Overall , intervention groups obtained higher 25(OH)D concentration than controls and there was obvious dose – response effect between intake dose and 25(OH)D concentration .
Baseline 25(OH)D concentration and age were significant indicators for 25(OH)D concentration .
Conclusions Regional- and age-specific recommended dosages of VitD supplements for population to achieve optimal 25(OH)D concentrations have been suggested
Background / Objectives Optimal doses of vitamin D ( VitD ) supplement in different population s are unclear .
We aim to evaluate the relationship between VitD supplementation and post-intervention serum 25-hydroxyvitamin D [ 25(OH)D ] concentration , to provide a recommended dosage of VitD for achieving an optimal 25(OH)D concentration for different population s .
Estimation of the dietary requirement for vitamin D in adolescents aged 14-18 y: a dose-response, double-blind, randomized placebo-controlled trial.
BACKGROUND Adolescents are a population group at high risk of low vitamin D status , yet the evidence base for establishing dietary vitamin D requirements remains weak . OBJECTIVE The aim was to establish the distribution of  vitamin D intakes required to maintain serum 25-hydroxyvitamin D [ 25(OH)D ] concentrations above proposed cutoffs ( 25 , 30 , 40 , and 50 nmol/L ) during winter in white males and females ( 14 - 18 y of age ) in the United Kingdom ( 51 ° N ) . DESIGN In a dose-response trial , 110 adolescents ( aged 15.9 ± 1.4 y ; 43 % males ) were r and omly assigned to receive 0 , 10 , or 20 μg vitamin D3 supplements/d for 20 wk during winter . A nonlinear regression model was fit to total vitamin D intake and postintervention serum 25(OH)D concentrations , and regression-predicted values estimated the vitamin D intakes required to maintain serum 25(OH)D concentrations above specific cutoffs . RESULTS Mean ± SD serum 25(OH)D concentrations increased from 49.2 ± 12.0 to 56.6 ± 12.4 nmol/L and from 51.7 ± 13.4 to 63.9 ± 10.6 nmol/L in the 10- and 20-μg/d groups , respectively , and decreased in the placebo group from 46.8 ± 11.4 to 30.7 ± 8.6 nmol/L ( all P ≤ 0.001 ) . Vitamin D intakes required to maintain 25(OH)D concentrations > 25 and > 30 nmol/L in 97.5 % of adolescents were estimated to be 10.1 and 13.1 μg/d , respectively , and 6.6 μg/d to maintain 50 % of adolescents at concentrations > 40 nmol/L. Because the response of 25(OH)D reached a plateau at 46 nmol/L , there is uncertainty in estimating the vitamin D intake required to maintain 25(OH)D concentrations > 50 nmol/L in 97.5 % of adolescents , but it exceeded 30 μg/d . CONCLUSION Vitamin D intakes between 10 and ∼30 μg/d are required by white adolescents during winter to maintain serum 25(OH)D concentrations > 25 - 50 nmol/L , depending on the serum 25(OH)D threshold chosen . This trial was registered at clinical trials.gov as NCT02150122 and as International St and ard R and omized Controlled Trial Number IS RCT N40736890
Overall , intervention groups obtained higher 25(OH)D concentration than controls and there was obvious dose – response effect between intake dose and 25(OH)D concentration .
Baseline 25(OH)D concentration and age were significant indicators for 25(OH)D concentration .
Conclusions Regional- and age-specific recommended dosages of VitD supplements for population to achieve optimal 25(OH)D concentrations have been suggested
Background / Objectives Optimal doses of vitamin D ( VitD ) supplement in different population s are unclear .
We aim to evaluate the relationship between VitD supplementation and post-intervention serum 25-hydroxyvitamin D [ 25(OH)D ] concentration , to provide a recommended dosage of VitD for achieving an optimal 25(OH)D concentration for different population s .