As mentioned previously, there is now repeated evidence to demonstrate that the Mediterranean diet may help improve symptoms of depression. One of the hypotheses as to why this is possible is the ability for the Mediterranean diet to reduce levels of inflammation. Research is continually demonstrating that inflammation plays a major role in the pathogenesis of mental health conditions, including depression, anxiety, and schizophrenia.
Many studies show that depression is associated with elevated levels of a number of biomarkers that indicate inflammation including C-reactive protein (CRP) and IL-6. (3) These inflammatory metabolites are able to access the brain and disrupt the pathophysiology of depression, including neurotransmitter metabolism. This activation of inflammatory pathways is believed to contribute to oxidative stress, which further creates inflammation in the brain called neuroinflammation.
Another potential mechanism in which food exerts its effects on our mental health is through our gut microbiota, due to the gut-brain axis. There are millions of diverse micro-organisms living inside of our guts, which influence many aspects of our health, including: immune function, mental functioning, and cardiovascular health.
The most direct influence on our gut microbiota is our diet, which is responsible for up to 60% of the bacteria variation. Dysbiosis, or an alteration in the composition and environment of our gut microbiota, can lead to increased intestinal permeability. This can allows contents, such as bacterial metabolites from the gut, to cross into our blood circulation—otherwise known as leaky gut (which is not yet a widely recognized medical condition, but often discussed in the functional medicine community). This could lead to further inflammation in the body as these inflammatory products are circulated, contributing to neuroinflammation.