Introduction: Amongst the agents proposed to improve bone strength, Vitamin D and its analogues have been the interventions most commonly examined for fracture outcomes.

Results: 19 RCTs have recorded vertebral, hip or other axial fracture outcomes. These trials fall into two main categories - small studies from specialist treatment units with fastidious entry criteria and limited generalisability, and larger community-based studies. The methods of analysing fracture outcome data have frequently included "vertebral fracture rate" which has serious conceptual and statistical limitations. It has been necessary to seek further information from authors of over 80% of trials, with a current response rate of only 20%. Significant heterogeneity exists between trial outcomes for both vertebral and hip fracture.

Discussion: Despite the potential advantages of Vitamin D in terms of cost, it appears premature to recommend its widespread use for primary or secondary fracture prevention.