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 .
Effects of Genetic and Nongenetic Factors on Total and Bioavailable 25(OH)D Responses to Vitamin D Supplementation
Context Little is known about how genetic and nongenetic factors modify responses of vitamin D supplementation in nonwhite population s. Objective To investigate factors modifying 25-hydroxyvitamin D [ 25(OH)D ] and bioavailable 25(OH)D [ 25(OH)DBio ] responses after vitamin D3 supplementation . Design , Setting , Participants , and Intervention In this 20-week , r and omized , double-blinded , placebo-controlled trial , 448 Chinese with vitamin D deficiency received 2000 IU/d vitamin D3 or placebo . Main Outcome Measures Serum 25(OH)D , vitamin D-binding protein ( VDBP ) , parathyroid hormone ( PTH ) and calcium were measured , and 25(OH)DBio was calculated based on VDBP levels . Six common polymorphisms in vitamin D metabolism genes were genotyped . Results Between-arm net changes were + 30.6 ± 1.7 nmol/L for 25(OH)D , + 2.7 ± 0.2 nmol/L for 25(OH)DBio , and -5.2 ± 1.2 pg/mL for PTH , corresponding to 70 % [ 95 % confidence interval ( CI ) , 62.8 % to 77.2 % ] net reversion rate for vitamin D deficiency at week 20 ( P < 0.001 ) . Only 25(OH)DBio change was positively associated with calcium change ( P < 0.001 ) . Genetic factors ( GC-rs4588/GC-rs7041 , VDR-rs2228570 , and CYP2R1-rs10741657 ; P ≤ 0.04 ) showed stronger influences on 25(OH)D or 25(OH)DBio responses than nongenetic factors , including baseline value , body mass index , and sex . An inverse association of PTH-25(OH)D was demonstrated only at 25(OH)D of < 50.8 ( 95 % CI , 43.6 to 59.0 ) nmol/L. Conclusions Supplemented 2000 IU/d vitamin D3  raised 25(OH)D and 25(OH)DBio but was unable to correct deficiency in 25 % of Chinese participants , which might be partially attributed to the effect of genetic modification . More studies are needed to eluci date appropriate vitamin D recommendations for Asians and the potential clinical implication s of 25(OH)DBio
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 .