Association of vitamin D insufficiency with adiposity and metabolic disorders in Brazilian adolescents

Objective: The present study aimed to evaluate the frequency of deficiency/ insufficiency of vitamin D in adolescents and its relationship to overweight and metabolic disorders. Design: Cross-sectional study. Nutritional status was assessed by BMI according to WHO recommendations. Dietary intake was evaluated using a 3 d dietary record. The biochemical evaluation comprised measurements of serum lipids, lipoproteins, glucose, insulin, calcidiol (25(OH) D) and parathyroid hormone. Insulin resistance was calculated using the homeostasis model assessment. Body composition and blood pressure were assessed. Setting: Fifteen schools (eight public and seven private) in the central city of Juiz de Fora, Brazil. Subjects: The analysis included a study population of 160 adolescents (seventyseven eutrophic and eighty-three overweight) aged 15 to 17 years. Results: Vitamin D deficiency and insufficiency was observed in 1.25 and 70.6% of adolescents, respectively. Serum 25(OH) D levels were statistically lower in adolescents with weight excess, abdominal obesity, hypercholesterolaemia, higher levels of parathyroid hormone, insulin resistance, hyperinsulinaemia and hypertension (P< 0.05). Lower BMI and waist circumference were observed in the third (highest) tertile of vitamin D intake for all adolescents. The high prevalence of vitamin D insufficiency is primarily nutritional and reflects a low vitamin D intake. Conclusions: Our results support the negative association among serum 25(OH) D levels and vitamin D intake with non-skeletal outcomes in Brazilian adolescents. Vitamin D fortification of foods and/or the use of vitamin D supplements need to be considered to raise vitamin D intake in the adolescent population, even in a sunny country like Brazil.