Vitamin D Deficiency Mediates the Relationship between Dietary Patterns and Depression: A Case- Control Study

Depression, one of the most common psychological conditions, is a major contributor to disability-adjusted life years lost in the world. Due tothe complex interactions between nutrients and foods, nutritional epidemiologists have suggested the use of dietary pattern approach in investigating diet-disease relations. Therefore, the aim of present study was to identify dietary patterns in relation with depression,also investigating if some biomarkers mediated this association. Materials and Methods: In this individually matched case-control observational study, 330 depressed and healthy subjects were recruited; Patients were diagnosed by psychiatrists as majordepressive disorder, using DSM-IV. Dietary intakes of the subjects in the last 12 months were assessed using a semi-quantitative food frequency questionnaire. Some of all depressed and healthy individuals were chosen randomly for the measurement of serum level 25(OH)D, zinc, magnesium and total Antioxidant Capacity (TAC). While evaluating the relationship between dietary patterns and depression, the biomarkers are considered as potential mediator variable. Results: we observed a negative significant relationship between depression and serum vitamin D, whereas there were no significant association between depression and serum level TAC, serum zinc and magnesium. We also identified two healthy and unhealthy dietary patterns led to significantly lower and higher odds for depression, respectively. In mediated analysis, healthy dietary pattern is related to decreased depression via increasing serum vitamin D; while, the unhealthy dietary patternis related to increased depression via decreasing serum vitamin D. Conclusion: Vitamin D deficiency mediates the relationship between Dietary Patterns and Depression, but further prospective studies are required