For hip fracture , at a 15 % relative risk , the effect estimate lay between the futility boundary and the inferior boundary , meaning there is reliable evidence that vitamin D supplementation does not reduce hip fractures by this amount , but uncertainty remains as to whether it might increase hip fractures .
The effect estimate lay within the futility boundary at thresholds of 0·5 % for total hip , forearm , and total body bone mineral density , and 1·0 % for lumbar spine and femoral neck , providing reliable evidence that vitamin D does not alter these outcomes by these amounts .
INTERPRETATION Our findings suggest that vitamin D supplementation does not prevent fractures or falls , or have clinical ly meaningful effects on bone mineral density .
There were no differences between the effects of higher and lower doses of vitamin D. There is little justification to use vitamin D supplements to maintain or improve musculoskeletal health .
BACKGROUND The effects of vitamin D on fractures , falls , and bone mineral density are uncertain , particularly for high vitamin D doses .
We aim ed to determine the effect of vitamin D supplementation on fractures , falls , and bone density .
Effect of vitamin D supplementation on wintertime and overall bone loss in healthy postmenopausal women.
OBJECTIVES To determine whether relative vitamin D deficiency during the winter months contributes to age-related bone loss  and whether rates of change in hard- and soft-tissue mass vary during the year . DESIGN Double-blind , placebo-controlled , 1-year trial in 249 women in which equal numbers of women were r and omized to either placebo or 400 IU of vitamin D daily . All women received 377 mg/d of supplemental calcium largely as calcium citrate malate . PATIENTS Healthy , ambulatory postmenopausal women with usual intakes of vitamin D of 100 IU/d . MEASUREMENTS Duplicate spine and whole-body scans were done by dual energy x-ray absorptiometry at 6-month intervals that were timed to periods when 25-hydroxyvitamin D levels were highest and lowest . Period 1 was June-July to December-January and period 2 was December-January to the next June-July . Serum parathyroid hormone and plasma 25-hydroxyvitamin D levels were measured during periods 1 and 2 . MAIN RESULTS In the placebo group , spinal bone mineral density increased in period 1 , decreased in period 2 , and sustained no net change . Women treated with vitamin D had a similar spinal increase in period 1 ( 1.46 % compared with 1.40 % in placebo ) , less loss in period 2 ( -0.54 % compared with -1.22 % , CI for the difference , 0.05 % to 1.31 % , P = 0.032 ) and a significant overall benefit ( 0.85 % compared with 0.15 % , CI for the difference , 0.03 % to 1.37 % , P = 0.04 ) . In period 2 , 25-hydroxyvitamin D levels were lower and parathyroid hormone levels were higher in the placebo than in the vitamin D group . Whole-body lean and fat tissue and bone mineral density varied during the year but did not change overall . CONCLUSIONS At latitude 42 degrees , healthy postmenopausal women with vitamin D intakes of 100 IU daily can significantly reduce late wintertime bone loss and improve net bone density of the spine over one year by increasing their intake of vitamin D to 500 IU daily . A long-term benefit of preventing vitamin D insufficiency in the winter seems likely although it remains to be shown . Observed changes in bone as well as in fat and lean tissue appear to be related to season
For hip fracture , at a 15 % relative risk , the effect estimate lay between the futility boundary and the inferior boundary , meaning there is reliable evidence that vitamin D supplementation does not reduce hip fractures by this amount , but uncertainty remains as to whether it might increase hip fractures .
The effect estimate lay within the futility boundary at thresholds of 0·5 % for total hip , forearm , and total body bone mineral density , and 1·0 % for lumbar spine and femoral neck , providing reliable evidence that vitamin D does not alter these outcomes by these amounts .
INTERPRETATION Our findings suggest that vitamin D supplementation does not prevent fractures or falls , or have clinical ly meaningful effects on bone mineral density .
There were no differences between the effects of higher and lower doses of vitamin D. There is little justification to use vitamin D supplements to maintain or improve musculoskeletal health .
BACKGROUND The effects of vitamin D on fractures , falls , and bone mineral density are uncertain , particularly for high vitamin D doses .
We aim ed to determine the effect of vitamin D supplementation on fractures , falls , and bone density .