Ju SY, et al. - This systematic review and dose-response meta-analysis evaluated the link between 25-hydroxyvitamin D (25OHD) serum levels and frailty. Data from cross-sectional and cohort studies were collected from the PubMed, EMBASE, and Cochrane Library databases of Elsevier through February 2017, and reported adjusted risk ratios with 95% confidence intervals for frailty with ≥3 categories of 25OHD serum levels. In the six cross-sectional and four prospective cohort studies, the respective pooled risk estimates of frailty syndrome per 25-nmol/L increment in serum 25OHD concentration were 0.88 and 0.89. Findings showed a significant and direct association of serum 25OHD levels with the risk of frailty.