Subgroup analyses showed that these results were generally consistent regardless of the calcium or vitamin D dose , sex , fracture history , dietary calcium intake , and baseline serum 25-hydroxyvitamin D concentration .
Conclusions and Relevance In this meta- analysis of r and omized clinical trials , the use of supplements that included calcium , vitamin D , or both compared with placebo or no treatment was not associated with a lower risk of fractures  among community-dwelling older adults .
Importance The increased social and economic burdens for osteoporosis-related fractures worldwide make the prevention of such injuries a major public health goal .
Previous studies have reached mixed conclusions regarding the association between calcium , vitamin D , or combined calcium and vitamin D supplements and fracture incidence in older adults .
Objective To investigate whether calcium , vitamin D , or combined calcium and vitamin D supplements are associated with a lower fracture incidence in community-dwelling older adults .
Calcium and vitamin d supplementation in postmenopausal women.
CONTEXT Bone health is influenced by the intake of both calcium and vitamin D. OBJECTIVE Our objective was to evaluate the influence of calcium and vitamin D supplementation on PTH and bone turnover . SETTING , PATIENTS , AND DESIGN : At an ambulatory research center , 159 postmenopausal healthy white women participated in this double-blind , placebo-controlled parallel , longitudinal factorial study that was 6 months in duration . INTERVENTIONS Subjects were r and omly allocated to 4 groups : 1 ) double placebo , 2 ) calcium ( 1200 mg daily ) plus placebo , 3 ) vitamin D3 ( 100 μg ) plus placebo , and 4 ) vitamin D3 and calcium . Serum and urine were collected fasting and 2 hours after a calcium load at baseline and at 3 and 6 months . MAIN OUTCOME MEASURES Serum PTH , cross-linked C-telopeptide ( CTX ) , and procollagen type I N-terminal propeptide ( P1NP ) were measured . RESULTS Before study medication , a calcium load result ed in a decline in PTH and CTX and an increase in urinary calcium excretion . Serum CTX and P1NP declined over time with calcium supplementation but did not change with increased vitamin D intake . There was a decline in PTH in the vitamin D groups in the fasting state compared with placebo . Suppression of PTH was greater after a calcium load in the vitamin D groups . A calcium load decreased PTH and CTX and raised urinary calcium . CONCLUSIONS Fasting PTH  declines with vitamin D supplementation . PTH declines after calcium intake . Supplementation of the diet with 1200 mg calcium/d reduces bone turnover markers , whereas supplementation with up to100 μg vitamin D3/d does not
Subgroup analyses showed that these results were generally consistent regardless of the calcium or vitamin D dose , sex , fracture history , dietary calcium intake , and baseline serum 25-hydroxyvitamin D concentration .
Conclusions and Relevance In this meta- analysis of r and omized clinical trials , the use of supplements that included calcium , vitamin D , or both compared with placebo or no treatment was not associated with a lower risk of fractures  among community-dwelling older adults .
Importance The increased social and economic burdens for osteoporosis-related fractures worldwide make the prevention of such injuries a major public health goal .
Previous studies have reached mixed conclusions regarding the association between calcium , vitamin D , or combined calcium and vitamin D supplements and fracture incidence in older adults .
Objective To investigate whether calcium , vitamin D , or combined calcium and vitamin D supplements are associated with a lower fracture incidence in community-dwelling older adults .