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 .
Serum 25-hydroxyvitamin D and clinical fracture risk in a multiethnic cohort of women: the Women's Health Initiative (WHI).
Low 25-hydroxyvitamin D [ 25(OH)D ] levels have been linked to hip fracture in white women . To study the association of 25(OH)D with risk of fracture in multiethnic women , we performed a nested case-control study within the prospect i ve Women 's Health Initiative ( WHI ) Observational Study . Incident fractures were identified in 381 black , 192 Hispanic , 113 Asian , and 46 Native American women over an average of 8.6 years . A r and om sample of 400 white women who fractured was chosen . One control individual was selected per case and matched on age , race/ethnicity , and blood draw date .  25(OH)D , parathyroid hormone , and vitamin D-binding protein ( DBP )  were measured in fasting baseline serum . Conditional logistic regression models were used to calculate the odds ratio ( OR ) and 95 % CI . In multivariable models , higher 25(OH)D levels compared with levels less than 20 ng/mL were associated with a lower risk of fracture in white women ( 20 to < 30 ng/mL : OR = 0.82 , 95 % CI 0.58 - 1.16 ; ≤30.0 ng/mL : OR = 0.56 , 95 % CI 0.35 - 0.90 ; p trend = 0.02 ) . In contrast , higher 25(OH)D ( ≥20 ng/mL ) compared with levels less than 20 ng/mL were associated with a higher risk of fracture in black women ( OR = 1.45 , 95 % CI 1.06 - 1.98 ; p trend = 0.043 ) . Higher 25(OH)D ( ≥30.0 ng/mL ) was associated with higher fracture risk in Asian women after adjusting for DBP ( OR = 2.78 , 95 % CI 0.99 - 7.80 ; p trend = 0.04 ) . There was no association between 25(OH)D and fracture in Hispanic or Native American women . Our results suggest divergent associations between 25(OH)D and fracture by race/ethnicity . The optimal level of 25(OH)D for skeletal health may differ in white and black women
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 .