Daily supplements of calcium and vitamin D significantly reduce the risk of fracture, irrespective of age, sex, or previous fractures, concludes a study published on bmj.com today.
However, for vitamin D supplements alone, no significant effects were found.
Fragility fractures are a major cause of illness in older people and a considerable burden to health services, yet conflicting evidence exists on the role of vitamin D, either alone or in combination with calcium, in reducing fractures. Some studies have shown a reduction in the risk of fractures, others have shown no effect, and one recent study found an increased risk of hip fracture.
The best dose to use, which patients benefit most, and which fractures are most amenable to such treatment remain a clinical dilemma.
So a team of researchers based at Gentofte Hospital in Copenhagen and the University of Southern Denmark analysed data from seven large trials to assess the effectiveness of vitamin D or vitamin D plus calcium in reducing fractures among 68,517 older people (average age 70 years). The study also involved collaborators in the UK, Norway and the Women's Health Initiative in the US.
They found that vitamin D given alone in doses of 10-20 ìg/day is not effective in preventing fractures.
By contrast, calcium and vitamin D given together reduce hip fractures and total fractures, and probably vertebral fractures, irrespective of age, sex, or previous fractures.
The authors emphasise that their analysis does not allow for a direct comparison of vitamin D against vitamin D given with calcium, but only comparisons between each intervention and no treatment. Additional studies of vitamin D are also needed, especially trials of vitamin D given daily at higher doses without calcium, they conclude.
Although the evidence is still confusing, there is growing consensus that combined calcium and vitamin D is more effective than vitamin D alone in reducing non-vertebral fractures, says Professor Opinder Sahota from Queen's Medical Centre, Nottingham in an accompanying editorial. Further studies are needed to define the optimal dose, duration, route of administration, and dose of the calcium combination.