Assessment of the association between serum 25-hydroxyvitamin D and excess weight in schoolchildren from urban and rural areas

Abstract

Introduction and Objective: It remains controversial whether vitamin D insufficiency is inversely proportional to body mass index, and there is still little information about vitamin D and its relationship with obesity in Brazilian schoolchildren. The objective was to evaluate the serum concentrations of 25-hydroxyvitamin D in schoolchildren and identify its association with nutritional status. Materials and Methods: Cross-sectional study with 262 students (aged 6-10 years), regularly enrolled in public schools, with the primary outcome being serum vitamin D concentration, with data collection in the spring. A standardized questionnaire was applied to legal guardians and anthropometric and pubertal staging assessments were carried out, blood collection and 25-hydroxyvitamin D dosage (electrochemiluminescence; deficiency <20 ng/mL, insufficiency 20-30 ng/mL and normality >30 ng/mL). Results: The mean age was 8.7 ±1.3 years; 53% male; prepubertal majority (>80%). The average of 25-hydroxyvitamin D was 40.4 ±10.2 ng/mL, with a prevalence of normality of 85.1%; 29.4% were overweight, with no association with serum vitamin D. There was an association of 25-hydroxyvitamin D with the rural location of residence (p<0.01) and school (p<0.05), as well as with the habit of sun exposure (p<0.05). Conclusion: Prevalence of 25-hydroxyvitamin D deficiency/insufficiency was lower than in national and international studies; excess weight was similar to that found in a previous national study, without association with serum vitamin D. Children from the rural area had higher serum concentrations of 25-hydroxyvitamin D when compared to those from the urban area, as well as those who were exposed to the sun.