What Is The Gut Brain Axis?

Ankylosing Spondylitis

What Is The Gut Brain Axis?

The axis is made up of several communication pathways between the gut and the brain. These include:

  • An immune pathway
  • A hormone pathway
  • A metabolite pathway
  • A neurological pathway

In the most simplistic terms these pathways, which we refer to as the gut brain axis, are what interconnect these two areas of the body and partly explain why psychological stress can cause symptoms such as bloating, diarrhoea, constipation and abdominal pain, and, why imbalances in our gut health might contribute to mood based disordered such as depression.

How Does The Gut Brain Axis Work?

  • The neurological pathway is made up the vagus nerve. Vagus in latin mean wandering so you can invision what this serve looks like – branching out from the base of the brain and connecting all our vital organs in the torso.
  • The immune pathway is made up cytokines – these are immune cells involved in the inflammatory response.
  • The hormone pathway includes hormones such as cortisol 0 the stress hormone.
  • The metabolite pathway includes short chain fatty acids – these are produced by bacteria in our large intestine fermenting our dietary fibre. These SCFA’s can travel across the gut wall, into circulation and in to the nervous system.

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The Gut Brain Axis Diet

There is no specific diet to optimise the axis however supporting overall gut health may be helpful. Some of the most important considerations then include:

  1. Eating a wide range of plant foods. I recommend a daily goal, and a weekly goal here:
    1. The saying is eat a rainbow a day and thus ensuring you eat at last one portion of food from each of the colour groups may be important.
    2. Aim for 30+ different plant foods per week (vegetable, fruit, herbs, spices, nuts, seeds, pulses, lentils, legumes, beans, whole grains).
  2. Eat adequate amounts of healthy fats – aim to eat oily fish three times per week, avocados, nut, seeds, eggs, olive oil, ghee, grass fed dairy if tolerated.
  3. Eat fermented foods regularly – kombucha, kefir, kimchi and sauerkraut are the most popular options.

These are all bottom-up considerations (things that support gut health which may influence brain health). But don’t forget the important role that sleep, exercise and managing stress also play on both brain health and gut health. As always we need to focus on a lifestyle, not just a diet.

Gut Brain Axis Supplements

Things to consider to support gut health include:

  • Probiotics: some strains of probiotic are termed psycobiotics as they have shown in studies to influence mood and behaviour. An example of this is L. plantarum 299v. This is found in the supplement Ideal Bowel Support by Jarrow: click here. Receive 10% off by using my name (Alex Manos) during check out.
  • Omega 3: these healthy anti-inflammatory fats have been shown to increase butyrate producing bacteria and are helpful for brain health. Remember we mention butyrate earlier as a short chain fatty acid which make up part of the gut-brain axis. There is a product by APEX called ‘Brain E DHA 1200-TG (K114)’ which is an excellent option. It is available via Amrita but you will need to register to be able to order it: click here.
  • Prebiotics: I like Bimuno available from Amazon (click here). I add this to my morning coffee for a gut-friendly start to the day!
  • Vitamin D may have exert some of its positive influence via the gut-brain axis.

Gut Brain Axis: Depression & Anxiety

Research has demonstrated that imbalances in the gut can contribute to mood based conditions such as depression.

The gut microbiome has been discussed in the research as a “regulator of anxiety” (and depression). Interestingly there is a growing consensus that Inflammatory Bowel Disease is associated with anxiety- and depression-related symptoms, and, these psychological symptoms appear to be more prevalent during active disease states. This indicates that imbalances in gut health directly influence and mental well-being.

Gut Brain Axis: IBS

One of the most common theories in the relationship between IBS and mood is that imbalances in the microbiome, that can be caused by numerous factors, may negatively impact the immune system and the health of the gut lining, creating low level systemic inflammation and activation of stress physiology which may then influence emotional wellbeing and behaviour. The below diagram sums this up well.


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J Clin Med. 2018 Jan 3;7(1)

Gut Brain Axis: Autism

There is a wealth of research indicating that imbalances in the microbiome may contribute to autism. I would like to highlight there are numerous contributory factors but I do think it’s safe to say that the gut is a key area to focus upon with a functional medicine approach to improving the condition. The imbalances found in autistic children include imbalances in the microbiome, as well as leaky gut. It is thought that these imbalances influence neurodevelopment by way of the gut brain axis.

A relationship between improved gut health and decrease of symptoms in autism has been reported as well. Studies done to evaluate the gluten-free diets, casein-free diets, pre- and probiotic and multivitamin supplementation have shown promising results. Probiotics have been thought to alleviate the progression of autism and reduce cognitive and behavioural deficits.


I am increasingly a man of simplicity. So general considerations to improve the axis include:

  • A mediterranean diet.
  • Adequate sleep – which needs to include deep sleep – the most restorative kind.
  • Daily activity.
  • Managing our stress levels: This may include incorporating some meditation, tai chi, yoga, breathwork in to our daily routine. Please do not ignore or underestimate what for many is the most important intervention.
  • The cultivation of a healthy emotional state and mindset – practicing gratitude and learning tools from positive psychology.

More personalised recommendations may be considered in the context of an individuals health, lifestyle, health history and functional testing. For example results from a microbiome stool test.


A great gut brain axis book is called The Mind Gut Connection. Another is called The Psychobiotic Revolution.


  • Microbiome-Gut-Brain Axis: Probiotics and Their Association With Depression: click here.
  • The Gut-Brain Axis: The Missing Link in Depression: click here.
  • Gut brain axis: diet microbiota interactions and implications for modulation of anxiety and depression: click here.
  • The Perturbance of Microbiome and Gut-Brain Axis in Autism Spectrum Disorders: click here.
  • Autism and Gut-Brain Axis: Role of Probiotics: click here.
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