Calcium and vitamin D supplements show limited fracture prevention benefits

Calcium, vitamin D, or combined supplements offer little to no clinically meaningful benefit on fracture and fall prevention in most older people, finds an in-depth review of the latest evidence published by The BMJ today.

Almost a third of people aged 65 and older fall each year, often resulting in fractures, which are linked to pain, reduced quality of life, and the need for residential care. Preventing falls and fractures is therefore a global public health priority. 

Several previous evidence reviews have found no reduction in fractures with either calcium or vitamin D supplements and results are inconsistent for combined use. The benefit of vitamin D on falls also remains unclear. 

Yet despite this, many clinicians, guidelines, and regulatory agencies recommend vitamin D supplements (with or without calcium) for bone health, and prescriptions have increased substantially in recent years. 

To address this uncertainty, researchers in Canada reviewed the results of 69 randomised controlled trials involving 153,902 adults that assessed the effect of calcium or vitamin D supplements - or a combination of both - on reducing the number of fractures and falls compared with placebo or no treatment. 

The trials were of varying quality, but the researchers were able to assess their risk of bias and certainty of evidence using established tools. 

After agreeing on clinically meaningful thresholds, the researchers found little to no effect for experiencing any fracture from use of calcium supplements (moderate certainty evidence from 11 trials; 9,067 participants), vitamin D supplements (high certainty evidence from 36 trials; 92,045 participants), or combined supplementation (high certainty evidence from 15 trials; 51,126 participants). 

Calcium, vitamin D, or combined supplementation also appeared to have little to no effect on specific fractures, such as hip fractures, or falls, based largely on moderate to high certainty of evidence. 

The researchers acknowledge that some analyses included a small number of trials and participants, so these findings should be interpreted with caution, and results may not apply to individuals with specific bone disorders or to those receiving drug treatment for osteoporosis.

However, the findings were consistent after further analyses to account for differences such as participant age, sex, history of fractures and falls, and average dietary calcium intake, supporting the strength of their conclusions.

As such, they say these findings "do not support routine supplementation with calcium or vitamin D, or combined supplementation to prevent fractures and falls" and they suggest clinicians, guideline panels, and regulatory agencies "should re-evaluate their general recommendations for calcium and vitamin D supplementation in light of current evidence."

Evidence from rigorous and well powered trials is needed to inform recommendations for supplementation in higher risk groups, say researchers in a linked editorial.

In the meantime, they suggest that focus and funding should be redirected towards interventions that have been shown to offer meaningful prevention of falls and falls related injuries, such as balance and resistance exercise, and interventions that combine elements like exercise, hazard assessment or education, tailored to individual risk.