The association between blood concentration of 25- hydroxyvitamin D and sarcopenia: a meta-analysis.

Associations between blood 25-hydroxyvitamin D (25(OH)D) concentration and sarcopenia remain controversial; thus, this meta-analysis was conducted to explore the relationship between blood 25(OH)D concentration and sarcopenia.We searched the PubMed and EMBASE databases for relevant published observational studies that investigated blood 25(OH)D concentration and sarcopenia up to June 2017.We then investigated data from these studies that compared blood 25(OH)D concentrations between the sarcopenia and healthy control groups. A random-effect model was used to calculate the pooled weighted mean difference (WMD) of blood 25(OH)D concentration with a 95% confidence interval (95% CI).Twelve studies (eight cross-sectional, two matched case-control, and two prospective cohort studies) with a total of 22,590 individuals were included. Sarcopenic individuals had lower blood 25(OH)D concentrations than healthy controls (WMD=-2.14, 95% CI: -2.81--1.48; I2=74.6%). Subgroup analysis showed that the methods of assessing both blood 25(OH)D concentrations and sarcopenia might be sources of heterogeneity, and further showed that studies excluding obese individuals and different sarcopenia assessment criteria enhanced the relationship. Sensitivity analysis by one-study-removed confirmed the robustness of these results.Our study shows that sarcopenic adults have lower blood 25(OH)D concentrations. Further high-quality large-scale prospective cohort studies are needed to confirm these findings.