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 .
Effect of vitamin D replacement on indexes of insulin resistance in overweight elderly individuals: a randomized controlled trial.
BACKGROUND It is unclear whether and at what dose vitamin D supplementation affects insulin resistance ( IR ) . OBJECTIVE We sought to investigate whether vitamin D at doses higher than currently recommended decreases indexes of IR in an ambulatory population of overweight elderly subjects . DESIGN This double-blind , r and omized , controlled multicenter trial enrolled 257 elderly overweight individuals aged ≥65 y with baseline 25-hydroxyvitamin D [ 25(OH)D ] concentrations between 10 and 30 ng/mL. All subjects received 1000 mg calcium citrate/d , with vitamin D administered weekly at an equivalent dose of 600 or 3750 IU/d . The homeostasis model assessment ( HOMA ) of IR index at 1 y was the primary outcome . We also assessed the McAuley index . RESULTS In total , 222 subjects ( 55 % women ) with a mean ± SD age and body mass index ( BMI ; in kg/m(2 ) ) of 71 ± 4 y and 30 ± 4 , respectively , completed the study . Subjects ' baseline characteristics , including IR indexes , were similar across groups : 69 % had prediabetes , 54 % had hypertension ( 47 % were taking antihypertensive medications ) , and 60 % had hyperlipidemia , nearly half of whom were receiving lipid-lowering drugs . At 1 y , mean ± SD serum 25(OH)D increased from 20 ± 7 to 26 ± 7 ng/mL in the low-dose arm ( P < 0.0001 ) and from 21 ± 8 to 36 ± 10 ng/mL in the high-dose arm ( P < 0.001 ) . Median HOMA-IR indexes did not change compared with baseline concentrations and were similar in the high- [ 2.2 ( IQR : 1.5 , 2.9 ) ] and low-dose [ 2.3 ( IQR : 1.6 , 3.3 ] treatment groups . Adjusted analyses showed that HOMA-IR was predicted by the baseline HOMA index and BMI but not by vitamin D dose , baseline serum 25(OH)D , or change in 25(OH)D.  CONCLUSION Vitamin D3 at 3750 IU/d did not improve HOMA-IR compared with the Institute of Medicine Recommended Dietary Allowance of 600 IU/d in elderly overweight individuals . This trial was registered at clinical trials.gov as NCT01315366
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 .