Research raises questions about vitamin D and calcium supplements for fracture prevention

Calcium, vitamin D, or combined supplements offer little to no clinically meaningful benefit for fracture and fall prevention in older adults with no increase in risk, researchers have suggested.

Based on the findings, the supplements should not be recommended in the general adult population, according to a new in-depth review published in The BMJ.

However, experts stressed the findings do not apply to all patient groups and should not change current osteoporosis guidance in the UK.

The systematic review and meta-analysis analysed data from 69 randomised controlled trials involving nearly 154,000 adults that compared calcium, vitamin D, or combined supplementation with placebo or no treatment.

Most participants were community-dwelling older adults – with a median age of 71 years across the trials – and were not at high risk of fractures or falls. Additionally, no one in the trial was receiving drug treatment for osteoporosis.

The Canadian researchers said they undertook the review to address continued uncertainty around the evidence. They highlighted that despite limited evidence of benefit, vitamin D – with or without calcium – continues to be widely recommended for bone health, with prescribing rising substantially in recent years.

Almost a third of people aged 65 and older, and more than half of care home residents, fall each year, with around 5% resulting in fractures. Falls and fractures are influenced by a range of biological, behavioural, environmental and socioeconomic factors, while low body mass index and low bone density also increase risk.

Because calcium and vitamin D are important for bone metabolism, supplements have long been seen as a simple and inexpensive way to help prevent fractures and falls.

After agreeing on clinically meaningful thresholds, the researchers found little to no effect for experiencing any fracture from use of calcium supplements, vitamin D supplements, or combined supplementation.

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 acknowledged 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.

The researchers noted that their 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, the researchers 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.’

Professor Emma L Duncan, professor of clinical endocrinology at King’s College London, said: ‘The authors showed no significant effect of calcium or vitamin D, individually, on fracture risk or on falls risk. 

‘[Additionally, although] the effect of combined calcium and vitamin D on fracture risk did reach statistical significance, the authors highlight, that the absolute benefit was very small and not considered clinically meaningful; and there was no significant effect of combined calcium and vitamin D for falls risk.’

Professor Duncan added that the paper added valuable information to the discussion around supplementation.

‘Avoiding ineffective treatment – for any condition – is important for everyone, from consumers to prescribers to the health system in general.  This paper will support individuals and their doctors in a more nuanced and personalised approach as to whether calcium and vitamin D will be of individual clinical benefit for that person,’ she said.

‘This paper may also encourage discussion, particularly in individuals who are high risk of fracture, regarding the use of well-established and effective therapeutic options that can meaningfully reduce fracture risk.’

Professor Celia L Gregson, professor of clinical epidemiology at the University of Bristol and a member of the National Osteoporosis Guideline Development Group (NOGG), said: ‘From a NOGG perspective, our guidance doesn’t change. If you have osteoporosis or have had a prior fragility fracture, you are a higher risk group for fracture, and you certainly need enough calcium and vitamin D for bone health.’

According to Dr Lucy Douglas, a GP with a special interest in musculoskeletal, many of the findings in the review were already known.

‘The one advantage I can see in putting this information out there again, is to emphasise that if patients have low bone density, these supplements are not enough to protect them from future fractures. They need proper treatment,’ she said.