The Mediterranean dietary pattern and depression risk: a systematic review

Background: Depression is a major global health burden and psychiatry requires evidence-based primary prevention and treatment strategies. Evidence suggests that certain dietary patterns, in particular, components of the Mediterranean diet, possess key biological factors associated with abating depressive risk and disease progression. We sought to evaluate the existing evidence regarding the association between the Mediterranean diet and depressive symptoms by conducting a systematic review. Methods: A search of published studies was conducted using the computer databases Medline, Embase, PsychINFO, Scopus and Google Scholar, for articles in the English language published from inception to April 2018. The search strategy applied the following subject headings and keywords: “Mediterranean diet” OR Mediterranean* AND “Major depressive disorder” OR Depress* OR “Negative mood” OR Mood. The NIH quality assessment tool was implemented by reviewers to determine study quality. Results: Results from twenty observational studies and six intervention trials were qualitatively examined. The majority (85%) of observational studies support the evidence that the Mediterranean dietary pattern is associated with reductions in depressive incidence and all intervention studies echoed these findings. Limitations: Methodological disparity in Mediterranean style diets limited comparisons but were overcome by specifying inclusion criteria and compressive appraisal of the data. Conclusions: Modifying diet provides a potential treatment for depression which procures few side effects, lessens disease progression and demonstrates a cost-effective measure that can be implemented globally. Present research has found that more objective measures are necessary to define the Mediterranean diet and highlights the need for longitudinal studies and clinical trials for future research.