Longitudinal associations between vitamin D status and biomarkers of inflammation in a pan-European cohort of children and adolescents

PurposeTo investigate longitudinal associations between the vitamin D status and inflammatory markers in children and adolescents.MethodsChildren from eight European countries from the IDEFICS/I.Family cohort with repeated measurements were included in this study. A linear mixed-effect model was used to model the association of serum 25(OH)D as independent variable and z-scores of inflammatory markers [CRP, cytokines, adipokines, combined inflammation score] as dependent variables, where one level accounts for differences between individuals and the other for changes over age within individuals.ResultsA total of 1,582 children were included in the study. In the adjusted model, 25(OH)D levels were positively associated with adiponectin (beta = 0.11 [95% CI 0.07; 0.16]) and negatively with the inflammation score (beta = - 0.24 [95% CI - 0.40; - 0.08]) indicating that the adiponectin z-score increased by 0.11 units and the inflammation score decreased by 0.24 units per 12.5 nmol/l increase in 25(OH)D. In children with overweight or obesity, only a positive association between 25(OH)D and IP-10 was observed while in children with normal weight adiponectin was positively and the inflammation score was negatively associated. Associations of vitamin D with adiponectin and the inflammation score were stronger in girls than in boys and a positive association with TNF-alpha was observed only in girls.ConclusionOur results suggest that an increase in vitamin D concentrations may help to regulate inflammatory biomarkers. However, it seems to be no benefit of a better vitamin D status in children with overweight/obesity unless their weight is managed to achieve an improved inflammatory marker status.