Serum 25-hydroxyvitamin D levels, obesity and the metabolic syndrome among Korean children

Background and Aim: Evidence of the relationship between serum vitamin D levels and cardiovascular risk factors in children is limited. We investigated the associations between serum vitamin D levels (25-hydroxyvitamin D [25(OH)D]) and obesity and metabolic syndrome and its components in Korean children. Methods and Results: We recruited 1660, nine-year-old, Korean children (904 boys and 756 girls) who voluntarily participated in this study while being examined during school-based health examinations. We measured anthropometric variables (height and weight), metabolic parameters (blood pressure, fasting plasma glucose, triglyceride, and HDL cholesterol levels) and serum vitamin D levels. We analyzed the data using multivariate logistic regression models. Mean 25(OH)D levels were lower in children defined as obese or abdominally obese (P < 0.001). When serum levels of 25(OH)D were divided into quartiles, BMI, waist circumference, and triglyceride levels were lower, and HDL cholesterol levels were higher, as vitamin D levels increased. Using children from the highest quartile of 25(OH)D levels as a referent, the adjusted ORs (95% CI) for obesity in those in the third, second, and lowest quartiles of 25(OH)D levels were 1.55 (1.01-2.40), 1.87 (1.22-2.85), and 2.59 (1.71-3.90), respectively (P for trend <0.001). For abdominal obesity the ORs (CI) were 2.08 (1.20-3.60), 2.32 (1.36-3.95), and 2.96 (1.75-5.00) (P for trend<0.001), and for metabolic syndrome they were 2.60 (1.08-6.30), 4.00 (1.73-9.26), and 4.25 (1.84-9.85), respectively (P for trend <0.05). Conclusions: We found low vitamin D levels in Korean children to be associated with obesity and metabolic syndrome. Insufficient serum vitamin D levels in children may be a risk factor of obesity and metabolic syndrome.