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 .
Long-term effects of calcium supplementation on serum parathyroid hormone level, bone turnover, and bone loss in elderly women.
We report a 4-year r and omized , double-blind , placebo-controlled clinical trial in 236 normal postmenopausal women ( mean age + /- SE , 66.3+/-0.2 years ) who were r and omized to a calcium ( 1600 mg/day as the citrate ) or placebo group .  The women were seen every 6 months ; 177 completed the trial . Net percentage changes in each group are given relative to baseline . The differences in net percentage changes ( calcium group minus placebo group ) in medians were : for lumbar spine bone density , 2.0 % ( p < 0.001 ) at year 1 and 0.3 % ( not significant ) at year 4 ; for proximal femur bone density , 1.3 % ( p = 0.003 ) at year 1 and 1.3 % ( p = 0.015 ) at year 4 ; and for total body bone mineral , 0.4 % ( p = 0.002 ) at year 1 and 0.9 % ( p = 0.017 ) at year 4 . Similar differences at year 4 were : -18.9 % ( p = 0.002 ) for parathyroid hormone ( PTH ) , -11.9 % ( p = 0.026 ) for serum osteocalcin , and -32.2 % ( p = 0.003 ) for urine free pyridinoline . We conclude that long-term administration of calcium supplements  to elderly women partially reverses age-related increases in serum PTH level and bone resorption and decreases bone loss . However , the effects on bone loss were weaker than those reported for estrogen , bisphosphonates , or calcitonin therapy , indicating that calcium supplements alone can not substitute for these in treating established osteoporosis . Nonetheless , because of their safety , high tolerance , and low expense , calcium supplements may be a useful preventive measure for elderly postmenopausal women whose bone mineral density values are normal for their age
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 .