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

Background/Objectives Clinical efficacy of zinc (Zn) supplementation in the improvement of oxidative stress biomarkers has been investigated in some clinical trial studies. The purpose of the 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. Methods Systematic search was performed on Scopus, PubMed/Medline, Web of Science and Embase up to 31 December 2020. The 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 by performing dose‐response analysis. The quality of included studies was assessed using Cochrane Collaboration's tool. Results Pooled‐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