The Brain-gut Connection: Link Between Diet and Mental Health

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In recent years, there has been a growing interest in the role of nutrition in preventing and treating various diseases. However, using nutrients as a primary therapy for many illnesses is still relatively new. As a result, we often overlook the importance of a balanced and nutrient-rich diet in maintaining our physical and mental well-being.

We are what we eat.” Indeed, what we consume can significantly impact our overall health, and a lack of vital nutrients can lead to severe consequences, including mental health problems. In addition, the brain-gut connection highlights the intricate relationship between the gut and the brain and how it affects human psychology.

This article explores the importance of nutrients and diet in mental health and how they can help prevent, treat, and manage mental disorders.


Humans Have a “Second Brain” That Communicates With and Controls the Mind

The Brain-gut Connection

The brain-gut connection refers to the complex bidirectional communication network between the brain and the gut.

Scientists have suggested that the role of the gut in controlling human behavior is equally significant as the brain in our heads. Hence, the gut is often considered the body’s “second brain.” And there is a good reason for this recognition.

Looking inside your belly, you’ll discover that the gut is home to trillions of microorganisms collectively known as the gut microbiome. This vast army of microbes and the brain communicate through the gut-brain axis (GBA), which is composed of the central nervous system (CNS), the enteric nervous system (ENS), and the endocrine system.

Because the gut microbiome is crucial in regulating the gut-brain axis, it’s also vital to mental health. But how so, exactly?

The gut microbiome influences brain behavior by producing neurotransmitters and hormones that affect mood, cognition, and emotions. For example, gut bacteria produce 95% of total body serotonin, a neurotransmitter that regulates sleep. Also, they’re involved in producing gamma-aminobutyric acid (GABA), a regulator of anxiety and stress.

The gut microbiome also produces short-chain fatty acids (SCFAs) through the fermentation of dietary fiber, which has anti-inflammatory properties and can have a far-reaching effect on the CNS. Conversely, stress and emotional disturbances can impact the gut microbiome by altering its composition and function in producing crucial compounds.


Nutrients That Boost Mental Health



Macronutrients such as protein, carbohydrates, and fats are the foundation for physical health. Yet, little do we know they’re also essential for a good mentality.

Protein and amino acids (molecules that form proteins), such as tryptophan, are crucial for synthesizing neurotransmitters and neuromodulators. Thus, protein-rich foods can boost mental health by providing the necessary building blocks.

Meanwhile, carbohydrates, particularly complex carbohydrates such as whole grains and vegetables, provide glucose, the brain’s primary energy source. Adequate glucose levels are essential for good cognitive function and mood regulation.

Finally, fats, particularly omega-3 fatty acids found in fatty fish and nuts, are crucial for brain health and the maintenance of cell membranes. In addition, omega-3 fatty acids have been shown to improve mood and reduce symptoms of depression and anxiety.



Micronutrients, such as vitamins and minerals, are also crucial in maintaining good physical and mental health. In particular, some vitamins and minerals have been linked to positive health outcomes in patients with mental disorders.

For example, studies have shown that vitamin D deficiency is associated with depression, while supplementation with vitamin D can improve mood. Meanwhile, B vitamins, particularly B6, B9, and B12, are essential for neurotransmitter synthesis and have been linked to a reduced risk of depression and improved cognitive function.

Minerals such as iron, zinc, and magnesium also affect mental health. For example, iron is crucial for oxygen transport in the brain and cognitive function, while zinc and magnesium have been linked to improvements in depression and anxiety.


Foods That Negatively Affect Mental Health


As people say: “Where there is good, there is bad.” Sadly, this is true in everything.

While there are good foods to help with mental health, bad foods also get in the way and cause dreadful troubles for the brain-gut connection.

Processed foods, such as fast food, chips, and sweets, are often high in sugar, salt, and unhealthy fats. Consuming a diet high in these foods can lead to weight gain, inflammation, and oxidative stress, negatively impacting mental health.

Meanwhile, sugar and unhealthy fats can disrupt the gut microbiome, leading to dysbiosis linked to depression, anxiety, and other mental health disorders. Consuming high amounts of caffeine in coffee, tea, and energy drinks can also lead to increased anxiety, jitteriness, and disrupted sleep, negatively impacting mental health.

Alcohol is another beverage that can negatively impact mental health. If consumed in excess amounts, alcohol becomes a depressant that can disrupt the balance of neurotransmitters in the brain, leading to changes in mood and behavior.

Other foods and beverages that can impair your mental health are:

  • Refined carbohydrates, such as white bread and pasta
  • Saturated and trans fats, such as fried foods and fatty meats
  • Artificial additives, such as preservatives and food dyes
  • Sodium, such as processed meats and canned foods


Medical Nutrition Therapy for Mental Health

Medical nutrition therapy (MNT) is an emerging approach to preventing, treating, and managing mental health disorders. It is tailored to each individual’s needs to develop a nutrition plan and reinforce the brain-gut connection.

Nutrition through diet is a fundamental component of good mental health. Yet, it can sometimes be insufficient in quality. How so?

While it may be simple for most people to include enough foods (nutrient quantity) beneficial to the gut, only some manage to include enough types of foods (nutrient quality) providing unique nutrients that cannot be found in other foods.

