Lower circulating zinc and selenium levels are associated with an increased risk of asthma: evidence from a meta-analysis

Abstract

AbstractObjective:Previous studies evaluating the associations of circulating Zn and Se levels with asthma have produced inconsistent results. Therefore, we conducted a meta-analysis to summarize and quantitatively synthesize the evidence from observational research.Design:Meta-analysis.Setting:We searched PubMed, Web of Science and Scopus databases up to May 2019 for relevant available articles. Random-effects model was adopted to estimate the pooled standardized mean difference (SMD) with 95 % CI. Meta-regression analysis and ‘leave-one-out’ sensitivity analysis were used to assess heterogeneity.Participants:The meta-analysis focused on general populations.Results:A total of twenty-six studies for Zn and forty studies for Se were included in the meta-analysis. The overall analyses identified that asthma patients had lower Zn (SMD = −0·40; 95 % CI −0·77, −0·03; I2 = 94·1 %) and Se (SMD = −0·32; 95 % CI −0·48, −0·17; I2 = 90·9 %) levels in serum or plasma compared with healthy controls. After removing the studies that contributed to the heterogeneity, the pooled SMD were −0·26 (95 % CI −0·40, −0·13; I2 = 37·42 %) for Zn and −0·06 (95 % CI −0·13, 0·02; I2 = 43·54 %) for Se.Conclusions:Lower circulating Zn and Se levels might be associated with an increased risk of asthma.