High prevalence and seasonal patterns of vitamin D deficiency in children and adolescents in Central China: a three-year single-center study.

Objective: This study aimed to determine the prevalence and associated factors of vitamin D deficiency and insufficiency in children and adolescents in Central China. Methods: In total, 8,248 children and adolescents aged 0-18 years at a children's hospital from January 2019 to February 2022, were recruited. Their serum vitamin D levels were measured, and monthly meteorological and air pollution data were collected. Results: The overall mean serum vitamin D level was 37.7 ± 17.7 ng/mL, and the prevalence of vitamin D deficiency and insufficiency was 17.7 % and 23.4 %, respectively. Children aged 13-18 years had the highest vitamin D deficiency rate (64.1 %) and the lowest sufficiency rate (4.8 %). The incidence of vitamin D deficiency in girls, especially those aged 6-13 years and 13-18 years, was higher compared to boys. The highest prevalence of vitamin D deficiency was observed in winter (23.2 %), whereas the lowest was found in autumn (12.0 %). Vitamin D insufficiency was most prevalent in summer (27.0 %), significantly higher than in other seasons. Girls were more prone than boys to vitamin D deficiency in spring and summer. Stepwise multiple linear regression analysis showed a positive correlation between vitamin D levels, nitrogen dioxide concentrations, and sunshine hours and a negative correlation with particulate matter 2.5 (PM2.5). Conclusion: Our study found high vitamin D deficiency among children in central China, especially girls aged 13-18. Strategies should include promoting sunlight, reducing air pollution, and considering supplementation, particularly in spring and summer.