Dietary zinc intake and the risk of depression in middle-aged men: A 20-year prospective follow-up study

Background: Zinc is an immunomodulatory trace element suggested to be beneficial in the augmentation of antidepressant therapy. Cross-sectional studies have also suggested an association between low dietary zinc and depression. This study examined the association between dietary zinc intake and depression in a prospective setting in initially depression-free men during a 20 year follow-up. Methods: The study formed a part of the population based Kuopio Ischemic Heart Disease Risk Factor (KIHD) Study, and comprised 2317 Finnish men aged 42-61 years. Zinc intake was assessed at baseline by a 4-(1 food record. Baseline depression severity was recorded with the Human Population Laboratory Depression Scale. In the prospective selling, depression was defined as having received a hospital discharge diagnosis of unipolar depressive disorder. Individuals who at baseline had elevated depressive symptoms were excluded (n=283). Results: Altogether, 60 (2.7%) individuals received a hospital discharge diagnosis of depression during the 20 year follow-up. In Cox regression analysis adjusted for age, baseline depression severity, smoking, alcohol use, physical exercise and the use of dietary supplements, belonging W the lowest tertile of energy-adjusted zinc intake was not associated with an increased depression risk (RR 1.06, 95% CI 0.59-1.90). Limitations: These observations may not be generalizable to women, or to individuals with a depression level not warranting hospitalization. Conclusions: Our findings suggest that a low dietary zinc intake may not longitudinally precede depression in men. Dietary zinc intake may not have relevance for the prevention of depression in middle-aged men with a sufficient dietary zinc intake. (C) 2013 Elsevier B.V. All rights reserved