48 VITAMIN D AND CARDIOMETABOLIC RISK FACTORS IN FOURTEEN YEAR OLD ADOLESCENTS

Background and Objective: Low blood vitamin D levels may contribute to the high and increasing prevalence of cardiovascular disease in adults. However, the association between cardiovascular risk factors and vitamin D levels has not been well studied in children. Design and Methods: Serum vitamin D was assayed using 25-dihydroxyvitamin D in 1380 adolescents aged 14-years from an unselected community birth cohort, the Western Australian Pregnancy Cohort (Raine) Study. Using cluster analysis we previously identified 29% of the adolescents in a high-risk metabolic cluster group (based on levels of triglycerides, BMI, HOMA, and systolic blood pressure) similar to adults with the metabolic syndrome (1). Logistic regression was used to investigate the influence of seasonally adjusted vitamin D levels on the metabolic risk outcome. Results: The mean vitamin D was 88.3 nmol/L, with a range between 29.5 and 257.5 nmol/L. Increasing vitamin D was associated with higher odds of low-risk metabolic cluster group membership (P<0.001, OR = 1.02, 95% CI 1.01-1.03, low risk group mean vitamin D 91.0 nmol/L, high risk cluster mean vitamin D 79.3 nmol/L). Conclusions: This is the first study to show increased serum vitamin D associates with reduced cardiovascular risk factors in adolescents. Cardiovascular benefits of increased vitamin D may relate to inhibition of vascular smooth muscle proliferation, suppression of vascular calcification, down regulation of pro-inflammatory cytokines and the action of vitamin D as a negative endocrine regulator of the renin-angiotensin system. Controlled clinical trials are needed to investigate whether oral vitamin D supplementation reduces cardiovascular disease morbidity and mortality. Reference 1. Huang R-C, Mori TA, Burke V, Newnham J, Stanley FJ, Landau LI, et al. Synergy Between Adiposity, Insulin Resistance, Metabolic Risk Factors, and Inflammation in Adolescents. Diabetes Care. 2009 April 1, 2009;32(4):695-701.