title: Relationships among diet, physical activity, and dual plane dual-energy X-ray absorptiometry bone outcomes in pre-pubertalgirls.
abstract: In pre-pubertal girls, nutrient intakes and non-aquatic organized activity were evaluated as factors in vertebral body bone mass, structure, and strength. Activity, vitamin B12, and dietary fiber predicted bone outcomes most consistently. Exercise and vitamin B12appear beneficial, whereas high fiber intake appears to be adverse for vertebral body development.
  
  
  OBJECTIVE
  Childhood development sets the baseline for adult fracture risk. Most studies evaluate development using postero-anterior (PA) dual-energy X-ray absorptiometry (DXA) areal bone mineral density, bone mineral content, and bone mineral apparent density. In a prior analysis, we demonstrated that PA DXA reflects posterior element properties, rather than vertebral body fracture sites, such that loading is associated with subtle differences in vertebral body geometry, not 3D density. The current analysis is restricted to pre-pubertal girls, for a focused exploration of key nutrient intakes and physical activity as factors in dual plane indices of vertebral body geometry, density, and strength.
  
  
  METHODS
  This cross-sectional analysis used paired PA and supine lateral (LAT) lumbar spine DXA scans to assess "3D" vertebral body bone mineral apparent density (PALATBMAD), "3D" index of structural strength in axial compression (PALATIBS), and fracture risk index (PALATFRI). Diet data were collected using the Youth/Adolescent Questionnaire (YAQ, 1995); organized physical activity was recorded via calendar-based form. Pearson correlations and backward stepwise multiple linear regression analyzed associations among key nutrients, physical activity, and bone outcomes.
  
  
  RESULTS
  After accounting for activity and key covariates, fiber, unsupplemented vitamin B12, zinc, carbohydrate, vitamin C, unsupplemented magnesium, and unsupplemented calcium intake explained significant variance for one or more bone outcomes (p < 0.05). After adjustment for influential key nutrients and covariates, activity exposure was associated with postero-anterior (PA) areal bone mineral density, PA bone mineral content, PA width, lateral (LAT) BMC, "3D" bone cross-sectional area (coronal plane), "3D" PALATIBS, and PALATFRI benefits (p < 0.05).
  
  
  CONCLUSIONS
  Physical activity, fiber intake, and unsupplemented B12intake appear to influence vertebral body bone mass, density, geometry, and strength in well-nourished pre-pubertal girls; high fiber intakes may adversely affect childhood vertebral body growth.
authors.affiliation: Nutrition Science and Dietetics Program, Syracuse University, 1645 Belleville Way #B, Sunnyvale, CA, 94087, USA.
authors.forename: Jie
authors.initials: J
authors.lastname: Ren
authors.affiliation: Nutrition Science and Dietetics Program, Syracuse University, 550L White Hall, Syracuse, NY, 13244, USA.
authors.forename: Lynn S
authors.initials: LS
authors.lastname: Brann
authors.affiliation: Nutrition Science and Dietetics Program, Syracuse University, 550L White Hall, Syracuse, NY, 13244, USA.
authors.forename: Kay S
authors.initials: KS
authors.lastname: Bruening
authors.affiliation: Department of Orthopedics and Rehabilitation, University of Wisconsin-Madison, 1685 Highland Ave., 6th floor, Madison, WI, 53705, USA.
authors.forename: Tamara A
authors.initials: TA
authors.lastname: Scerpella
authors.affiliation: Department of Orthopedic Surgery, Upstate Medical University, 750 East Adams Street, Syracuse, NY, 13210, USA. dowthwaj@upstate.edu.
authors.forename: Jodi N
authors.initials: JN
authors.lastname: Dowthwaite
mesh_terms: D015502:Absorptiometry, Photon / Q000379:methods; D000293:Adolescent; D050499:Adrenarche / Q000502:physiology; D015519:Bone Density / Q000502:physiology*; D002648:Child; D002657:Child Development / Q000502:physiology*; D003430:Cross-Sectional Studies; D004032:Diet; D004043:Dietary Fiber / Q000009:adverse effects / Q000378:metabolism*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D016014:Linear Models; D015596:Nutrition Assessment; D013131:Spine / Q000000981:diagnostic imaging / Q000254:growth & development; D014805:Vitamin B 12 / Q000378:metabolism*
chemical_list: D004043:Dietary Fiber; D014805:Vitamin B 12
keywords: Bone density; Bone geometry; Children; Exercise; Female; Nutrition