High levels of plasma selenium are associated with metabolic syndrome and elevated fasting plasma glucose in a Chinese population: A case-control study

Background: Selenium is important for human health and involved in various metabolic processes. Deficiency of selenium associates with increased risk for cancer and cardiovascular diseases. There has been an increase use of selenium supplements for the treatment of autoimmune thyroid conditions. However, the potential biological effects of selenium overload arouse the public concern. The aim of this study was to investigate the associations of plasma selenium concentrations of adults with metabolic syndrome (MS) in Chinese population. Methods: A matched case-control study including 204 metabolic syndrome patients and 204 healthy controls was conducted in 2012. The MS cases were defined according to the criteria of Chinese Diabetes Society (CDS). Healthy controls without abnormality of metabolic components were matched with cases in age, gender and region. Plasma concentrations of selenium were determined by graphite furnace atomic absorption spectrometry (GFAAS). Fasting plasma glucose (FPG), total cholesterol (TC), triglycerides (TG), high density lipoprotein cholesterol (HDL), and low density lipoprotein cholesterol (LDL) were detected by automatic biochemical analyzer. Results: The median levels of plasma selenium in MS group were 146.3 (107.3-199.4) mu g/L, which were significantly higher than that in the control group (127.4: 95.7-176.0) mu g/L; Plasma levels of selenium were related to the risk of MS in dose-response manner. Risk of MS was significantly higher in subjects with plasma selenium in the highest tertile (T3: >= 176.0 mu g/L) compared to those in the lowest tertile (T1: <95.7 mu g/L) [odds ratio (OR) = 2.416 (95% CI: 1.289-4.526)]. The plasma levels of selenium were positively correlated with fasting plasma glucose (FPG) (r(s) = 0.268, P < 0.001). Plasma selenium at the median (T2: 95.7-176.0 mu g/L) or upper tertile (T3: >= 176.0 mu g/L) was associated with increased risk of elevated FPG (defined by FPG >= 6.1 mmol/L) as compared with the lowest tertile (T1: <= 95.7 mu g/L) [T2 vs. T1, OR = 3.487 (1.738-6.996); T3 vs. T1, OR = 6.245 (3.005-12.981)]. Conclusions: Higher levels of plasma selenium might increase the risk of metabolic syndrome and elevated fasting plasma glucose. Selenium supplements should be used with prudence for CVD and cancer prevention. (C) 2015 Elsevier GmbH. All rights reserved.