The Gut-Brain Connection: How Diet Influences Mental Health

By Bryn Durocher

As a teenager, I wanted real solutions to my mental health problems, and I thought that having a healthy diet seemed less significant. Nevertheless, the diet has many different connections to my mental health. We know that mental health can affect physical health, but it goes the other way, and your diet is heavily involved. 

An article by Carabotti and colleagues (2015) explains it. Unsurprisingly, there is a name for this communication; the connection linking the gut and the brain is called the “gut-brain axis. This relationship runs between the central and enteric (relating to the intestines) nervous systems. It connects the brain’s emotional and cognitive (mental processes) parts with operations of the peripheral intestines. This system runs both ways, which means it affects mental health. It was proven through precise interactions between central nervous disorders (such as anxiety and depression), microbiota (healthy organisms in your gut) changes and intestine disorders. The gut-brain axis also keeps your gastrointestinal tract in balance and includes many other parts of your body, such as the autonomic nervous system (which controls heart rate, breathing and more)

We want to focus on the gut-to-brain portion of the gut-brain axis since we are interested in mental health.

The gut-to-brain system affects the brain’s emotion, motivation and more significant cognitive functions through connection and communication with the brain (Carabotti et al., 2015). Researchers have found that gut microbiota is essential for the gut-brain axis, in other words, the pathways to the brain (Carabotti et al., 2015). Most importantly, the food we eat affects the microbiota, as discussed in the next paragraph. Keeping your “microbiome” healthy will help ensure your brain is healthy by reducing anxiety and enhancing cognitive, emotional and motivational functions (Carabotti et al., 2015). Gut bacteria also promote the creation, operation and transportation of neurotransmitters (Chen et al., 2021), chemicals in your brain that have innumerable functions. The bacteria do this by consuming the nutrients from the food you eat. Neurotransmitters aid in the communication between neurons (Sheffler et al., 2023), which are little cells in your brain and body that allow your every function (NINDS, 2023). Dopamine and serotonin are neurotransmitters: these are the substances that significantly influence your mood, thus establishing a direct connection between diet and mood. 

The food we eat can influence the connection between gut and mental health. In other words, a balanced diet helps to achieve better mental wellbeing. Here are some eating tips from The Canadian Digestive Health Foundation to improve your microbiome health and, consequently, your mental health: 

  1. Eat plenty of vegetables; they contain fibre that microbiota can eat
  2. Limit sugar and processed foods that give nothing to your health or microbiota
  3. Try probiotics such as yogurt; probiotics have healthy bacteria in them that add to your gut
  4. Cut back on red meat. It tends to contain unhealthy antibiotics (they stop bacteria).

The foods we eat affect our mood, emotions and cognitive functions through nutritional deficiency. Lacking vitamin B12, B9 and zinc, for example, can cause symptoms such as low mood, fatigue, and cognitive decline (Lachance et Ramsey, 2015). Lacking Omega-3 Fatty Acids affects neurotransmission, functioning, and mood (Lachance et Ramsey, 2015). Your brain also needs good fuel to function. You will not feel pleased if you run on low like a car. 

Adding some healthy food options into your life can even be made fun through trying different healthy food plans. Many have developed over the years, and their contents might surprise you. We will review them below.

The keto diet and mental health: You might have heard of this one or even know someone on it. The keto diet is low-fat, high-carbohydrates and average protein (Tillery et al., 2021). Instead of consuming carbohydrates, the body uses ketones for energy, a chemical produced when it breaks down fat (Tillery et al., 2021). Not only does the keto diet reduce weight for most people, influencing a more positive view of the self, but it also improves “mood, cognition, communication skills, energy, anxiety, and auditory and visual hallucinations” (Tillery et al., 2021). The diet also helps reduce mental illnesses such as depression and schizophrenia (Tillery et al., 2021). Some theories as to why the keto diet is so effective for mental health include raising the amount of GABA in the brain. This neurotransmitter has many functions, including reducing anxiety and possibly even depression (Luscher et al., 2010). This diet, like most, is customizable, and the amount of carbohydrates can be changed to fit your personal goals.