For example, seafood is an excellent source of omega-3 fatty acids. While some plant-based sources, such as chia seeds and flaxseeds, also contain omega-3s, they do not provide the same type of omega-3s found in seafood.

Unfortunately, food variation does matter.

Research has shown people must consume 30 types of vegetables, fruits, nuts, and seeds per week to optimize the gut microbiome. This number highlights the need for a specialized approach to providing the body with nutrients from different sources.

Specialized approach? Different sources of nutrients? How can we make it possible?

The answer is medical nutrition therapy or MNT.

MNT can effectively manage mental health conditions such as depression, anxiety, and ADHD linked to gut microbiome imbalances and nutrient deficiencies.

Implementing MNT may involve increasing the intake of foods high in crucial nutrients such as omega-3 fatty acids, B vitamins, and magnesium and incorporating probiotics and prebiotics to support gut health. Also, MNT may involve eliminating or reducing the intake of foods detrimental to mental health, such as processed foods, caffeine, and alcohol.


Recent Evidence for Medical Nutrition Therapy

The scientific evidence linking nutrition quality achieved by medical nutrition therapy to mental health has progressively risen over the past few years.

The significance of nutrients for the prevention, treatment, or enhancement of treatment for mental illnesses has highlighted the brain-gut connection. Studies with high sample sizes and systematic reviews have also demonstrated it.

Below are the most recent studies collected in a systematic review published in the Indian Journal of Psychiatry, showing the vital role of nutritional psychiatry in the function of the human brain, starting from the gut.

Ames et al.High doses of vitamin therapy can remedy reduced enzyme activity caused by genetic polymorphisms that may contribute to mental disorders.
Rao et al.Various macro- and micro-nutrients can affect the onset, severity, and duration of depression.
Amminger et al.Omega 3 fatty acids can reduce the risk of developing schizophrenia in high-risk individuals.
Ross et al.Higher levels of phosphatidylcholine during pregnancy were associated with fewer social and attentional problems in children.
Jacka et al.Traditional dietary patterns of vegetables, fruits, meat, fish, and whole grains are associated with lower odds of major depression, dysthymia, and anxiety disorders.
Akbaraly et al.A whole food pattern is associated with lower odds of depression.
Sánchez-Villegas et al.A Mediterranean diet, consisting of vegetables, fruits, nuts, cereals, legumes, fish, and monounsaturated fatty acids, is associated with a lower risk of depression.
Nanri et al.High intakes of vegetables, fruits, soya products, mushrooms, seaweed, and fish decrease the risk of suicide.
Sarris et al.S-adenosylmethionine (SAMe) is superior to escitalopram and can reduce depressive symptoms.

Methylfolate, omega-3 fatty acids, and Vitamin D can also reduce depressive symptoms when used with antidepressants.

Dean et al.N-acetyl cysteine can significantly improve symptoms in bipolar disorder patients.


Bottom Line

The importance of nutrients and the brain-gut connection in mental health and human psychology cannot be understated. By making simple yet significant changes to our diets and lifestyles, we can reduce the risk of developing mental health disorders, manage existing ones, and improve our overall well-being.

Therefore, it is crucial to prioritize a balanced and varied diet that includes essential nutrients, vitamins, and minerals to support brain function and maintain optimal mental health. In addition, regular exercise, reducing stress, and getting enough sleep complement a healthy diet promoting good mental health.

With a little effort and conscious choices, we can take charge of our mental well-being and lead fulfilling lives.



Lieberman H. (1999). The Role of Protein and Amino Acids in Sustaining and Enhancing Performance. Institute of Medicine (US) Committee on Military Nutrition Research.

Mergenthaler P. et al. (2013). Sugar for the Brain: The Role of Glucose in Physiological and Pathological Brain Function. Trends in Neurosciences.

Ranjbar E. et al. (2013). Effects of Zinc Supplementation in Patients with Major Depression: A Randomized Clinical Trial. Iranian Journal of Psychiatry.

Abbaspour N. et al. (2014). Review on Iron and Its Importance for Human Health. Journal of Research in Medical Sciences.

Carabotti M. et al. (2015). The Gut-brain Axis: Interactions Between Enteric Microbiota, Central and Enteric Nervous Systems. Annals of Gastroenterology

Wani A. et al. (2015). Omega-3 Fatty Acids and the Treatment of Depression: A Review of Scientific Evidence. Integrative Medicine Research.

Raju M. (2017). Medical Nutrition in Mental Health and Disorders. Indian Journal of Psychiatry.

Appleton J. (2018). The Gut-Brain Axis: Influence of Microbiota on Mood and Mental Health. Integrative Medicine: A Clinician’s Journal.

Duranti S. et al. (2020). Bifidobacterium Adolescentis: A Key Member of the Human Gut Microbiota in the Production of GABA. Scientific Reports.

Menon V. et al. (2020). Vitamin D and Depression: A Critical Appraisal of the Evidence and Future Directions. Indian Journal of Psychological Medicine.

Wang Z. et al. (2021). B Vitamins and Prevention of Cognitive Decline and Incident Dementia: A Systematic Review and Meta-analysis. Nutrition Reviews.

Portincasa P. et al. (2022). Gut Microbiota and Short Chain Fatty Acids: Implications in Glucose Homeostasis. International Journal of Molecular Sciences.


If you have questions about the brain-gut connection or any health problems discussed here, connect with us and learn more. 

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