Associations between fat-soluble vitamin status, growth, and development in Chinese children aged 3-14 years: a cross-sectional study.

BACKGROUND: The status of fat-soluble vitamins (A, D, E, K1, and K2) is crucial for childhood growth and development. However, comprehensive data on their levels-particularly vitamin K2-and their association with growth phenotypes in Chinese children remain limited. This study aimed to establish reference data and investigate these relationships. METHODS: A cross-sectional study was conducted involving 1,802 children (892 boys, 910 girls) aged 3-14 years undergoing health check-ups in Ruian City, located in a subtropical monsoon climate zone in Eastern China. Serum levels of vitamins A, D, E, K1, and K2 were measured using liquid chromatography-tandem mass spectrometry. Participants were classified into healthy, short stature, obesity, or precocious puberty groups based on standardized diagnostic criteria (detailed in Methods). Differences in vitamin levels were analyzed across sex, age, season, and growth groups, and multivariate regression models were used to adjust for potential confounders. RESULTS: Vitamin D (VD) and vitamin K2 (VK2) deficiencies were common. The overall insufficiency rates were: for VD, 13.6% in boys and 22.4% in girls; for VK2, 36.0% in boys and 39.7% in girls. Marked seasonal variations were observed: VD deficiency peaked in winter and spring, especially among girls aged 9-12 years, while VK2 deficiency was prominent in boys aged 8-9 years during spring. After adjusting for age, sex, and BMI, a significant inverse association was observed between VK status and precocious puberty in girls (P < 0.001). Compared with the healthy group, boys with obesity had higher vitamin A (VA) levels (potentially related to adipose tissue distribution volume), whereas girls with precocious puberty showed significantly lower levels of both VK1 and VK2 (P < 0.0001), leading to the hypothesis that this may be linked to accelerated bone metabolism. CONCLUSION: This study reveals a high prevalence of VD and VK2 deficiency among children in Eastern China, with distinct seasonal and gender patterns. In multivariate analysis, an independent inverse association was observed between VK status and precocious puberty in girls, suggesting a possible metabolic link that warrants further investigation. However, given the cross-sectional design, no causal inference can be drawn, and this finding should be regarded as hypothesis-generating. These results underscore the need for seasonally tailored, vitamin-specific nutritional attention in pediatric populations, while highlighting the importance of prospective studies to clarify the clinical significance of these associations.