ObjectivesEvidence of the association between vitamin D and cardiovascular risk factors in the young is limited. We therefore assessed the relationships between circulating 25-hydroxyvitamin D₃(25(OH)D₃) and metabolic syndrome (MetS), its components, and early atherosclerotic changes in 452 (304 overweight/obese and 148 healthy, normal weight) Caucasian children.MethodsWe determined serum 25(OH)D₃concentrations in relation to MetS, its components (central obesity, hypertension, low high-density lipoprotein (HDL)-cholesterol, hypertriglyceridemia, glucose impairment, and/or insulin resistance (IR)), and impairment of flow-mediated vasodilatation (FMD) and increased carotid intima–media thickness (cIMT) – two markers of subclinical atherosclerosis.ResultsHigher 25(OH)D₃was significantly associated with a reduced presence of MetS. Obesity, central obesity, hypertension, hypertriglyceridemia, low HDL-cholesterol, IR, and MetS were all associated with increased odds of having low 25(OH)D₃levels, after adjustment for age, sex, and Tanner stage. After additional adjustment for SDS-body mass index, elevated blood pressure (BP) and MetS remained significantly associated with low vitamin D status. The adjusted odds ratio (95% confidence interval) for those in the lowest (<17 ng/ml) compared with the highest tertile (>27 ng/ml) of 25(OH)D₃for hypertension was 1.72 (1.02–2.92), and for MetS, it was 2.30 (1.20–4.40). A similar pattern of association between 25(OH)D₃, high BP, and MetS was observed when models were adjusted for waist circumference. No correlation was found between 25(OH)D₃concentrations and either FMD or cIMT.ConclusionsLow 25(OH)D₃levels in Caucasian children are inversely related to total adiposity, MetS, and hypertension.