Vitamin D25-Hydroxyvitamin D 2Vitamin D DeficiencyCalcifediolCholecalciferol25-Hydroxyvitamin D3 1-alpha-HydroxylaseSunlightErgocalciferolsParathyroid HormoneSeasonsDietary SupplementsHydroxycholecalciferolsOsteomalaciaDihydroxycholecalciferolsVitaminsFood, Fortified24,25-Dihydroxyvitamin D 3Steroid HydroxylasesVitamin D-Binding ProteinRicketsBone DensityNutritional StatusCalcitriolCross-Sectional StudiesCholestanetriol 26-MonooxygenaseCalciumLinear ModelsEuropean Continental Ancestry GroupAbsorptiometry, PhotonMilkPostmenopauseRisk FactorsReceptors, CalcitriolAfrican AmericansCalcium, DietarySkin PigmentationPhosphorusPlasmaBone Density Conservation AgentsBone and BonesNutritional RequirementsProspective StudiesBiological MarkersDietCase-Control StudiesHydroxylationPrevalenceRadioimmunoassayMongoliaKidneyCohort StudiesChromatography, High Pressure LiquidPhosphatesAlkaline PhosphataseBreadNutrition SurveysHypercalcemiaCytochrome P-450 Enzyme SystemNutrition PolicyBody Mass IndexDouble-Blind MethodTandem Mass SpectrometryHyperparathyroidism, SecondaryChromatography, LiquidReference ValuesIntestinal AbsorptionMaternal Nutritional Physiological PhenomenaUnited StatesHyperparathyroidismPregnancyTime FactorsLogistic ModelsMultivariate AnalysisDose-Response Relationship, DrugHip FracturesOdds RatioCholestenesFinlandDehydrocholesterolsHypoparathyroidism2,4-Dichlorophenoxyacetic AcidPlasma CellsAfrican Continental Ancestry GroupFollow-Up StudiesMass SpectrometryRenal Insufficiency, ChronicRegression AnalysisOsteoporosis, PostmenopausalPremenopauseBone ResorptionAge FactorsMaineObesityUltraviolet RaysBostonImmunoassayAgingFrail ElderlyInsulin ResistanceOsteoporosis