Inflammation and Mood

Most of us have experienced flat moods, irritability, sadness, fatigue and brain fog. These symptoms are often referred to as depression, but there is much that we don’t understand regarding mood disorders. However, thankfully there is now more attention focused on mental health and the underlying causes of some pathologies of the mind.

An important study in this area may help us to understand the link between gut permeability, inflammation and depression. 1 Researchers examined the effect of gut permeability on 41 girls aged 12-17 years.

Depression was measured using a CDRS-R rating scale which assesses severity, and also change in depression. Gut permeability-  or leaky gut, as we commonly call it, was measured using the lactulose mannitol ratio (LMR), which accesses the amount of lactulose and mannitol that passes through the gut lining after overnight fasting. This gives a good measure of how leaky the gut is.  Inflammation levels were also measured as we now know that a leaky gut results in high levels of systemic inflammation.

The results of the study are interesting to say the least, and support the hypothesis that mood disorders are linked with gut permeability. It was reported that the leakier the gut in the sample of girls, the more severe the depression. And the higher the levels of inflammation, the more severe the depression.

So what are the mechanisms behind this? The immune system plays an important role in the manifestation of depressive symptoms, and of interest most of our immune system is actually located in the gut. The lining of the gut is a barrier and if this barrier is compromised then inflammation will follow.

Inflammation is the body’s defence mechanism to deal with injury or assault. We live in a toxic world and so we are under constant assault in modern Western countries. Stress to the body can come anything from anxiety, to pesticides on our food, to stress, to processed, sugary foods. These all cause the body a level of stress and produce inflammation.

When the body is stressed a leaky gut can follow as the junctions between the cells in the gut become less effective. This allows toxins that normally stay in the intestine to leak into the bloodstream promoting an immune response. The inflammatory cascade is ongoing and so is referred to as chronic inflammation, and inflammation in the body can extend to the brain 2.

As the above mentioned study highlighted, inflammation is associated with a leaky gut and both are linked with severe depressive symptoms. If we stop approaching mood disorders as genetic predispositions, or a chemical imbalance in the brain, and start approaching them as inflammatory disorders, we may utilise treatments that result in remission, as opposed to merely band -aiding the symptoms.

Chadi A. Calarge, Sridevi Devaraj, Robert J. Shulman. (2019). Gut permeability and depressive symptom severity in unmedicated adolescents, Journal of Affective Disorders,

246, pp.586-594