Conclusions and Relevance In this systematic review and meta- analysis , neither intermittent nor daily dosing with st and ard doses of vitamin D alone was associated with reduced risk of fracture , but daily supplementation with both vitamin D and calcium was a more promising strategy
Importance Vitamin D and calcium supplements are recommended for the prevention of fracture , but previous r and omized clinical trials ( RCTs ) have reported conflicting results , with uncertainty about optimal doses and regimens for supplementation and their overall effectiveness .
Objective To assess the risks of fracture associated with differences in concentrations of 25-hydroxyvitamin D ( 25[OH]D ) in observational studies and the risks of fracture associated with supplementation with vitamin D alone or in combination with calcium in RCTs .
Hip bone loss is attenuated with 1000 IU but not 400 IU daily vitamin D3: a 1-year double-blind RCT in postmenopausal women.
Few year-long vitamin D supplementation trials exist that match seasonal changes . The aim of this study was to determine whether daily oral vitamin D3 at 400 IU or 1000 IU compared with placebo affects annual bone mineral density ( BMD ) change in postmenopausal women in a 1-year double-blind placebo controlled trial in Scotl and . White women aged 60 to 70 years ( n = 305 ) were r and omized to one of two doses of vitamin D or placebo . All participants started simultaneously in January/February 2009 , attending visits at bimonthly intervals with 265 ( 87 % ) women attending the final visit and an additional visit 1 month after treatment cessation . BMD ( Lunar iDXA ) and 1,25-dihydroxyvitamin D[1,25(OH)2 D ] , N-terminal propeptide of type 1 collagen [ P1NP ] , C-terminal telopeptide of type I collagen [ CTX ] , and fibroblast growth factor-23 [ FGF23 ] were measured by immunoassay at the start and end of treatment . Circulating PTH , serum Ca , and total 25-hydroxyvitamin D [ 25(OH)D ] ( latter by t and em mass spectrometry ) were measured at each visit . Mean BMD loss at the hip was significantly less for the 1000 IU vitamin D group ( 0.05 % ± 1.46 % ) compared with the 400 IU vitamin D or placebo groups ( 0.57 % ± 1.33 % and 0.60 % ± 1.67 % , respectively ) ( p < 0.05 ) . Mean ( ± SD ) baseline 25(OH)D was 33.8 ± 14.6 nmol/L ; comparative 25(OH)D change for the placebo , 400 IU , and 1000 IU vitamin D groups was -4.1 ± 11.5 nmol/L , + 31.6 ± 19.8 nmol/L , and + 42.6 ± 18.9 nmol/L , respectively . Treatment did not change markers of bone metabolism , except for a small reduction in PTH and an increase in serum calcium ( latter with 1000 IU dose only ) . The discordance between the incremental increase in 25(OH)D between the 400 IU and 1000 IU vitamin D and effect on BMD suggests that 25(OH)D may not accurately reflect clinical outcome , nor how much vitamin D is being stored
Conclusions and Relevance In this systematic review and meta- analysis , neither intermittent nor daily dosing with st and ard doses of vitamin D alone was associated with reduced risk of fracture , but daily supplementation with both vitamin D and calcium was a more promising strategy
Importance Vitamin D and calcium supplements are recommended for the prevention of fracture , but previous r and omized clinical trials ( RCTs ) have reported conflicting results , with uncertainty about optimal doses and regimens for supplementation and their overall effectiveness .
Objective To assess the risks of fracture associated with differences in concentrations of 25-hydroxyvitamin D ( 25[OH]D ) in observational studies and the risks of fracture associated with supplementation with vitamin D alone or in combination with calcium in RCTs .