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 supplements for the prevention of colorectal adenomas. Calcium Polyp Prevention Study Group.
BACKGROUND AND METHODS Laboratory , clinical , and epidemiologic evidence suggests that calcium may help prevent colorectal adenomas . We conducted a r and omized , double-blind trial of the effect of supplementation with calcium carbonate on the recurrence of colorectal adenomas . We r and omly assigned 930 subjects ( mean age , 61 years ; 72 percent men ) with a recent history of colorectal adenomas to receive either calcium carbonate ( 3 g [ 1200 mg of elemental calcium ] daily ) or placebo , with follow-up colonoscopies one and four years after the qualifying examination . The primary end point was the proportion of subjects in whom at least one adenoma was detected after the first follow-up endoscopy but up to ( and including ) the second follow-up examination . Risk ratios for the recurrence of adenomas were adjusted for age , sex , lifetime number of adenomas before the study , clinical center , and length of the surveillance period . RESULTS The subjects in the calcium group had a lower risk of recurrent adenomas . Among the 913 subjects who underwent at least one study colonoscopy , the adjusted risk ratio for any recurrence of adenoma with calcium as compared with placebo was 0.85 ( 95 percent confidence interval , 0.74 to 0.98 ; P=0.03 ) . The main analysis was based on the 832 subjects ( 409 in the calcium group and 423 in the placebo group ) who completed both follow-up examinations . At least one adenoma was diagnosed between the first and second follow-up endoscopies in 127 subjects in the calcium group ( 31 percent ) and 159 subjects in the placebo group ( 38 percent ) ; the adjusted risk ratio was 0.81 ( 95 percent confidence interval , 0.67 to 0.99 ; P=0.04 ) . The adjusted ratio of the average number of adenomas in the calcium group to that in the placebo group was 0.76 ( 95 percent confidence interval , 0.60 to 0.96 ; P=0.02 ) . The effect of calcium was independent of initial dietary fat and calcium intake . CONCLUSIONS Calcium supplementation is associated with a significant - though moderate - reduction in the risk of recurrent colorectal adenomas
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 .