Need for additional calcium to reduce the risk of hip fracture with vitamin d supplementation: evidence from a comparative metaanalysis of randomized controlled trials

J Clin Endocrinol Metab. 2007 Apr;92(4):1415-23. doi: 10.1210/jc.2006-1404. Epub 2007 Jan 30.


Purpose: The purpose of this study was to extend the metaanalysis of Bischoff-Ferrari et al., which found that 700-800 IU/d vitamin D reduced hip fracture risk in elderly individuals by 25%, by defining the need for additional calcium supplementation in individuals receiving vitamin D for the prevention of hip fractures.

Data sources: MEDLINE and (search terms: "vitamin D" and "hip fracture"), bibliographies of articles retrieved, and the authors' reference files were used as data sources.

Study selection: Selected studies were randomized controlled trials (RCTs) of oral vitamin D with or without calcium supplementation vs. placebo/no treatment in postmenopausal women and/or older men (>or=50 yr) specifically reporting a risk of hip fracture.

Data extraction: Independent extraction was performed by two authors using predefined criteria, including study quality indicators.

Data synthesis: All pooled analyses are based on random-effects models. Based on four RCTs (9083 patients), the pooled relative risk (RR) of hip fracture for vitamin D alone was 1.10 [95% confidence intervals (CI) 0.89, 1.36]. No between-trial heterogeneity was observed. For the six RCTs (45,509 patients) of vitamin D with calcium supplementation, the pooled RR for hip fracture was 0.82 (95% CI 0.71, 0.94). There was no heterogeneity between trials. In an adjusted indirect comparison of the summary RRs from the two metaanalyses, the RR for hip fracture for vitamin D with calcium vs. vitamin D alone was 0.75 (95% CI 0.58, 0.96).

Conclusions: Our analyses, designed to extend the findings of Bischoff-Ferrari et al., suggest that oral vitamin D appears to reduce the risk of hip fractures only when calcium supplementation is added.

Publication types

  • Meta-Analysis
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Calcium / therapeutic use*
  • Dietary Supplements*
  • Hip Fractures / prevention & control*
  • Humans
  • Middle Aged
  • Osteoporosis
  • Postmenopause
  • Randomized Controlled Trials as Topic
  • Risk
  • Vitamin D / therapeutic use*


  • Vitamin D
  • Calcium