Serum long chain omega-3 fatty acids and depression among adults in the United States: An analysis of NHANES 2011–2012

Abstract

• Adults with higher omega-3 fatty acid levels had less severe depressive symptoms. • Adults with higher EPA reported less impact of depressive symptoms on daily life. • Our results are one of the few in a population representative of adults in the US. Few studies have examined biomarkers of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) with depression, that are less prone to error than self-reported intake. We aimed to determine associations between serum EPA, DHA and the sum of long chain (LC) omega-3 fatty acids with depression in the National Health and Nutrition Examination Survey (NHANES) 2011–2012 cycle. Fatty acids were expressed as a % of total fatty acids. Depression was assessed by the Patient Health Questionnaire (PHQ)-9 and categorized as minimal (score 0–4, reference), mild (5–9), moderate (10–14), and moderately severe to severe depression (15–27). The impact of depressive symptoms was also assessed. Associations were estimated by regression with adjustment for sociodemographic covariates. Among 1186 adults, 77.9% reported minimal depressive symptoms, while 14.3%, 5.06% and 2.75% of participants had mild, moderate and moderately severe to severe depression. Higher serum EPA, DHA and LC omega-3 fatty acids were associated with lower relative risk (RR) of moderately severe to severe depression. For example, EPA: RR=0.30, SE 0.11, p = 0.005. Participants with higher serum EPA, were less likely to report very or extreme difficulty with daily life tasks due to depressive symptoms (RR=0.39, SE 0.17, p = 0.05). The temporal nature of relationships cannot be determined due to the cross-sectional design. Higher serum omega-3 fatty acids were associated with lower risk of moderately severe to severe depression while serum EPA was positively associated with ability to perform daily life tasks. Collectively, this shows the importance of EPA and DHA for treating depression.