International journal of clinical practice | 2021
Investigation of the clinical efficacy of Zn supplementation in improvement of oxidative stress parameters: A systematic review and dose-response meta-analysis of controlled clinical trials.
Abstract
BACKGROUND/OBJECTIVES\nClinical efficacy of Zn supplementation in improvement of oxidative stress biomarkers has been investigated in some clinical trial studies. The purpose of current dose-response meta-analysis is to systematically aggregate and evaluate all related studies to highlight the possible effect of Zn supplementation on oxidative stress.\n\n\nMETHODS\nSystematic search was performed on Scopus, PubMed/Medline, Web of Science and Embase up to December 31, 2020. Random effect method was used to perform pooled-analysis. Possible sources of heterogeneity were found using subgroup analysis and meta-regression. In the presence of publication bias, trim and fill analysis was performed to adjust the results. Non-linear relationship between effect size and variables was investigated performing dose-response analysis. Quality of included studies was assessed using Cochrane Collaboration s tool.\n\n\nRESULTS\nPooled-analysis of 18 studies showed that Zn supplementation improved MDA and Hcys levels (SMD= -1.53 μmol/L; 95% CI: -2.22, -0.85; P< 0.001 and SMD= -0.62 μmol/L; 95% CI: -1.08, -0.15; P< 0.001, respectively). There was no significant effect of Zn supplementation on TBARS (SMD= -0.59 μmol/l; 95% CI: -1.31, 0.13; P=0.108). Zn had maximum reducing effect on MDA in <40 mg/day dosage.\n\n\nCONCLUSION\nZn supplementation reduces MDA and Hcys levels, but not TBARS level. Supplementation with Zn <40 mg/day has optimum effect on MDA level. Zn supplementation could be considered clinically as a beneficial approach in amending oxidative stress.