Cross-sectional association of seafood consumption, polyunsaturated fatty acids and depressive symptoms in two Torres Strait communities

Background Dietary intake of long-chain omega 3 (n-3) polyunsaturated fatty acids (LCPUFA) represents a putative modifiable risk factor for depression, and a high ratio of omega 6 (n-6) to n-3 LCPUFA is frequently observed in patients with major depressive disorder. Recent reports suggest that the availability of fish and seafood may be associated with lower depression rates. The aim of this study was to investigate associations of fish consumption and LCPUFA levels with depressive symptoms. Methods Participants for this cross-sectional study (n=206) were recruited at a community screening programme in two Torres Strait Islander communities (Mer and Waiben). Depressive symptoms were assessed with the adapted Patient Health Questionnaire-9 (aPHQ-9) and diet with a structured questionnaire. LCPUFA concentrations were measured with a capillary dried blood spot system (PUFAcoat). Logistic and quantile regression modelling was used to test the relationship between seafood consumption, membrane LCPUFAs and depression scores. Results A higher blood n-6/3 LCPUFA ratio was associated with moderate/severe depression scores across both study sites (OR=1.59 (95%CI 1.09-2.34), P = .017). Seafood consumption was higher and the proportion of participants with aPHQ-9 scores above the cut-off for depression was lower on Mer (n = 100) compared with Waiben (n = 106). Higher seafood consumption was associated with lower depression scores on Waiben (B = -0.57 (95%CI -0.98 - -0.16), P = .006) but not on Mer. Conclusions Our findings support an association of n-3 LCPUFA from natural sources with depressive symptoms. The availability of fresh seafood in the local diet may represent a protective factor for depression in this setting.