[Association of vitamin D nutritional status with body muscle mass in school-age children adolescents].

To investigate the association between vitamin D nutritional status and the body muscle mass in children. Data were obtained from School-based Cardiovascular and Bone Health Promotion Program. In 2017, a total of 15 391 children aged 6-16 years in Beijing were selected through stratified cluster sampling in baseline survey. A follow-up investigation was conducted in 2019. The questionnaire survey and the detection of serum 25-hydroxyvitamin D [25(OH)D] level were conducted. The bioelectrical impedance analysis (BIA) apparatus was used to measure body muscle mass, and muscle mass index (MMI) was calculated. Multivariable linear models were used to analyze the association of vitamin D nutritional status with the baseline and follow-up MMI measures. A total of 10 890 children aged (11.5±3.3) years(boys accounting for 49.6%) were included in the analysis. The average 25(OH)D level was (35.4±12.0) nmol/L, with an adequacy ratio of 11.1%. After multivariate linear regression adjustment for age, sex, body fat mass, smoking status, alcohol use status, dairy supplement, calcium supplement, physical activity, and pubertal development, no statistically significant association between vitamin D nutritional status and baseline MMI level was observed (>0.05). For the follow-up MMI, the -score increased by 0.008 (=0.058) for per 10 nmol/L increase in 25(OH)D, which were 0.002 (=0.815) and 0.037 (=0.031) higher in children with insufficient and adequate vitamin D than those with vitamin D deficiency, respectively ( for trend =0.089). Subgroup analysis showed that in the normal BMI group, for per 10 nmol/L increase in 25 (OH) D, the MMI at baseline survey and MMI -score at follow-up of children with adequate vitamin D and increased by 0.019 and 0.014, respectively (both <0.05). Vitamin D nutritional status was related to muscle mass in children, and children with adequate vitamin D tended to obtain higher MMI. Children and adolescents are encouraged to maintain sufficient vitamin D levels, strengthen nutrition and exercise to promote body health.