The Relationship Between a Leaky Gut and Depression

Inside our digestive tract our intestinal lining comprises a continuous layer of cells that form tight junctions. When working properly this lining is permeable enough to allow the absorption of water and nutrients. However, the intestinal lining also needs to be tight enough to prevent harmful substances like bacteria, toxins, and undigested food particles from entering the bloodstream.

Leaky gut, or ‘intestinal hyperpermeability’ is a condition where the lining of the small intestine become damaged, causing undigested food particles, toxic waste products and bacteria to ‘leak’ through the intestines and enter the bloodstream. A leaky gut can be caused by certain medications, especially antibiotics, an unhealthy diet, eating foods you are intolerant/allergic to, excess alcohol intake, smoking, and even high stress.

Leaky gut is associated with most digestive disorders including coeliac disease, inflammatory bowel disorder, and irritable bowel syndrome. There is also increasing research confirming a relationship between a leaky gut and mental health. For example, increased intestinal permeability has been confirmed in several studies in adults with depression [1] and schizophrenia [2]. A leaky gut was also identified in teenagers with depression, with higher levels associated with greater severity of depressive symptoms [3].

A leaky gut can be problematic as it is a major driver of inflammation. Excess inflammation can have a negative impact on our hormones. In particular, it can reduce levels of the mood-lifting neurotransmitter serotonin. Low levels of serotonin are implicated in depression. Excess inflammation can also increase levels of cortisol (our primary stress hormone) and increase free radical activity. Excess free radical production can damage the brain over time.

While further research is required, treating a leaky gut could be a potential treatment for depression and other mental health problems. This is supported by increasing research confirming the strong bi-directional relationship between the brain and the gut. The best way to treat a leaky gut is to utilise an integrative approach including improving diet quality, reducing stress, avoiding food intolerances, avoiding unnecessary medications, reducing alcohol and nicotine use, and utilising gut-healing herbs and spices.

References

1. Slyepchenko A1, et al. Gut Microbiota, Bacterial Translocation, and Interactions with Diet: Pathophysiological Links between Major Depressive Disorder and Non-Communicable Medical Comorbidities. Psychother Psychosom. 2017;86(1):31-46.
2. Maes M, et al. In Schizophrenia, Increased Plasma IgM/IgA Responses to Gut Commensal Bacteria Are Associated with Negative Symptoms, Neurocognitive Impairments, and the Deficit Phenotype. Neurotox Res. 2018 Dec 15. 
3. Calarge CA, et al. Gut permeability and depressive symptom severity in unmedicated adolescents. J Affect Disord. 2018 Dec 26;246:586-594.