Vitamin D25-Hydroxyvitamin D3 1-alpha-Hydroxylase25-Hydroxyvitamin D 2CalcifediolVitamin D DeficiencyCholecalciferolHydroxycholecalciferolsVitaminsErgocalciferolsVitamin ADihydroxycholecalciferols24,25-Dihydroxyvitamin D 3Steroid HydroxylasesParathyroid HormoneVitamin D-Binding ProteinCalcitriolVitamin ERicketsSunlightReceptors, CalcitriolCholestanetriol 26-MonooxygenaseVitamin B 12Dietary SupplementsVitamin A DeficiencySeasonsCalcium, DietaryVitamin K 1OsteomalaciaPhosphorusNutritional StatusBone DensityCalciumVitamin B 6Cross-Sectional StudiesVitamin E DeficiencyVitamin B 12 DeficiencyHydroxylationBone and BonesSkin PigmentationDietRisk FactorsBone Density Conservation AgentsCytochrome P-450 Enzyme SystemFood, FortifiedProspective StudiesLinear ModelsVitamin K DeficiencyBiological MarkersKidneyChromatography, High Pressure LiquidVitamin B 6 DeficiencyNutritional RequirementsCase-Control StudiesAscorbic AcidEuropean Continental Ancestry GroupPrevalenceCohort StudiesNutrition SurveysHypoparathyroidismDehydrocholesterolsPhosphatesNutrition PolicyDouble-Blind MethodCholestenesIntestinal AbsorptionHypercalcemiaOsteoporosisAfrican AmericansAlkaline PhosphataseBody Mass IndexRadioimmunoassayAbsorptiometry, PhotonFractures, BoneTandem Mass SpectrometryHyperparathyroidism, SecondaryBostonPostmenopauseOsteocalcinUnited StatesHypocalcemiaMass SpectrometryChromatography, LiquidMilkPyridoxineMineralsAdrenodoxinVitamin K 2PregnancyNebraskaLogistic ModelsHyperparathyroidismMultivariate AnalysisSpectrophotometry, UltravioletOdds RatioDose-Response Relationship, DrugChickensFat SubstitutesParathyroid GlandsMongoliaTime Factors