The plant-based diet and mental health: When examining the research, the results on whether a plant-based diet is helpful for mental health seem controversial. However, we know that eating healthy improves mental health, and a plant-based diet has many healthy components. “Indeed, specific plant-derived foods like whole grains, vegetables, legumes, nuts, and fruits are recognized for their health advantages. Conversely, excessive consumption of certain items like refined grains, fried potatoes, sugary treats, and fruit juices is generally considered detrimental to health” (Rossa-Roccor et al., 2021). A plant-based diet is beneficial for cognitive health due to nutrients and a reduced risk of heart diseases that would negatively affect the brain (Vasan, 2021). If the idea of adopting a plant-based diet is on your mind, ensure that no nutrients or vitamins are missing: if they are, consider taking supplements or modifying the diet. The plant- based diet benefits can be favorable for a few, but for some it may not as there have been reports of increased depression symptoms Just monitor yourself and consult a nutritionist or a dietician to make sure that this diet is proper for you. 

The Mediterranean diet and mental health comprise fruits and vegetables, whole grains, and legumes, nuts, fish, white meats, olive oil, moderate amounts of fermented dairy products, small amounts of red meat, and wine at meals (Ventriglio, 2020). It is considered one of the healthiest diets, and it is abundant in nutrients we have already discussed as vital for mental health, such as omega-3 fatty acids, fibres, antioxidants and probiotics (Ventriglio, 2020). The omega-3 fatty acids were associated with good mental health when the Mediterranean diet was tested on study participants (Ventriglio, 2020). Researchers also witnessed decreased depressive symptoms (Ventriglio, 2020), with diet, microbiota and the mechanisms involved in depression all being linked (Marx et al., 2021). Additionally, brain health, diet, and emotional wellbeing, in general, are uplifted through the Mediterranean diet (Marx et al., 2021).

In summary, proper nutrition leads to a healthier brain through the gut-brain axis. Plenty of vitamins and nutrients will determine the amount and diversity of microbiota/bacteria in the gut (Zhang, 2022). These microbiotas increase neurotransmitters, essential chemicals in the brain, such as GABA, and improve cognition, mood, and emotions. To augment nutrition, consider whether your current diet is the perfect plan for your health by keeping track of what you eat in a day and consult a licensed dietician or a nutritionist for a food plan that suits you best. After all, a healthier lifestyle has way more advantages than disadvantages.


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, 28(2), 203–209.

CDHF. (2023, June 7). Ten ways to strengthen your microbiome. Canadian Digestive Health Foundation.

Chen, Y., Xu, J., & Chen, Y. (2021). Regulation of Neurotransmitters by the Gut Microbiota and Effects on Cognition in Neurological Disorders. Nutrients, 13(6), 2099.

Lachance, L., & Ramsey, D. (2015). Food, mood, and brain health: implications for the modern clinician. Missouri Medicine, 112(2), 111–115.

Luscher, B., Shen, Q., & Sahir, N. (2011). The GABAergic deficit hypothesis of major depressive disorder. Molecular psychiatry, 16(4), 383–406.

Marx, Lane, M., Hockey, M., Aslam, H., Berk, M., Walder, K., Borsini, A., Firth, J., Pariante, C. M., Berding, K., Cryan, J. F., Clarke, G., Craig, J. M., Su, K.-P., Mischoulon, D., Gomez-Pinilla, F., Foster, J. A., Cani, P. D., Thuret, S., … Jacka, F. N. (2021). Diet and depression: exploring the biological mechanisms of action. Molecular Psychiatry, 26(1), 134–150.

NINDS. (2023). Brain basics: The life and death of a neuron. National Institute of Neurological Disorders and Stroke.

Rossa-Roccor, V., Richardson, C. G., Murphy, R. A., & Gadermann, A. M. (2021). The association between diet and mental health and wellbeing in young adults within a biopsychosocial framework. PloS one, 16(6), e0252358.

Sheffler, ZM., Reddy, V., Pillarisetty, LS (2023). Physiology, Neurotransmitters. Treasure Island (FL): StatPearls Publishing,

Tillery, E. E., Ellis, K. D., Threatt, T. B., Reyes, H. A., Plummer, C. S., & Barney, L. R. (2021). The use of the ketogenic diet in the treatment of psychiatric disorders. The mental health clinician, 11(3), 211–219.

Vasan (2021). Plant-based Diets Improve Cardiac Function, Cognitive Health. Boston University Chobanian & Avedisian School of Medicine.

Ventriglio, A., Sancassiani, F., Contu, M. P., Latorre, M., Di Slavatore, M., Fornaro, M., & Bhugra, (2020). Mediterranean Diet and its Benefits on Health and Mental Health: A Literature Review. Clinical practice and epidemiology in mental health: CP & EMH, 16(Suppl-1), 156–164.