Millions of older adults take calcium and vitamin D supplements in the hope of keeping their bones strong and preventing fractures. But a major review suggests these supplements may provide little protection against broken bones and falls for most people.

The review, published in The BMJ, analysed 69 randomised controlled trials involving 153,902 adults. Researchers compared calcium supplements, vitamin D supplements and combinations of both with placebo or no treatment, focusing on whether they reduced fractures and falls.

Supplements Did Little to Prevent Fractures

The researchers found little to no meaningful reduction in the risk of experiencing a fracture among people taking calcium or vitamin D supplements.

For calcium, the conclusion was based on 11 trials involving 9,067 participants and was supported by moderate-certainty evidence. For vitamin D, researchers analysed 36 trials involving 92,045 people and rated the evidence as high certainty.

Taking calcium and vitamin D together produced a similar result. Fifteen trials involving 51,126 participants provided high-certainty evidence that the combination had little to no meaningful effect on fracture prevention.

The supplements also appeared to have little effect on specific outcomes, including hip fractures and falls.

Why Are Calcium and Vitamin D Important?

The findings may seem surprising because both nutrients play important roles in maintaining healthy bones. Calcium is a major structural component of bone, while vitamin D helps the body absorb calcium and supports normal bone metabolism. However, having an important role in the body does not necessarily mean taking additional supplements will prevent fractures in people who already have adequate levels.

The researchers also found that their overall conclusions remained broadly consistent after accounting for factors including age, sex, previous fractures, previous falls, and average calcium intake from food.

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Who Should Not Ignore Medical Advice?

The review does not mean everyone should stop taking calcium or vitamin D. The researchers noted that their conclusions may not apply to people with specific bone disorders or those receiving medication for osteoporosis. The findings may also be less applicable to people at particularly high risk of deficiency or fractures.

Osteoporosis Canada similarly cautions that most of the studies involved independently living older adults who were generally not at high fracture risk and often had normal vitamin D levels. It says the evidence does not directly apply to people living with osteoporosis, those who have experienced a fragility fracture, or people taking osteoporosis medication.

Anyone who has been prescribed supplements for a medical reason should therefore speak with their doctor before changing their treatment.

What Else Can Protect Bone Health?

The findings also highlight the importance of looking beyond supplements when trying to prevent fractures. The review's authors pointed towards strategies such as balance and resistance exercise, which can help improve strength, stability and physical function. Fall-prevention programmes may also combine exercise with assessments of hazards in the home and education tailored to an individual's risk.

Falls are particularly important as people age. Nearly one in three adults aged 65 and older falls each year, according to the review's accompanying report, potentially leading to fractures, pain, loss of independence and reduced quality of life.

The researchers said the evidence does not support routine calcium or vitamin D supplementation specifically to prevent fractures and falls. More research is still needed to determine whether supplements could benefit particular high-risk groups.

For now, maintaining adequate nutrition, staying physically active, and addressing individual risk factors may be more important than assuming a daily supplement alone can protect ageing bones.

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