Association between erythrocyte n-3 polyunsaturated fatty acids and biomarkers of inflammation and oxidative stress in patients with and without depression

Associations between n-3 polyunsaturated fatty acids (PUFAs), inflammation, oxidative stress and the risk of depression have been suggested. We hypothesize that erythrocyte n-3 PUFAs are inversely associated with biomarkers for inflammation and oxidative stress in Koreans with and without depression. Study participants comprised 80 cases diagnosed with depression based on the Center for Epidemiological Studies Depression Scale Korea version (CES-D-K) scores ≥25 and psychiatrist confirmation and 80 age- and sex-matched healthy controls without histories of depression. Depressed patients had lower levels of n-3 PUFAs and higher circulating levels of inducible nitric oxide synthase (iNOS), superoxide dismutase, interferon-γ, and nitrotyrosine compared to the controls. CES-D-K scores and levels of iNOS and tumor necrosis factor (TNF)-α were negatively associated with Omega-3 Index (erythrocyte levels of eicosapentaenoic acid and docosahexaenoic acid) after adjusting for confounding factors. Concentrations of iNOS, TNF-α, thiobarbituric acid reactive substances, and nitrotyrosine were negatively correlated with erythrocyte levels of n-3 PUFAs, but positively with erythrocyte levels of n-6 PUFAs. Erythrocyte levels of n-3 PUFAs were inversely associated with circulating markers of inflammation and oxidative stress in Koreans with and without depression in this case control study. Future randomized controlled trials are needed to determine whether dietary or supplemental n-3 PUFAs can reduce inflammation and oxidative stress, and reduce depressive symptoms in humans.