CONCLUSIONS Dietary calcium intake is not associated with risk of fracture , and there is no clinical trial evidence that increasing calcium intake from dietary sources prevents fractures .
OBJECTIVE To examine the evidence underpinning recommendations to increase calcium intake through dietary sources or calcium supplements to prevent fractures .
Women’s Health Initiative clinical trials: interaction of calcium and vitamin D with hormone therapy
Objective This study aims to test the added value of calcium and vitamin D ( CaD ) in fracture prevention among women taking postmenopausal hormone therapy ( HT ) . Methods This is a prospect i ve , partial-factorial , r and omized , controlled , double-blind trial among Women ’s Health Initiative postmenopausal participants aged 50 to 79 years at 40 centers in the United States with a mean follow-up of 7.2 years . A total of 27,347 women were r and omized to HT ( 0.625 mg of conjugated estrogens alone , or 0.625 mg of conjugated equine estrogens plus 2.5 mg of medroxyprogesterone acetate daily ) , and 36,282 women were r and omized to 1,000 mg of elemental calcium ( carbonate ) plus 400 IU of vitamin D3 daily , each compared with placebo .  A total of 16,089 women participated in both arms . The predefined outcomes were adjudicated hip fractures and measured bone mineral density . Results Interaction between HT and CaD on hip fracture ( P interaction = 0.01 ) was shown . The effect of CaD  was stronger among women assigned to HT ( hazard ratio [ HR ] , 0.59 ; 95 % CI , 0.38 - 0.93 ) than among women assigned to placebo ( HR , 1.20 ; 95 % CI , 0.85 - 1.69 ) . The effect of HT on hip fracture was stronger among women assigned to active CaD ( HR , 0.43 ; 95 % CI , 0.28 - 0.66 ) than among women assigned to placebo ( HR , 0.87 ; 95 % CI , 0.60 - 1.26 ) . CaD supplementation enhanced the antifracture effect of HT at all levels of personal calcium intake . There was no interaction between HT and  CaD  on change in hip or spine bone mineral density .  Conclusions Postmenopausal women at normal risk for hip fracture who are on CaD supplementation  experience significantly reduced incident hip fractures beyond HT alone at all levels of personal baseline total calcium intake
CONCLUSIONS Dietary calcium intake is not associated with risk of fracture , and there is no clinical trial evidence that increasing calcium intake from dietary sources prevents fractures .
OBJECTIVE To examine the evidence underpinning recommendations to increase calcium intake through dietary sources or calcium supplements to prevent fractures .