Fish Consumption and the Risk of Depression: A Systematic Review and Meta-Analysis of Observational Studies

Background/Objectives: This systematic review and meta-analysis of observational studies aimed to assess the association between fish consumption and the risk of general and pregnancy-related depression, with implications for public health promotion. Methods: We retrieved 5074 articles from PubMed and Embase through November 2023 and included 35 observational studies in the analysis. We synthesized effect estimates as relative risks (RRs) with corresponding 95% confidence intervals (CIs) using a random-effects model. Additional dose–response analyses and stratified subgroup analyses were performed. Results: A significant inverse association was found between fish consumption and depression risk (RR = 0.79, 95% CI: 0.73 to 0.86). A similar association was observed for pregnancy-related depression (RR = 0.78, 95% CI: 0.69–0.89). Stratified analyses showed that only studies with fish intake ≥68.4 g/day demonstrated a statistically significant reduction in depression risk (RR = 0.75, 95% CI: 0.67–0.84), whereas studies with lower intake (<68.4 g/day) showed no significant association (RR = 0.83, 95% CI: 0.69–1.01), suggesting a potential threshold effect. Dose–response analysis further supported a 6% reduction in depression risk per 15 g/day increase in fish intake. Conclusions: This meta-analysis supports fish consumption as a modifiable factor for depression prevention, with ≥68.4 g/day as a possible threshold, potentially informing dietary guidelines and public health strategies.