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 .
Effects of vitamin D and calcium supplementation on pancreatic β cell function, insulin sensitivity, and glycemia in adults at high risk of diabetes: the Calcium and Vitamin D for Diabetes Mellitus (CaDDM) randomized controlled trial.
BACKGROUND A suboptimal vitamin D and calcium status has been associated with higher risk of type 2 diabetes in observational studies , but evidence from trials is lacking . OBJECTIVE We determined whether vitamin D supplementation , with or without calcium , improved glucose homeostasis in adults at high risk of diabetes . DESIGN Ninety-two adults were r and omly assigned in a 2-by-2 factorial- design , double-masked , placebo-controlled trial to receive either cholecalciferol ( 2000 IU once daily ) or calcium carbonate ( 400 mg twice daily ) for 16 wk . The primary outcome was the change in pancreatic β cell function as measured by the disposition index after an intravenous-glucose-tolerance test . Other outcomes were acute insulin response , insulin sensitivity , and measures of glycemia . RESULTS Participants had a mean age of 57 y , a body mass index ( BMI ; in kg/m(2 ) ) of 32 , and glycated hemoglobin ( Hb A(1c ) ) of 5.9 % . There was no significant vitamin D × calcium interaction on any outcomes . The disposition index increased in the vitamin D group and decreased in the no-vitamin D group ( adjusted mean change ± SE : 300 ± 130 compared with -126 ± 127 , respectively ; P = 0.011 ) , which was explained by an improvement in insulin secretion ( 62 ± 39 compared with -36 ± 37 mU · L(-1 ) · min , respectively ; P = 0.046 ) . Hb A(1c ) increased less , but nonsignificantly , in the vitamin D group than in the no-vitamin D group ( 0.06 ± 0.03 % compared with 0.14 ± 0.03 % , respectively ; P = 0.081 ) . There was no significant difference in any outcomes with calcium compared with no calcium . CONCLUSION In adults at risk of type 2 diabetes , short-term supplementation with cholecalciferol improved β cell function and had a marginal effect on attenuating the rise in Hb A(1c ) . This trial was registered at clinical trials.gov as NCT00436475
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 .