our gut microbes and our overall health are positively influenced by a healthy diet. Consuming a variety of whole, minimally processed foods rich in nutrients like zinc, magnesium, and B vitamins can make the body feel good and can even help improve mood, depression, anxiety, and boost energy (Ray et al., 2025).
What does a balanced diet include?
Carbohydrates
Carbohydrates are essential for a healthy gut microbiome, as they provide a variety of benefits such as dietary fibre, prebiotics, antioxidants, and energy for the body (Schneider et al., 2024).
Examples:
Fruits: apples, oranges, bananas, berries, mangos, grapes, and cantaloupe
Vegetables: broccoli, cauliflower, carrots, peppers, lettuce, and potatoes
Fibre-rich foods: Beans, chia seeds, flaxseeds, psyllium, artichokes, bananas, and whole grains act as prebiotics, which feed our gut microbes.
Polyphenol-rich foods: Berries, nuts, beans, onions, spinach, asparagus, green tea, and sweet potatoes contain antioxidant and anti-inflammatory properties.
Protein
Proteins are the main source of amino acids, the building blocks of many body tissues. They are necessary for brain and gut health, as they help with neurotransmitter synthesis and influence the diversity of our gut microbes (Schneider et al., 2024).
Examples:
Animal-based: chicken, fish, dairy, and red meats (pork, beef, lamb, goat)
Plant-based: beans, lentils, nuts, seeds, and tofu
Fats
Unsaturated fatty acids have anti-inflammatory properties, while saturated fats cause inflammation and are linked with negative mental health symptoms (Schneider et al., 2024). Omega-3 fatty acids support cognitive function and mental health.
Related: Nutrition for mental health
Examples:
Unsaturated fat-rich foods: avocado, nuts (walnuts, almonds, cashews), seeds (pumpkin, sunflower, hemp), oils (olive, avocado)
Omega-3 fatty acid-rich foods: fatty fish (salmon, mackerel, sardines, oysters, anchovies), walnuts, and seeds (flax, chia) (Ray et al., 2025).
Reduce consumption of highly processed foods
Foods high in sugar, sodium, and saturated fat are associated with inflammation and poorer mental health (Schneider et al., 2024, Ray et al., 2025).
Examples:
Processed meats, packaged foods, sweets, and fried/fast-food
Reducing the intake of highly processed foods and incorporating more whole, minimally processed foods can benefit the brain and gut.
Sleep
Inadequate sleep is associated with depressive disorders, as pro-inflammatory cytokines disrupt immune function in the gut (Ray et al., 2025).
Therefore, improving sleep can support the gut-brain axis.
Ways to improve your sleep:
- Have a comfortable sleep environment (temperature, lighting, comfortable bed, pillow, and sheets).
- Maintain a consistent sleep schedule (i.e. go to sleep and wake up around the same time each day).
- Take time to wind down and relax before bed.
- Track your sleep cycle with an app (e.g., Sleep Cycle).
Related: Nutrition tips for sleep
Stress
Without a doubt, stress can affect the gut-brain axis by impacting the microbiome’s function, motility, immune system, and inflammation. Stress and the impact it has on the gut is also correlated with anxiety and depression (Moloney et al., 2015).
Ways to decrease stress:
- Mindfulness
- Talking to a friend
- Talking to a professional
- Physical activity
- Creative outlets
Related: dietitian’s support for mindful eating
Exercise
Physical activity is very beneficial for the body–something that our sports nutritionists feel is at times under-rated. It promotes overall health, as well as improves depression, mood, and anxiety (Flux & Lowry, 2019), amongst other things.
There are many ways to incorporate physical activity into your day. The most important thing is to find something you enjoy doing and stick to it.
Try these forms of exercise:
- Walking
- Running
- Yoga
- Biking
- Dancing
- Playing with your kids
- Taking the stairs instead of the elevator
- Fitness classes
- Sports
- And more
Gut-brain axis final thoughts
The power of the gut-brain axis and the effect it has on the body continue to be researched and understood.
Our current understanding of the gut-brain axis is a great reminder that our physical and mental health are greatly connected.
It is important to note that we can support our body with a balanced diet, prioritized sleep, managed stress, and physical activity.
Small changes to your daily lifestyle positively impact your gut, brain, and overall well-being. That much is clear.
So remember…listen to your gut, because it is your second brain!
Related: Gut Health 101
Conclusion
Should you feel you require personalized sessions for guidance around digestive health and brain health, book a free consultation or contact us for an appointment. As always if you have comments or questions, we encourage you to let us know.
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 : Quarterly Publication of the Hellenic Society of Gastroenterology, 28(2), 203. https://pmc.ncbi.nlm.nih.gov/articles/PMC4367209/
Flux, M. C., & Lowry, C. A. (2019). Finding intestinal fortitude: Integrating the microbiome into a holistic view of depression mechanisms, treatment, and resilience. Neurobiology of Disease, 135, 104578. https://doi.org/10.1016/j.nbd.2019.104578
Margolis, K. G., Cryan, J. F., & Mayer, E. A. (2021). The Microbiota-Gut-Brain Axis: From Motility to Mood. Gastroenterology, 160(5). https://doi.org/10.1053/j.gastro.2020.10.066
Moloney, R. D., Johnson, A. C., O’Mahony, S. M., Dinan, T. G., Greenwood-Van Meerveld, B., & Cryan, J. F. (2015). Stress and the Microbiota-Gut-Brain Axis in Visceral Pain: Relevance to Irritable Bowel Syndrome. CNS Neuroscience & Therapeutics, 22(2), 102–117. https://doi.org/10.1111/cns.12490
Ray, H., Janatum Khatum, Haldar, S., & Bhowmik, P. (2025). Second brain: reviewing the gut microbiome’s role in lifestyle diseases. BioTechnologia, 106(1), 103–122. https://doi.org/10.5114/bta/195495
Schneider, E., O’Riordan, K. J., Clarke, G., & Cryan, J. F. (2024). Feeding gut microbes to nourish the brain: unravelling the diet–microbiota–gut–brain axis. Nature Metabolism, 6. https://doi.org/10.1038/s42255-024-01108-6
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About Author:
Natalie Walsh is a North York dietitian who focuses on weight management counselling, menopause support, heart-healthy eating, digestive health, special diets and more.
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