[Association between plasma selenium and the risk of impaired glucose regulation]

Association Between Selenium Level in Blood and Glycolipid Metabolism in Residents of Enshi Prefecture, China

The present study aimed to detect selenium (Se) levels in the blood of Enshi Prefecture residents in China and investigate the relationship between blood Se levels and glucose or lipid metabolism disorder. A cross-sectional study was conducted, and 1876 subjects were selected through cluster random sampling from Enshi Prefecture using a questionnaire survey, physical examinations, and biochemical blood tests. The mean blood Se level in the overall population was 0.128 ± 0.178 μg/mL. Se exhibits a "U"-shaped curve on the serum fasting plasma glucose (FPG) of the total samples, that is, when the blood Se is more than 0.131 μg/mL or less than 0.062 μg/mL, the FPG increases significantly. A significant negative correlation was demonstrated between the FPG levels of the 4-17-year-old age group and different blood Se levels (P < 0.001). No significant correlation was demonstrated between the serum triglyceride (TG) and blood Se levels. However, a positive correlation was demonstrated between blood Se and serum total cholesterol (TC) levels and the incidence of high cholesterol in the total population (P < 0.001). The odds ratio and related 95% confidence interval for the incidence of high cholesterol between the highest (≥ 0.133 μg/mL) and lowest blood Se (< 0.064 μg/mL) levels was 2.64 and 1.48-4.79, respectively. The results of this study are very important for the safety scope and risk-benefit assessment of Se in the human; however, further investigation with a larger sample size is required.

Changes in Plasma Fatty Acids, Free Amino Acids, Antioxidant Defense, and Physiological Stress by Oleuropein Supplementation in Pigs Prior to Slaughter

Olive tree leaves are characterized for having not only a potent antioxidant power but also effects on glucose and lipid metabolism. The impact of the individual oleuropein (OLE), vitamin E + Se (VE), or a combined supplementation of oleuropein, vitamin E, and selenium (VEOLE) was evaluated on pig plasma metabolites under fasting prior to slaughter. VEOLE and OLE had lesser n-3 plasma polyunsaturated fatty acids and greater monounsaturated free fatty acids compared to control. The n-3-fatty acid mobilization was directly correlated with greater cystine and inversely with oxidized glutathione/reduced glutathione (GSSH/GSH) levels. This faster use of n-3 fatty acids might act as an indicator of glutathione synthesis mediated by an increase of cystine in plasma. Different correlations and linear adjustments were observed between plasma antioxidant power and free cystine, free glycine, free glutamine, monounsaturated free fatty acids, and total n-3. The best response to stress was found in VEOLE. Cortisol reached the greatest positive correlation with plasma total n-3 fatty acids, which suggests a faster uptake of n-3 for biological functions such as stress control or energy supply in the brain. From a practical point of view, an enhanced oxidative status as well as control of physiological stress prior to slaughter by the combined antioxidants supplementation might have positive effects on pork quality.