The Relationship Between Serum Copper and Overweight/Obesity: a Meta-analysis

The relationship between serum copper (Cu) level and overweight/obesity remains controversial. The purpose of this meta-analysis is to evaluate the relationship. A comprehensive literature search was performed in PubMed, Web of Science, China National Knowledge Infrastructure (CNKI), and Wanfang databases for relevant articles until March 20, 2019. The random-effect model (REM) was adopted to compute the combined standardized mean difference (SMD) with 95% confidence interval (CI). Publication bias was estimated using the visualization of funnel plots and Egger's test. In the end, twenty-one articles were included in the meta-analysis. Compared with controls, serum Cu level was higher in obese children (SMD (95% CI) 0.74 (0.16, 1.32)) and in obese adults (SMD (95% CI) 0.39 (0.02, 0.76)). There was no significant difference in serum Cu between overweight and control groups in children (SMD (95% CI) 1.52 (- 0.07, 3.12)) and in adults (SMD (95% CI) 0.16 (- 0.06, 0.38)). Moreover, subgroup analysis revealed a higher serum Cu level in obese children (SMD (95% CI) 0.90 (0.36, 1.45)) and obese adults (SMD (95% CI) 0.47 (0.05, 0.88)) compared with healthy weight controls. The SMD differs significantly between obese children diagnosed by weight-for-height and controls (SMD (95% CI) 1.56 (0.57, 2.55)), and there was a significant difference of serum Cu level between obese adults diagnosed by BMI (WHO) and controls (SMD (95% CI) 0.54 (0.08, 1.01)). This meta-analysis indicates that a higher serum Cu level might be associated with the risk of obesity in children and adults, and these findings need to be further confirmed.