Effects of zinc on plasma lipoprotein cholesterol concentrations in humans: A meta-analysis of randomised controlled trials

Background: Studies in humans and animals suggest that zinc has the potential to affect lipoprotein metabolism and hence impact cardiovascular disease risk. Methods: A meta-analysis of controlled clinical trials was conducted to determine the effect of zinc supplementation on plasma cholesterol and triglyceride concentrations in humans. Potentially relevant studies were identified from a literature search covering the period 1980-2008 (inclusive), and additional citation searches. Results: Thirty three interventions (n= 14,238 subjects) were included in the random effects meta-analysis. No overall significant effects of zinc supplementation were observed for plasma cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol or plasma triglyceride concentrations. Plasma zinc concentrations increased significantly (+2.42 ± 0.25 μmol/L, P<. 0.001; n= 14,047). Secondary analyses in individuals classified as healthy revealed that zinc supplementation is associated with a significant decrease in plasma HDL cholesterol concentrations (-0.10 ± 0.02. mmol/L, P<. 0.001; n= 13,215), equivalent to a 7% decrease from baseline. Conclusion: No effect of zinc supplementation on plasma lipoproteins was detected in the overall analysis. In individuals classified as healthy, zinc supplementation is associated with a decrease in HDL cholesterol concentrations and thus contributes to an increased risk of coronary heart disease.