Dietary patterns and adult mental health: a systematic review of observational studies

Diet is a factor related to individuals' lifestyle that has been widely studied in relation to its association with common mental disorders (depression and anxiety). However, the relationship between dietary patterns and these mental health conditions has not been systematically reviewed. The purpose of the present study was to systematically review and synthesize published research on associations between common mental disorders and dietary patterns in adults. The present systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Six electronic databases were searched through 2024, without restrictions regarding the initial year of publication and the selected articles were imported into Rayyan Web® software. Two reviewers independently selected and extracted data, with disagreements resolved by a third reviewer. Methodological quality and risk of bias were assessed using Joanna Briggs Institute tools. The results were presented in tables, text, and forest plots. The results were presented in tables, text, and forest plots. A total of 26 studies were included: 20 examined depression, 5 examined anxiety, and one assessed both conditions. The number of participants ranged from 135 to 14,541. The results of this review suggest an inverse association between healthy dietary patterns and common mental disorders (especially for depression, which had the largest number of articles available in the literature ( n = 20). Evidence regarding anxiety was limited and inconsistent due to the small number of available studies. The association with unhealthy dietary patterns is still unclear, due to the high heterogeneity of the results found in the studies. Mixed and mixed-alcoholic patterns were also not consistently associated with the common mental disorders analyzed. Healthy dietary patterns may be associated, particularly, with a lower frequency of depression. Thus, although the results reinforce the importance of diet as a key component of mental health promotion strategies, more robust future studies are needed to better understand these associations.