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Food & Mood: The Gut Brain Connection

August 3, 2018
Hormonal Birth Control? No thank you.
August 4, 2018

Gone are the days that we thought we only had one brain. That’s right – we now realise that we have two! The one you always knew you had and the one in the depths of your gut.

I t’s the one in your gut that is being dubbed your “primary brain” because the health of the one in our skull relies so heavily on it.

The reason for this is because of the vagus nerve – the longest nerve in the human body that stretches from the brainstem to the lowest viscera of your intestines. It is the communication highway between your gut and your brain and the quality of that communication depends on the quality of your gut microbiota.

The human gut contains 100 trillion microorganisms. That’s more cells than our entire body is made up of, and 100 times more genes than our genome - our entire set of DNA. It weighs about 1kg and the vast majority of it lives in the colon. The communication between the microbiota and the brain is bidirectional through multiple pathways, namely neural, endocrine, immune and metabolic.1 This is why alterations in our gut microbiota are linked to a range of different conditions including leaky gut, IBS, allergies and intolerances, poor immunity, obesity and metabolic disorders, all of which have an effect on our brain function and can lead to conditions such as depression, anxiety, dementia and Alzhiemer’s.2,3

Our gut bacteria also produce hundreds of neurotransmitters which the brain uses to regulate basic physiological processes as well as mental processes such as learning, memory and mood. For example, 95% of our body’s supply of serotonin, the neurotransmitter that stabilises our mood, is manufactured in the gut. As a result those with a poor diet increase their risk of developing depression by 25%.4


Nicola Miethke


November 10, 2018


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...our gut microbiota are linked to a range of different conditions, including leaky gut, IBS, allergies and intolerances, poor immunity, obesity and metabolic disorders – all of which have an effect on our brain function...

What causes alterations in our gut microbiota?

Our modern lifestyles are the biggest culprits when it comes to upsetting the environment within our gut, such as::

  • Poor diet i.e. high quantities of refined sugars, carbohydrates and saturated fats

  • Smoking

  • Stress

  • Lack of exercise

  • Overseas travel

  • Circadian disruption due to travel or shift work

  • Antibiotics

  • Vaccinations

  • Intensive use of disinfecting and cleaning products2,5,6

Which foods are good for our moods?

Our brain requires an array of vitamins and minerals, all three macronutrients i.e protein, fat and carbohydrates, and plenty of hydration to function optimally.

Fats: Between 50% and 60% of our brains are made up of fat. They are therefore an essential component for the structure of the brain as well as optimal brain signalling which reduces depressive-like behaviour.7

Sources: Oily fish (salmon, mackerel, sardines, anchovies), eggs, chia seeds, flax seeds, avocado, grass-fed meats.

Protein: Amino acids are the building blocks of every cell in the body including neurotransmitters such as serotonin and dopamine. Both of which are essential for boosting energy, improving mental clarity, reducing anxiety and initiating deep sleep.

Sources: Lean meat, poultry, fish, seafood, legumes, tofu/tempeh, nuts & seeds.

Carbohydrates: When I say carbohydrates, I’m not talking pasta and bread but rather fruits, vegetables, and wholegrains. Carbohydrates in the form of glucose are the preferred energy source of the brain and are an excellent form of fibre and prebiotics that feed the good bacteria in our gut promoting a healthy microbiota. These wholefoods are also where we get a lot of our B group vitamins, antioxidants and magnesium which are essential for the preventing neurodegenerative diseases and assisting with cognition, depression, anxiety, stress, mood, fatigue and migraines.

Sources: Fresh fruits and vegetable of all colours, wholegrains (e.g. brown rice, quinoa, oats, buckwheat).

Beyond mental health

Feeding our brains with the right balance of macro and micro nutrients will not only help to maintain healthy gut bacteria thus decreasing our chances of developing mental health issues, it will also help to:

  • Improve quality of sleep and reduce fatigue

  • Reduce the risk of developing dementia and Alzheimer’s

  • Improve our ability to deal with stress and avoid burnout

  • Reduce our reliance on medications

  • Reduce inflammation

  • Stimulate the growth of new brain cells

  • Improve the survival of brain cells7,8,9,10

We can see that adequate dietary intake and nutritional status have a profound effect on our gut microbiota and therefore on the health of our brain and the way that it functions. By ensuring that we are maximising our gut health through good diet and lifestyle practices we are able to reduce the risk of anxiety and depression, have more energy and focus, improve our mental clarity and cognition, and experience an overall improvement in our mood.

Can you notice a difference in your mental health status when your healthy diet and exercise practices slip?



1Bonaz, B., Bazin, T., & Pellissier, S. (2018). The Vagus Nerve at the Interface of the Microbiota-Gut-Brain Axis. Frontiers in neuroscience, 12, 49. doi:10.3389/fnins.2018.00049

2Evrensel, A., & Ceylan, M. E. (2015). The Gut-Brain Axis: The Missing Link in Depression. Clinical psychopharmacology and neuroscience: the official scientific journal of the Korean College of Neuropsychopharmacology, 13(3), 239-44.

3Singh, M. (2014). Mood, food, and obesity. Frontiers In Psychology, 5, 1-20. doi:10.3389/fpsyg.2014.00925

4Carpenter, S. (2012). That gut feeling. Retrieved 15 November 2018, from

5Conlon, M. A., & Bird, A. R. (2014). The impact of diet and lifestyle on gut microbiota and human health. Nutrients, 7(1), 17-44. doi:10.3390/nu7010017

6Lima-Ojeda, J., Rupprecht, R., & Baghai, T. (2017). “I Am I and My Bacterial Circumstances”: Linking Gut Microbiome, Neurodevelopment, and Depression. Frontiers In Psychiatry, 8. doi: 10.3389/fpsyt.2017.00153

7Larrieu, T., & Layé, S. (2018). Food for Mood: Relevance of Nutritional Omega-3 Fatty Acids for Depression and Anxiety. Frontiers In Physiology, 9, 1047. doi:10.3389/fphys.2018.01047

8Frank, S., Gonzalez, K., Lee-Ang, L., Young, M. C., Tamez, M., & Mattei, J. (2017). Diet and Sleep Physiology: Public Health and Clinical Implications. Frontiers In Neurology, 8, 393. doi:10.3389/fneur.2017.00393

9St-Onge, M. P., Mikic, A., & Pietrolungo, C. E. (2016). Effects of Diet on Sleep Quality. Advances In Nutrition, 7(5), 938-49. doi:10.3945/an.116.012336

10Rakesh, G., Szabo, S. T., Alexopoulos, G. S., & Zannas, A. S. (2017). Strategies for dementia prevention: latest evidence and implications. Therapeutic Advances in Chronic Disease, 8(8-9), 121-136.

11McEvoy, C. T., Guyer, H., Langa, K. M., & Yaffe, K. (2017). Neuroprotective Diets Are Associated with Better Cognitive Function: The Health and Retirement Study. Journal of the American Geriatrics Society, 65(8), 1857-1862.