25-Hydroxyvitamin D3 1-alpha-Hydroxylase25-Hydroxyvitamin D 2CalcifediolVitamin DVitamin D DeficiencyCholecalciferolHydroxycholecalciferolsErgocalciferolsDihydroxycholecalciferols24,25-Dihydroxyvitamin D 3Steroid HydroxylasesParathyroid HormoneCalcitriolVitamin D-Binding ProteinRicketsSunlightCholestanetriol 26-MonooxygenaseReceptors, CalcitriolSeasonsDietary SupplementsVitaminsCalcium, DietaryPhosphorusOsteomalaciaBone DensityCalciumHydroxylationCross-Sectional StudiesNutritional StatusSkin PigmentationBone and BonesCytochrome P-450 Enzyme SystemRisk FactorsLinear ModelsProspective StudiesBone Density Conservation AgentsKidneyBiological MarkersChromatography, High Pressure LiquidCase-Control StudiesFood, FortifiedEuropean Continental Ancestry GroupDietCholestenesHypoparathyroidismPrevalenceCohort StudiesDehydrocholesterolsPhosphatesNutritional RequirementsNutrition SurveysAfrican AmericansRadioimmunoassayTandem Mass SpectrometryAbsorptiometry, PhotonBostonBody Mass IndexHypercalcemiaNutrition PolicyAlkaline PhosphataseMass SpectrometryOsteoporosisFractures, BoneAdrenodoxinPostmenopauseChromatography, LiquidIntestinal AbsorptionNebraskaUnited StatesDouble-Blind MethodHyperparathyroidism, SecondarySpectrophotometry, UltravioletHyperparathyroidismLogistic ModelsHypocalcemiaMultivariate AnalysisMilkOsteocalcinMongoliaOdds RatioHyperparathyroidism, PrimaryHip FracturesChickensBone Diseases, MetabolicParathyroid GlandsFerredoxin-NADP ReductaseAfrican Continental Ancestry GroupFat SubstitutesLow Density Lipoprotein Receptor-Related Protein-2Bone RemodelingReference ValuesRenal Insufficiency, ChronicCholesterol Side-Chain Cleavage EnzymeFollow-Up StudiesBreadBone ResorptionPregnancyFinlandTime FactorsMinerals