Two regimens , each represented by one large trial , which showed limited evidence of efficacy in reducing the incidence of hip or other appendicular skeleton fractures were : 1 ) Oral Vitamin D when accompanied by calcium supplementation .
2 ) 1,25 dihydroxy Vitamin D ( calcitriol ) .
This appeared more effective than calcium in a direct comparison .
Hypercalcaemia and gastro-intestinal symptoms , reported in less than 5 % of participants , were slightly more common when Vitamin D analogues were taken .
However , the risk of death was marginally less .
REVIEW ER 'S CONCLUSIONS Uncertainty remains about the efficacy of regimens which include Vitamin D or its analogues in fracture prevention .
Particularly if co-supplementation of calcium is required , significant cost differences are likely to exist between regimens .
BACKGROUND Due to their known effects on bone metabolism , Vitamin D and related compounds have been proposed for the prevention of osteoporosis and fractures .
OBJECTIVES To determine the effects of supplementation with Vitamin D or a Vitamin D analogue in the prevention of fractures of the axial and appendicular skeleton in elderly men or women with involutional or post-menopausal osteoporosis .
The Effect of Season and Vitamin D Supplementation on Bone Mineral Density in Healthy Women: A Double-Masked Crossover Study

Abstract : Vitamin D status is known to be an important determinant of bone mineral density ( BMD ) . There is a significant seasonal variation in serum vitamin D , and some studies have reported an associated seasonal variation in BMD . The present study was devised to investigate whether a seasonal variation in BMD could be detected in healthy normal subjects , along with associated variations in serum parathyroid hormone ( PTH ) , intestinal calcium absorption and biochemical markers of bone turnover . A second aim was to investigate whether , if such variations were identified , they could be suppressed by vitamin D supplementation . The subjects were 70 healthy female volunteers ( mean age 47.2 years , range 24–70 years ) recruited into a double-masked crossover study and followed over 2 years . During the first year 35 subjects received a daily oral supplement containing 800 IU ( 20 mg ) cholecalciferol ( group 1 ) and 35 subjects received a placebo preparation ( group 2 ) . During the second year the treatment each group received was reversed . Lumbar spine ( L1–L4 ) , left proximal femur and total body BMD were measured by DXA at 3-month intervals . Serum 25-hydroxyvitamin D ( 25-OHD ) , serum PTH , bone markers ( bone-specific ALP ( BSAP ) and urinary crosslinks ( DYPD/creatinine ) ) and calcium absorption were also measured at each visit . Cholecalciferol treatment increased serum 25-OHD by 25.4 nmol/l ( p < 0.001 ) , while a reciprocal decrease in serum PTH of 6.6 ng/l ( p = 0.011 ) was seen in subjects in the lowest quartile of baseline serum 25-OHD . The treatment had no significant effect on spine , femur or total body BMD , calcium absorption or bone markers . When Fourier analysis was used to analyze the data for seasonal effect ( defined as twice the amplitude of the 1-year period variation ) a highly significant effect for 25-OHD of 18 nmol/l ( p < 0.001 ) was found . However , no effect was found for BMD , PTH , calcium absorption or bone markers . The analysis set a 95 % confidence limit to the seasonal effect of less than 0.6 % for spine , total hip and total body BMD . It was concluded that in the population of healthy women studied there was no evidence of seasonal variation in spine , femur or total body BMD , serum PTH , calcium absorption or bone markers .  Vitamin D supplementation was found to have no effect on BMD
Two regimens , each represented by one large trial , which showed limited evidence of efficacy in reducing the incidence of hip or other appendicular skeleton fractures were : 1 ) Oral Vitamin D when accompanied by calcium supplementation .
2 ) 1,25 dihydroxy Vitamin D ( calcitriol ) .
This appeared more effective than calcium in a direct comparison .
Hypercalcaemia and gastro-intestinal symptoms , reported in less than 5 % of participants , were slightly more common when Vitamin D analogues were taken .
However , the risk of death was marginally less .
REVIEW ER 'S CONCLUSIONS Uncertainty remains about the efficacy of regimens which include Vitamin D or its analogues in fracture prevention .
Particularly if co-supplementation of calcium is required , significant cost differences are likely to exist between regimens .
BACKGROUND Due to their known effects on bone metabolism , Vitamin D and related compounds have been proposed for the prevention of osteoporosis and fractures .
OBJECTIVES To determine the effects of supplementation with Vitamin D or a Vitamin D analogue in the prevention of fractures of the axial and appendicular skeleton in elderly men or women with involutional or post-menopausal osteoporosis .