Association Between Vitamin D Intake and Obesity During Pre- and Early Adolescence

Background: Prevalence of obesity in US children has increased substantially. The influence of vitamin D intake on body mass index (BMI) is yet to be clearly defined. Results are mixed regarding the relationship of vitamin D deficiency with obesity in children. The objective of this study was to examine the association between vitamin D intake and BMI over a 6 month period in pre-to early adolescent children in Pittsburgh, PA. Methods: Secondary analysis was done on 256 healthy 6-14 year old (54% male) Caucasian and African American (70%) children from Pittsburgh, PA. Participants completed a food frequency questionnaire (FFQ) and a Sun Exposure Questionnaire (SEQ) and provided anthropometric measures at 2 time points 6 months apart. Vitamin D intake was compared by BMI status (normal = \u3c85th percentile, overweight = 85th to 95th percentile, obese = \u3e95th percentile) as well as by change in BMI over 6 months. Statistical analysis included descriptive statistics, Kruskal-Wallis analysis of variance, Spearman’s correlation, Chi Square test, and regression analysis (vitamin D intake, gender, race, baseline BMI, total energy intake, sun exposure and sunscreen use). Results: Median reported vitamin D intake was 245.85 IU at baseline and 382.51 IU at 6 month follow up. After subdividing children by BMI, at baseline the obese group reported lowest median intake (188 IU) and at 6 month follow up the normal group reported lowest median intake (374 IU) (P=0.03). Overall relation between vitamin D intake and BMI was significant (P=0.033) but weak (r=-0.015). Regression analysis revealed only baseline BMI status (P=\u3c0.001) as a predictor of 6 month follow up BMI. No relation was observed between change in BMI and vitamin D intake. Conclusion: The results of this study do not support a strong relationship between vitamin D intake and change in BMI status over a 6 month time period