A pro-inflammatory diet including fast food, processed food, and refined sugar is associated with a 40% increased risk of depression according to a meta-analysis of 11 studies.

It is always difficult to establish causality with associative studies. With respect to inflammation and depression, there have been some studies establishing causality. For example, healthy individuals injected with proinflammatory cytokines exhibit depressive symptoms compared to those injected with a placebo.

Moreover, inflammation can be clinically monitored by well-known biomarkers for systemic inflammation, making it amenable to potentially tracking therapeutic success: the risk of major depression has been shown to increase by 44% for each standard deviation increase in log c-reactive protein.

To learn more about the role inflammation plays in depression, check out the animated video we put together on the role inflammation plays in depression.