Vitamin DVitamin D DeficiencyCalcifediol25-Hydroxyvitamin D3 1-alpha-Hydroxylase25-Hydroxyvitamin D 2CholecalciferolHydroxycholecalciferolsErgocalciferolsParathyroid HormoneSeasonsDihydroxycholecalciferolsVitaminsDietary Supplements24,25-Dihydroxyvitamin D 3Steroid HydroxylasesReceptors, CalcitriolSunlightVitamin D-Binding ProteinCalcitriolRicketsCholestanetriol 26-MonooxygenaseCross-Sectional StudiesCalcium, DietaryRisk FactorsBiological MarkersProspective StudiesCase-Control StudiesBone DensityCalciumLinear ModelsEuropean Continental Ancestry GroupAfrican AmericansMultivariate AnalysisPrevalenceCohort StudiesNorwayUnited StatesOdds RatioBody Mass IndexPhosphorusOsteomalaciaDouble-Blind MethodSkin PigmentationNutritional StatusHydroxylationBone and BonesBone Density Conservation AgentsCytochrome P-450 Enzyme SystemKidneyDietNutrition SurveysPhosphatesChromatography, High Pressure LiquidHypoparathyroidismBostonFood, FortifiedFractures, BoneHypercalcemiaTandem Mass SpectrometryAbsorptiometry, PhotonCholestenesOsteoporosisDehydrocholesterolsRadioimmunoassayAlkaline PhosphataseNutritional RequirementsChromatography, LiquidPostmenopauseHyperparathyroidism, SecondaryLogistic ModelsHypocalcemiaHyperparathyroidismSunscreening AgentsNutrition PolicyMass SpectrometryHyperparathyroidism, PrimaryAdrenodoxinBone Diseases, MetabolicIntestinal AbsorptionNebraskaRenal Insufficiency, ChronicAfrican Continental Ancestry GroupHip FracturesFollow-Up StudiesSpectrophotometry, UltravioletPregnancyReference ValuesTime FactorsMilkOsteocalcinMongoliaBone ResorptionLongitudinal StudiesRegression AnalysisAge FactorsUltraviolet RaysChickensRiskQuestionnairesCardiovascular Diseases