Serum/Plasma Zinc Is Apparently Increased in Ischemic Stroke: a Meta-analysis

Zinc (Zn) is found in many neuronal pathways in the brain and has implications for neuromodulation and cerebrovascular disease. However, the association between Zn levels and stroke risk remains controversial. Therefore, we conducted a meta-analysis to explore these relationships. A systematic literature search using PubMed, EMBASE database, and Google Scholar was performed for relevant articles from inception to August 2020. Standardized mean differences (SMDs) and 95% confidence intervals (CIs) were considered the effect sizes and statistical analyses were performed using Stata 12.0. A total of 12 studies involving 1878 cases of stroke and 1754 controls were enrolled. Overall, the meta-analysis demonstrated no significant difference in Zn levels between the stroke group and control group (SMD =-0.18, 95% CI =-0.69 to 0.32, P = 0.480). Subgroup analysis showed that type of stroke had an influence on the Zn levels. A meta-analysis of nine ischemic stroke (IS) studies, which included 1645 cases and 1585 controls, revealed that the Zn levels were significantly higher in IS patients than in controls (SMD (95% CI): 0.61(0.04, 1.19), P = 0.036), but no significant association was found between Zn levels and risk of hemorrhagic stroke (P = 0.113). Egger's test indicated no significant publication bias. This meta-analysis indicates that higher Zn levels may be associated with increased risk of IS; however, these findings should be further confirmed.