Depression is a common mental disorder that causes symptoms like persistent sadness, irritability, decreased energy, and loss of pleasure in daily activities. Depression is one of the most common mental disorders – it is estimated that roughly 5% of adults suffer from depression and can lead to suicide – the magnitude of depression has impelled scientists to identify the root cause of this disorder and any possible treatment approaches (WHO, 2021). Currently, the cause of depression is unknown. Scientists have accepted that one possible cause of depression is an imbalance of brain chemicals, known as neurotransmitters. To combat this imbalance, researchers have formulated a drug, known as SSRIs, that aims to increase the level of serotonin to alleviate depressive symptoms. Although antidepressants have been an effective treatment route for some, research has suggested that nearly half of depressed patients did not experience a reduction in symptoms after two courses of antidepressant treatment (Wiles et al., 2014). Therefore, one can surmise that the neurotransmitter hypothesis does not account for all cases of depression and other potential causes for depression should be considered. Researchers have also hypothesized that depression could be caused by over inflammation in the brain. Numerous studies have concluded that there is an association between Major Depressive Disorder and persistent low grade central inflammatory activation (Park et al., 2018). For example, individuals that are at a high risk for depression (categorized by early life trauma), show increased inflammatory responses to stressors compared to low risk individuals (Miller and Raison, 2016). The stressor in question could be something as simple as giving a presentation to a group of experts; in this case, the body initiates an immune response against a threat to self esteem instead of a pathogen. The directionality of this correlation has also been examined in previous research; one study deduced that increasing the inflammatory potential of diet leads to depressive symptoms in female adolescents. Since it has been established that over inflammation in the brain can lead to depression, experts have speculated that an anti-inflammatory diet could reduce current depressive symptoms or act as a protective measure against the development of depressive symptoms.
The hypothesis that diet can act as an antidepressant seems too simple. Today, individuals with depression are advised to undergo talk therapy or begin a course of antidepressants. However, it’s important to recognize how our modernized society could play a key role in the prevalence of depression. Increasing evidence suggests that disruptions in mankind’s relationship with a variety of non-lethal immunoregulatory microorganisms and parasites – that were omnipresent in the environment humans evolved in – induces the widespread immune dysregulation that is associated with autoimmune and inflammatory diseases (Miller and Raison, 2016). Through biological processes, these microorganisms reduce inflammation and suppress effector immune cells. As our society becomes more sanitized, especially in a pandemic, modern humans are bereft of this immunoregulatory input from microorganisms. Especially with the high-comorbidity between depression and autoimmune diseases, I believe a possible explanation of the inflammatory properties associated with depression are a result of our strained relationship with microorganisms (Miller and Raison, 2016).
Since research has showcased that a diet rich in anti-inflammatory components may be protective against depression, here is a list of foods that possess anti-inflammatory compounds (Brackett, 2021):
- Olive oil
- Green tea
Brackett, A. (2021). The 13 Most Anti-Inflammatory Foods You Can Eat. Healthline. Retrieved April 26, 2022, from https://www.healthline.com/nutrition/13-anti-inflammatory-foods
Miller, A., Raison, C. The role of inflammation in depression: from evolutionary imperative to modern treatment target. Nat Rev Immunol 16, 22–34 (2016). https://doi.org/10.1038/nri.2015.5
Caroline Park, Elisa Brietzke, Joshua D. Rosenblat, et al. Probiotics for the treatment of depressive symptoms: An anti-inflammatory mechanism?. Brain, Behavior, and Immunity, Volume 73. 2018. Pages 115-124
Wiles N, Thomas L, Abel A, et al. Clinical effectiveness and cost-effectiveness of cognitive behavioural therapy as an adjunct to pharmacotherapy for treatment-resistant depression in primary care: the CoBalT randomised controlled trial. Southampton (UK): NIHR Journals Library; 2014 May. (Health Technology Assessment, No. 18.31.) Chapter 8, The prevalence of treatment-resistant depression in primary care. Available from: https://www.ncbi.nlm.nih.gov/books/NBK261988/
Depression. (2021, September 13). WHO | World Health Organization. Retrieved April 26, 2022, from https://www.who.int/news-room/fact-sheets/detail/depression