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 .
Does high dose vitamin D supplementation enhance cognition?: A randomized trial in healthy adults
Background Insufficiency of 25‐hydroxyvitamin D [ 25(OH)D ] has been associated with dementia and cognitive decline . However , the effects of vitamin D supplementation on cognition are unclear . It was hypothesized that high dose vitamin D3 supplementation would result in enhanced cognitive functioning , particularly among adults whose 25(OH)D levels were insufficient ( < 75 nmol/L ) at baseline . Methods Healthy adults ( n = 82 ) from northern British Columbia , Canada ( 54 ° north latitude ) with baseline 25(OH)D levels ≤100 nmol/L were r and omized and blinded to High Dose ( 4000 IU/d ) versus Low Dose ( 400 IU/d ) vitamin D3 ( cholecalciferol ) for 18 weeks . Baseline and follow‐up serum 25(OH)D and cognitive performance were assessed and the latter consisted of : Symbol Digit Modalities Test , verbal ( phonemic ) fluency , digit span , and the CANTAB ® computerized battery . Results : There were no significant baseline differences between Low ( n = 40 ) and High ( n = 42 ) dose groups . Serum 25(OH)D increased significantly more in the High Dose ( from 67.2 ± 20 to 130.6 ± 26 nmol/L ) than the Low Dose group ( 60.5 ± 22 to 85.9 ± 16 nmol/L ) , p = 0.0001 . Performance improved in the High Dose group on nonverbal ( visual ) memory , as assessed by the Pattern Recognition Memory task ( PRM ) , from 84.1 ± 14.9 to 88.3 ± 13.2 , p = 0.043 ( d = 0.3 ) and Paired Associates Learning Task , ( PAL ) number of stages completed , from 4.86 ± 0.35 to 4.95 ± 0.22 , p = 0.044 ( d = 0.5 ) , but not in the Low Dose Group . Mixed effects modeling controlling for age , education , sex and baseline performance revealed that the degree of improvement was comparatively greater in the High Dose Group for these tasks , approaching significance : PRM , p = 0.11 ( d = 0.4 ) , PAL , p = 0.058 ( d = 0.4 ) . Among those who had insufficient 25(OH)D ( < 75 nmol/L ) at baseline , the High Dose group ( n = 23 ) improved significantly ( p = 0.005 , d = 0.7 ) and to a comparatively greater degree on the PRM ( p = 0.025 , d = 0.6 ) . Conclusions Nonverbal ( visual ) memory seems to benefit from higher doses of vitamin D supplementation , particularly among those who are insufficient ( < 75 nmol/L ) at baseline , while verbal memory and other cognitive domains do not . These findings are consistent with recent cross‐sectional and longitudinal studies , which have demonstrated significant positive associations between 25(OH)D levels and nonverbal , but not verbal , memory . While our findings require confirmation , they suggest that higher 25(OH)D is particularly important for higher level cognitive functioning , specifically nonverbal ( visual ) memory , which also utilizes executive functioning processes . HighlightsNovel trial of high versus low dose vitamin D3 on multiple cognitive domainsHigh  dose vitamin D ( 4000 IU/d ) improved nonverbal ( visual ) memory after 18 weeks.25(OH)D levels < 75 nmol/L at baseline may confer more benefit with supplementation
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 .