Association of body mass index and serum vitamin D level in healthy Iranian adolescents

Abstract

Introduction: In studies of obese adolescents in various countries, vitamin D deficiency has been correlated with greater weight and elevated BMI. However, there is insufficient data on the relation between vitamin D status and body fat indexes in adolescence. The aim of this study was to investigate the association of serum (25[OH]D) concentrations with body mass index of healthy Iranian subjects to understand whether specific data on the relation between vitamin D status and body mass index is common in all populations.
Material and methods: Data was collected from 259 ambulant medical staff adults, students and other subjects who met the inclusion criteria of the study. Body mass index and fasting 25-Hydroxy vitamin D level were measured. Vitamin D deficiency was defined as having a 25(OH)D concentration < 25 nmol/L.
Results: Participants were aged 20–64 years, mean age 34 ± 9 years, and about 57.5% of the participants were women. The mean (± SD) body mass index (kg/m2) was 24.2 ± 3.8 kg/m2 (median = 23.7 kg/m2), the mean (± SD) vitamin D level of the participants was 29 ± 16 nmol/L (median = 26 nmol/L), and 48% of the participants had vitamin D deficiency. In this study, there was no significant association between vitamin D level and BMI (r = 0.064; p = 0.307) (age adjusted). Moreover, there was no association between vitamin D level and sex of the participants. In addition, no association between BMI and sex of the adolescents was seen (p; NS), but a significant association between age and vitamin D level was found (r = 0.002).
Conclusion: Our data suggests that various mechanisms could potentially contribute to the robust association of vitamin D with adiposity; in normal or near normal BMI, vitamin D status may not be correlated with age.