The purpose of the present meta-analysis was to evaluate the association between the inflammatory potential of diet, determined by the dietary inflammatory index (DII®) score, and depression.

Systematic review and meta-analysis.

A comprehensive literature search was conducted in PubMed, Web of Science and EMBASE databases up to August 2018. All observational studies that examined the association of the DII score with depression/depressive symptoms were included.

Four prospective cohorts and two cross-sectional studies enrolling a total of 49 584 subjects.

Overall, individuals in the highest DII v. the lowest DII category had a 23 % higher risk of depression (risk ratio (RR)=1·23; 95 % CI 1·12, 1·35). When stratified by study design, the pooled RR was 1·25 (95 % CI 1·12, 1·40) for the prospective cohort studies and 1·16 (95 % CI 0·96, 1·41) for the cross-sectional studies. Gender-specific analysis showed that this association was observed in women (RR=1·25; 95 % CI 1·09, 1·42) but was not statistically significant in men (RR=1·15; 95 % CI 0·83, 1·59).

The meta-analysis suggests that pro-inflammatory diet estimated by a higher DII score is independently associated with an increased risk of depression, particularly in women. However, more well-designed studies are needed to evaluate whether an anti-inflammatory diet can reduce the risk of depression.