Date of Award

Winter 11-14-2012

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Nutrition

First Advisor

Anita M. Nucci, PhD, MPH, RD, LD

Second Advisor

Vijay Ganji, PhD, RD

Third Advisor

Catherine McCarroll, MPH, RD, LD

Abstract

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 = <85th percentile, overweight = 85th to 95th percentile, obese = >95th 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=<0.001) 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.

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