Effect of zinc supplementation on tumor necrosis factor-alpha in type2 diabetic patients with metabolic syndrome

Abstract

The purpose of this study was to investigate the effects of zinc supplementation on the levels of plasma zinc, plasma TNF-α, transmembrane TNF-α (tmTNF-α) in peripheral blood mononuclear cells (PBMC), fasting blood sugar (FBS), hemoglobin A1c (HbA1c), triglycerides (TG), total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) in type 2 diabetic patients with metabolic syndrome (MS). Twenty-three type 2 diabetic patients who had MS diagnosed by the International Diabetes Federation criteria were included in the study. They were divided into 2 groups, the zinc group (supplemented with zinc sulfate equivalent to elemental zinc 30 mg/d, n = 10) and the control group (supplemented with placebo equivalent to corn starch 132 mg/d, n = 11) for 8 weeks. At baseline and at week 8, fasting blood samples were collected to determine biochemical parameters. PBMC were isolated for tmTNF-α analysis. Anthropometric parameters and blood pressure were also measured. Furthermore, the patients completed questionnaires about the dietary pattern intake in the past 1 month and 24-hour dietary recall. The results of the study showed that after zinc supplementation for 8 weeks, the plasma zinc levels were significantly increased from the baseline (p < 0.001) and were significantly higher than those in the placebo group (p = 0.001). The FBS levels were significantly reduced from the baseline (p = 0.007) after zinc supplementation; however, there was no significant difference from those in the placebo group. At week 8, the levels of plasma TNF-α, tmTNF-α in PBMC, HbA1c, TG, TC, HDL-C, LDL-C, waist circumference, weight, BMI, and blood pressure in both groups were not significantly changed from baseline. The levels of these parameters were not significantly differences between groups at baseline and week 8. No severe adverse effect of zinc supplementation was found. This study showed that zinc supplementation at the dose of 30 mg/day for 8 weeks offered a therapeutic approach in maintaining plasma zinc and controlling blood sugar levels in type 2 diabetic patients with MS.