Elsevier

Journal of Affective Disorders

Volume 150, Issue 2, 5 September 2013, Pages 682-685
Journal of Affective Disorders

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

https://doi.org/10.1016/j.jad.2013.03.027Get rights and content

Abstract

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-d food record. Baseline depression severity was recorded with the Human Population Laboratory Depression Scale. In the prospective setting, 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 to 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.

Introduction

Zinc is an immunomodulatory trace element that has been suggested to be potentially beneficial in the augmentation of antidepressant therapy (Lai et al., 2012). In addition to immunomodulatory effects, zinc also modulates the functions of the hypothalamus–pituitary–adrenal (HPA) axis, as well as serotonergic and NMDA receptor activity in the central nervous system (Huang, 1997, Szewczyk et al., 2009, Szewczyk et al., 2011, Takeda and Tamano, 2009). The hippocampus and amygdala, which are mood-regulation-related brain areas known to be altered in depression, also have large numbers of zinc-containing neurons (Brown and Dyck, 2004).

Cross-sectional general population studies have suggested that a low dietary zinc intake is associated with depression in women (Jacka et al., 2012, Maserejian et al., 2012), but not in men (Maserejian et al., 2012). An association between depression and zinc intake has also been observed in mixed-gender samples of postgraduate students (Yary and Aazami, 2012) and elderly individuals (Marcellini et al., 2006).

To date, only two large population-based studies have examined the cross-sectional association between dietary zinc intake and depression (Jacka et al., 2012, Maserejian et al., 2012). Furthermore, there have been no prospective studies focusing on the association between the incidence of depression and zinc intake. The objective of this study was to examine the impact of dietary zinc intake on the risk of incident depression in 2317 Finnish middle-aged men.

Section snippets

Study setting and participants

The Kuopio Ischemic Heart Disease Risk Factor Study is a population-based study focusing on risk factors for ischemic heart disease and other outcomes among middle-aged men in the Kuopio region of eastern Finland (Salonen, 1988). A total of 2682 participants aged 42–60 years were recruited for the baseline examination, which occurred between March 1984 and December 1989. Data were incomplete for 82 participants, and complete data were therefore available for 2600 men. All participants provided

Results

A total of 60 (2.7%) men were discharged with a depression diagnosis during the follow-up. Altogether, 2189 (94.5%) of the participants reached the Finnish zinc RDI for men (≥9 mg/d; National Nutrition Council, 2005).

Discussion

To the best of our knowledge, this was the first prospective study examining the association between dietary zinc and the risk of depression. Dietary zinc intake was not associated with an increased risk of depression diagnosed upon hospitalization discharge in a 20-year follow-up in men, regardless of adjustments for age, dietary supplement use and several lifestyle factors.

Our findings indicated a modest but significant inverse correlation between dietary zinc intake and depression in men in

Conflict of interest

None declared.

Role of funding source

The authors conducted this study as part of their work, without external funding. Thus, the funding had no role in study design; in the collection, analysis and interpretation of data; in the writing of the report; and in the decision to submit the paper for publication.

Acknowledgments

The authors thank the personnel of the former Research Institute of Public Health for their valuable contribution to this study.

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