The association between serum zinc level and overweight/obesity: a meta-analysis

PurposeThe association between serum zinc level and overweight/obesity remains controversial. Hence, we performed a meta-analysis to summarize the relationships.MethodsA systematic literature search was performed in PubMed, Web of Science and Embase for relevant English articles up to April 20, 2018. The pooled standardized mean difference (SMD) with 95% confidence interval (CI) was calculated with the random-effect model.ResultsFor children and adults, the results showed that serum zinc level was significantly lower in the cases compared to controls ([SMD (95% CI): -1.13 (-2.03, -0.23), Z=2.45, P for Z=0.014; I-2=97.1%, P for I-2<0.001] and [SMD (95% CI): -0.41 (-0.68, -0.15), Z=3.03, P for Z=0.002; I-2=62.9%, P for I-2=0.009], respectively). The difference of serum zinc level between overweight adults and controls was not statistically significant [SMD (95% CI): -0.09 (-0.27, 0.09), Z=0.97, P for Z=0.334; I-2=0.0%, P for I-2=0.411]. In subgroup analyses, a lower serum zinc level in obese children compared with non-obese controls was observed [SMD (95% CI): -2.14 (-3.20, -1.09)], and the SMD differ significantly between obese adults and controls in the case-control studies [SMD (95% CI): -0.49 (-0.90, -0.08)].ConclusionOur meta-analysis suggested that the serum zinc level was significantly lower in obese children and adults. More large observational studies are required to confirm these results in future research.