关键词: 营养状况, 维生素D, 25羟维生素D, 25（OH）D, 儿童, Meta分析, 中国

Abstract: Background　The global vitamin D nutritional status has attracted much attention recently. Vitamin D nutritional status may differ by country or region. There are few multicenter studies with a large sample size on vitamin D nutritional status in Chinese children. Objective　To analyze the vitamin D nutritional status in children in Chinese mainland. Methods　Studies regarding vitamin D nutritional status in children in Chinese mainland were collected by searching databases of PubMed，Embase，The Cochrane Library，Wanfang Data，CNKI，SinoMed and CQVIP from database inception to 2020-04-08. Two researchers separately extracted information from the eligible studies，encompassing the first author，publication time，the region（northern or southern China）where participants live，size，sex ratio，age of the sample，and outcome indicators〔serum 25（OH）D level，rate of vitamin D deficiency serum 25（OH）D level <20 μg/L〕，and assessed the publication bias. Meta-analysis was carried out using RevMan 5.2 and Stata 14.0. Results　A total of 29 studies with 133 441 healthy children and adolescents were enrolled. The average serum 25（OH）D level was （29.62±12.45）μg/L for all participants. Meta-analysis indicated that the prevalence of vitamin D deficiency in all participants，participants from southern and northern China，was 21.4%〔95%CI（17.5%，25.4%）〕，17.5%〔95%CI（13.1%，22.0%）〕，and 29.0%〔95%CI（19.4%，38.6%）〕，respectively. No significant sex-based differences were found in the prevalence of vitamin D deficiency 〔OR=0.99，95%CI（0.95，1.03），P=0.71〕，and average serum 25（OH）D level〔SMD=0.01，95%CI（-0.24，0.26），P=0.95〕. Infants had higher average serum 25（OH）D level than young children〔SMD=0.16，95%CI（0.06，0.27），P=0.002〕，preschool children〔SMD=0.77，95%CI（0.55，1.00），P<0.000 01〕，and school-age children and adolescents〔SMD=0.65，95%CI（0.27，1.04），P=0.000 1〕. In participants from southern China，infants had higher average serum 25（OH）D level than young children〔SMD=1.51，95%CI（0.31，2.72），P=0.01〕，preschool children〔SMD=6.22，95%CI（3.97，8.47），P<0.000 01〕，and school-age children and adolescents〔SMD=6.80，95%CI（2.95，10.65），P<0.000 5〕. In those from northern China，infants had higher average serum 25（OH）D level than young children〔SMD=1.23，95%CI（0.33，2.12），P=0.007〕and preschool children〔SMD=8.41，95%CI（2.04，14.79），P=0.01〕. Young children had higher average serum 25（OH）D level than preschool children〔SMD=0.61，95%CI（0.43，0.80），P<0.000 01〕，and school-age children and adolescents〔SMD=0.65，95%CI（0.27，1.04），P=0.001〕. In those from southern China，young children had higher average serum 25（OH）D level than preschool children〔SMD=5.53，95%CI（3.57，7.49），P<0.000 01〕，and school-age children and adolescents〔SMD=6.07，95%CI（3.04，9.10），P<0.000 1〕. In those from northern China，young children had higher average serum 25（OH）D level than preschool children 〔SMD=6.56，95%CI（1.19，11.92），P=0.02〕. Preschool children had higher average serum 25（OH）D level than school-age children and adolescents〔SMD=0.33，95%CI（0.15，0.51），P=0.000 4〕. In those from southern China，the average serum 25（OH）D level in preschool children was higher than that in school-age children and adolescents〔SMD=1.89，95%CI（0.58，3.21），P<0.005〕. In those from northern China，the average serum 25（OH）D level in preschool children was higher than that in school-age children and adolescents with no statistical difference〔SMD=4.94，95%CI（1.51，8.38），P=0.005〕. Conclusion　In Chinese mainland，the prevalence of vitamin D deficiency in children was relatively high. The vitamin D level was not associated with sex，but may be closely related to age. However，our conclusion still needs to be verified by further research.

Key words: Nutritional status, Vitamin D, 25 hydroxy vitamin D, 25（OH）D, Child, Meta-analysis, China