Do mood disorders start in the gut?

Gone are the days where depression and anxiety where thought to be purely the result of a biochemical imbalance. Over the last decade, it’s become clear that there are multiple factors influencing the pathology behind mood disorders: Environment, diet, genetics, lifestyle and social factors are all at play, influencing not only mental wellbeing, but whole-body health too.

It is a well- researched fact that gut and brain health are inextricably linked. Depression and anxiety are often seen alongside gut conditions such as IBS, IBD, Crohn’s disease and ulcerative colitis, leading some researchers to ask the question, “Which came first?”. While there may not currently be an answer to this question, treating one area often helps to reduce or even eradicate the symptoms of the other. Considering what we know about the importance of the gut in terms of how the microbiome communicates with and supports brain health, this should come as no surprise.

Are mood disorders and food sensivities linked?

Diagnosis of a digestive condition usually brings with it questions regarding food allergies or sensitivities. This is an important factor to consider, as an inflamed gut will not react well to foods that make it more irritated. Irritation or inflammation of the epithelial layer that lines the intestines leads to an opening of the tight junctions between intestinal cells (which otherwise remain closed), causing the condition commonly known as ‘leaky gut’. Other factors such as stress, infection and dysbiosis can also contribute to gut permeability.

As particles of food matter escape into the lymphatic layer below, a cascade of pro-inflammatory events ensues. Inflammatory cytokines (messengers of the immune system) react, alerting the body that there is danger present. These signalling proteins are also able to cross the blood-brain barrier, causing inflammation and disruption to neurotransmitter metabolism (1). A subsequent rise in associated oxidative stress has been proposed as another route by which brain health may be affected, giving rise to symptoms of anxiety and depression.

Research suggests that cytokine activation associated with leaky gut may be strongly linked to the development of neuroinflammation and that this, in turn, could result in the symptoms of depression and/or anxiety.

As opposed to a food allergy, a food sensitivity or intolerance is a delayed reaction following exposure to a certain food, mediated by the immunoglobulin, IgG. Symptoms of such sensitivities include bloating, acid reflux, abdominal pain, headaches and diarrhoea/constipation.

Leaky gut is associated with IgG mediated sensitivities, either as a cause or direct result of their presence. It is well known that zonulin, a protein that influences intestinal permeability, is secreted in some people on exposure to gluten – in particular, those that suffer from Coeliac disease.

Heal the gut, heal the brain

The term given to inflammation arising within the brain is neuroinflammation. Research suggests that cytokine activation associated with leaky gut may be strongly linked to the development of neuroinflammation and that this in turn could result in the symptoms of depression and/or anxiety. There are various theories as to whether inflammation is a cause or consequence of mood disorders, but either way, it must be considered a contributing factor (2).

While mood disorders have a complex pathophysiology, addressing gut health is an important component of providing care for those who suffer from them. Ignoring the gut would be unwise, as the weight of evidence is stacked up in support of the gut-brain connection. It must also be taken into consideration that the maintenance of a healthy gut and microbiome have flow-on effects to ALL areas of the body.

Assessing for the presence of a food sensitivity can be done in two ways:

  • Pathology testing for the presence of an IgG mediated sensitivity
  • Eliminating suspect foods from the diet for a period of at least 2 weeks, then reintroducing each food one by one. A journal is kept to monitor the presence of symptoms.

Once sensitivities have been assessed, generally all foods implicated should be removed from the diet. Then, an anti-inflammatory gut healing protocol should be commenced. It’s not uncommon to find with time, some foods may be reintroduced, however this should only be done following re-testing to ensure that the sensitivity is in longer present.

Fostering a healthy microbiome is key to supporting gut-brain health. Eating a variety of fruits and vegetables, lean meat and fish, nuts, seeds, healthy oils, and reducing refined and processed foods is essential to keep our intestinal bacteria well fed. Diversity is key! Research shows that a diverse diet gives rise to a diverse microbiome – which translates to a happier, healthier gut, brain and body (3).

If you’d like more information on natural solutions for mental health, feel free to get in contact.


(1) Karakuła-Juchnowicz, H., Szachta, P., Opolska, A., Morylowska-Topolska, J., Gałęcka, M., Juchnowicz, D., … Lasik, Z. (2017). The role of IgG hypersensitivity in the pathogenesis and therapy of depressive disorders. Nutritional Neuroscience, 20(2), 110–118. https://doi.org/10.1179/1476830514Y.0000000158

(2) Jeon, S. W., & Kim, Y. K. (2016). Neuroinflammation and cytokine abnormality in major depression: Cause or consequence in that illness?. World journal of psychiatry6(3), 283–293. doi:10.5498/wjp.v6.i3.283

(3) Duda-Chodak, A., Tarko, T., Satora, P., & Sroka, P. (2015). Interaction of dietary compounds, especially polyphenols, with the intestinal microbiota: a review. European journal of nutrition54(3), 325–341. doi:10.1007/s00394-015-0852-y

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