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This post is by guest blogger Matthew Savage 

Hippocrates is credited with saying “all disease begins in the gut”, bringing on “dark moods” and other changes in behaviour (Svoboda, 2020). For centuries, scientists have been linking the gut with different types of behaviour and mental health conditions and with bacterial cells outnumbering human cells in the body by a factor of 1.3 to 1, there is much to be examined. More recent research has started to place the link between the gut and brain as a major potential avenue for mental health treatment. For example, around 90 percent of the serotonin in your body is produced by bacteria in your gut, suggesting that treatments which can improve our levels of these bacteria have potential to help those who suffer with low mood by stimulating serotonin production. This link between gut and brain is known as the “gut-brain axis”.

The Gut-brain axis

The gut-brain axis (GBA) is a bidirectional link between the central nervous system and the enteric (intestinal) nervous system of the body. The gut can have influence on neurotransmitters which affect stress, mood and behaviour and this leads to a loop whereby the brain has influence on mortality, secretion, nutrient balance and microbial balance. As early as 1998, it was found that certain unique bacterium would cause anxiety-like behaviours in mice and this was associated with activation of neuronal regions in the brain that were dependent on information received from the gut via the vagus nerve (Appleton, 2018). In addition to this, the discovery of the microbiome over the last 20 years and the development of new technologies to study it has really increased the possibilities of utilising this new knowledge base for our health.

How can our microbiome affect our wellbeing?

Over the past decade, gut bacteria has been studied and good and bad compounds have been discovered. Their effects on the mind are varied, with some bacteria generating acids which reduce our bodies production of dopamine and serotonin. Others enhance anti-inflammatory substances that support and boost the gut microbiome, the name given to the trillions of bacteria within our gut. Studies have suggested that disruption to the microbiota can impair physical and mental health and could be the reasons for an impaired immune system in some people (Aziz et al, 2014). There have been many links made between people with Irritable Bowel Syndrome and depressive episodes and certain dietary changes, such as gluten-free diets, have also been seen to reduce symptoms in schizophrenic patients. Now, with many studies suggesting the importance of gut health in reducing clinical conditions, it is important to understand that these changes can also help us all with maintaining positive wellbeing.

Changes we can make to improve our gut-brain functioning

With the probiotic market projected to grow to £48 billion by 2023 (Hancock, 2017), there are many different products being produced to look to enhance positive gut bacteria. Changes we can make to our diet include:

  • Mediterranean diets which is high in fibre, polyphenols and unsaturated fatty acids can result in the production anti-inflammatory substances which support positive mental wellbeing
  • Fermented Foods, such as kimchi (fermented and picked vegetables), kombucha (fermented tea) and fermented cheese may contain Lactobacillus helveticus or Lactobacillus acidophilus, substances which are said to have anti-depressive effects
  • L. acidophilus is said to prevent inflammatory substances from entering the brain via the gut-brain axis. It can be taken as a supplement and is also found in some yoghurt varieties.
  • L. helveticus and Bifidobacterium longum are a bacterial duo. Participants in studies have reported a drop in depressive symptoms with the bacteria potentially reducing Cortisol levels. One study also suggests that B. longum relieves IBS by restoring the function of cells which aid in healthy defecation habits. These are again available as a supplement.
  • Reducing our intake of refined carbohydrates, such as white bread, pasta and rice has also been linked with the reduction of depressive symptoms. Food high on the Glycaemic Index lead to spikes in blood insulin levels, undermining our psychological wellbeing. Replace refined carbohydrates with wholegrains has been shown to be beneficial for both our heart and our minds.

About Matt Savage

Matthew Savage has an MSc in Psychology, is a qualified personal trainer, and has worked within the field of cognitive rehabilitation for 5 years. He is an FA qualified football coach, with a keen interest in moral behaviour and wellbeing within team sports. 


Appleton J. (2018). The Gut-Brain Axis: Influence of Microbiota on Mood and Mental Health. Integrative medicine (Encinitas, Calif.), 17(4), 28–32.

Aziz Q, Doré J, Emmanuel A, Guarner F, Quigley EM. Gut microbiota and gastrointestinal health: current concepts and future directions. Neurogastroenterol Motil. 2013;25:4–15.

Rege S. The Simplified Guide to the Gut-Brain Axis – How the Gut and The Brain Talk to Each Other – Psychscencehub [Internet]. 2017 [cited 13/10/2020]. Available from:

Svoboda E. Gut Bacteria's Role in Anxiety and Depression: It’s Not Just In Your Head – Discovery Magazine. [Internet]. 2020 [cited 12/10/2020]. Available from:

Gut Brain


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