Elsevier

Nutrition

Volume 37, May 2017, Pages 43-47
Nutrition

Applied nutritional investigation
Association between serum zinc and later development of metabolic syndrome in middle aged and older men: The Kuopio Ischaemic Heart Disease Risk Factor Study

https://doi.org/10.1016/j.nut.2016.09.004Get rights and content

Highlights

  • Serum zinc was directly associated with the incidence of metabolic syndrome.

  • Serum zinc was inversely associated with high-density lipoprotein.

  • Serum zinc was directly associated with hypertension.

  • Serum zinc was directly associated with waist circumference.

Abstract

Objective

The aim of this study was to investigate associations of serum zinc with incident metabolic syndrome and its components in middle-aged and older Finnish men.

Methods

An 11-y prospective follow-up study conducted among 683 men from the Kuopio Ischaemic Heart Disease Risk Factor Study who were 42 to 60 y old at baseline in 1984 to 1989. The main outcome was incident metabolic syndrome, defined by the National Cholesterol Education Program (NCEP) criteria. Other outcomes were the individual components of the NCEP metabolic syndrome: Fasting blood glucose, serum triacylglycerols, serum high-density lipoprotein (HDL) cholesterol, hypertension, and waist circumference.

Results

During the average follow-up of 11 y, 139 men (20.4%) developed metabolic syndrome. Those in the highest tertile of serum zinc had 84% higher risk (95% confidence interval 12 to 201%, P trend across tertiles = 0.015) to develop metabolic syndrome compared with those in the lowest tertile, after adjustment for several potential confounders. The association between serum zinc and incident metabolic syndrome was attenuated by adjustment for waist circumference, serum HDL cholesterol, or hypertension. Serum zinc was also directly associated with higher waist circumference and hypertension and inversely associated with HDL cholesterol at the 11 y examinations.

Conclusions

We found a direct association between serum zinc and incidence of metabolic syndrome in middle-aged and older eastern Finnish men. Further studies are warranted to explore the mechanisms.

Introduction

Metabolic syndrome is characterized by hypertension, excess abdominal fat, and dyslipidemia, all of which have been shown to be involved in the development of a number of chronic diseases, including type 2 diabetes, coronary heart disease, and stroke. Besides the genetic factors, which may have an important role in predisposition to cardiometabolic syndrome [1], unhealthy lifestyle behaviors such as smoking and adherence to a poor diet are implicated in the development of metabolic syndrome [2], [3]. Zinc plays a role in the insulin homeostasis including the synthesis, storage, and secretion of insulin [4], [5].

Insulin resistance has been suggested to play a noteworthy role in the pathogenesis of metabolic syndrome [6], and some evidence suggests a direct association between serum zinc and insulin resistance [7]. The information about the association of zinc with insulin resistance, however, is scarce. Recent cross-sectional studies have reported that higher serum zinc concentration may be a risk factor for metabolic syndrome [8], [9]. Nevertheless, the causality and mechanisms are uncertain because of the cross-sectional study design.

To our knowledge, no prospective study has been conducted of the relation of serum zinc with development of metabolic syndrome. Due to limited research data, more studies are clearly needed. The aim of this prospective study was to assess the relation of serum zinc with metabolic syndrome and its components, which includes waist circumference, fasting blood glucose, serum high-density lipoprotein (HDL) cholesterol, triacylglycerols, and hypertension after 11 y of follow-up among middle-aged and older Finnish men.

Section snippets

Study population

The Kuopio Ischaemic Heart Disease Risk Factor Study (KIHD) was designed to investigate risk factors for cardiovascular disease, atherosclerosis, and related outcomes in a population-based, randomly selected sample of men from Eastern Finland [10]. The baseline examinations were carried out from 1984 to 1989. A total of 2682 men aged 42, 48, 54, or 60 y at baseline (82.9% of those eligible) were recruited in two cohorts (Fig. 1). The first cohort consisted of 1166 men aged 54 y, enrolled from

Results

Table 1 shows the baseline characteristics of the study participants free of type 2 diabetes and metabolic syndrome based on the tertiles of serum zinc. Men with higher serum zinc were younger, smoked less, and had a lower alcohol consumption and HOMA of insulin sensitivity. Higher serum zinc concentration was also associated with higher education, waist circumference, BMI, total cholesterol, and low-density lipoprotein (LDL) and very-low-density lipoprotein (VLDL) cholesterol and

Discussion

The present study shows a direct association between higher serum zinc concentration and increased risk of incident metabolic syndrome in middle-aged and older men. Serum zinc was also directly associated with higher waist circumference and hypertension and inversely associated with HDL cholesterol at the 11 y examinations. In addition, adjusting for the components of metabolic syndrome at the 11-y follow-up attenuated the associations between serum zinc and risk of metabolic syndrome, which

Conclusion

Overall, we found a direct association between higher serum zinc and incidence of metabolic syndrome and three of its components, increased waist circumference, hypertension, and low serum HDL cholesterol, in middle-aged and older men from Eastern Finland. Further prospective studies in other study populations are warranted to confirm our results and to explore the mechanisms.

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    We thank all participants and other staff members for encouraging and supporting this study. We wish to express our sincerest appreciation to Jalmari and Rauha Ahokas Foundation, Centre for International Mobility (CIMO) Fellowship (TM-14-9374) and University of Eastern Finland for supporting this research. It should be noted that the funding agencies had no role in the collection, analysis or interpretation of data neither in writing of the manuscript.

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