Dietary selenium and major depression: a nested case-control study

Objectives and methods: Alterations in redox biology are established in depression; however, there are no prospective epidemiological data on redox-active selenium in depression. We aimed to determine if low levels of dietary selenium are associated with an increased risk for . de novo major depressive disorder (MDD). In this nested case-control study, women aged 20 years or more were identified from a randomly selected cohort being followed prospectively for the Geelong Osteoporosis Study. Cases were individuals with incident MDD, identified using the Structured Clinical Interview for DSM-IV-TR (SCID-I/NP); controls had no such history. Dietary selenium intake was measured using a food frequency questionnaire at baseline, together with anthropometric and lifestyle measures. Results: Eighteen women who developed . de novo MDD were classified as cases; there were 298 controls. Low dietary selenium intakes increased the likelihood of developing MDD; OR 2.74 (95%CI 0.95-7.89). After adjusting for age and SES, compared with a high selenium intake, a low intake (<8.9. μg/MJ/day) was associated with an approximate trebling of the likelihood for developing . de novo MDD; OR 2.95 (95%CI 1.00-8.72). Smoking, alcohol consumption and physical activity did not confound the association. Conclusion: These data suggest that lower dietary selenium intakes are associated with an increased risk of subsequent . de novo MDD. We propose that selenium's function as an antioxidant, and as a constituent of selenoproteins that are important in redox homeostasis, warrants further investigation as a risk factor for depression, and suggest a potentially novel modifiable factor in the primary prevention and management of depression. © 2012 Elsevier Ltd.