Date of Award

6-2014

Embargo Date

1-31-2015

Degree Name

Master of Science (MS)

Department

Nutrition Science and Dietetics

Advisor(s)

Lynn S. Brann

Keywords

Macronutrient, Micronutrient, Physical Activity, Pre-pubertal Girls, Vertebra

Abstract

Osteoporotic fractures are a leading cause of morbidity in the U.S. Bone mass levels during childhood play a key role in determining peak bone mass and hence the risk of osteoporosis in later life. The aim of the study was to evaluate how key bone nutrients and organized physical activity affect bone outcomes in pre-pubertal girls using Dual Plane Dual X-Ray Absorptiometry (DXA). This cross-sectional analysis used a subset of participants (n=50) from a longitudinal study of bone growth in relation to physical activity. Dietary data were collected using the Youth/Adolescent Questionnaire (YAQ, 1995) and organized activity was recorded semi-annually to yield annual means (hours per week). Paired postero-anterior (PA) and supine lateral lumbar spine (LAT) Dual X-Ray Absorptiometry (DXA) scans provided L3 PA bone mineral density (PABMD), PA vertebrae width (PAWIDTH), bone mineral content (PABMC, LATBMC), LAT vertebral height (LATHEIGHT), LAT vertebral depth (LATDEPTH), paired vertebral volume (PALATV) and bone mineral apparent density (PALATBMAD). Bone strength in axial compression (PALATIBS) and fracture risk index (FRI) were calculated. Multiple linear regressions were used to analyze the association between key bone nutrients, level of physical activity, and bone outcomes. Carbohydrate, fiber, and zinc intake significantly correlated with bone outcomes. After accounting for age, height, and activity, focal nutrients were not significant factors for prediction bone outcomes. Physical activity was positively associated with PABMD, PABMC, PAWIDTH, LATBMC, PALATIBS after adjusting for age, height, and all the key nutrients. We found physical activity has greater explanatory value than nutrient intakes for bone content, density, geometry and strength in well-nourished pre-pubertal girls.

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Open Access

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