Plasma zinc in institutionalized elderly individuals: Relation with immune and cardiometabolic biomarkers

Changes in zinc metabolism caused by aging and the institutionalization process may contribute to zinc deficiency in elderly individuals. Hypozincemia results in changes in glycemic, lipid, and inflammatory profiles. The aim of this study was to evaluate plasma zinc concentrations and their relationships with sociodemographic, dietary, inflammatory, and cardiometabolic biomarkers in institutionalized elderly individuals. A cross-sectional study was carried out including 255 elderly adults living in nursing homes. The associations between plasma zinc and dietary zinc intake, sociodemographic indicators, and glycemic, lipid, and inflammatory biomarkers were evaluated. Independent variables were analyzed according to quartiles of plasma zinc concentrations (Q1: <71.1 μg/dL; Q2: 71.1-83.3 μg/dL; Q3: <83.3-93.7 μg/dL; Q4: >93.7 μg/dL). The relationship between plasma zinc concentrations and predictor variables was also tested. In Q1, higher concentrations of the following variables were observed, compared with those in other quartiles: total cholesterol and low-density lipoprotein cholesterol (LDL-c; Q1 > Q2, Q3, Q4; all p <0.001); triglycerides (Q1 > Q3, Q4; all p < 0.001); interleukin (IL)-6 (Q1 > Q3, Q4; p = 0.024 and p = 0.010, respectively); tumor necrosis factor (TNF)-α (Q1 > Q3, p = 0.003). A significant reduction in plasma zinc concentrations was observed with increasing age-adjusted institutionalization time (Δ = − 0.10; 95% confidence interval [CI]: −0.18 to −0.01). The concentrations of total cholesterol (Δ = − 0.19; 95% CI: −0.23 to −0.15), LDL-c (Δ = − 0.19; 95% CI: −0.23 to −0.15), triglycerides (Δ = − 0.11; 95% CI: −0.16 to −0.06), IL-6 (Δ = − 1.41; 95% CI: −2.64 to −0.18), and TNF-α (Δ = − 1.04; 95% CI: −1.71 to −0.36) were also significantly increased. In conclusion, decreased plasma zinc concentrations were associated with longer institutionalization time and worse lipid and inflammatory profiles in elderly institutionalized individuals.