For calcium alone, the finding of little to no effect was based on moderate-certainty evidence from 11 trials involving 9,067 participants — a smaller evidence base.

The same pattern held when researchers looked at specific outcomes such as hip fractures and falls. Most of that evidence was rated moderate to high certainty.

The results also stayed broadly consistent when the researchers accounted for age, sex, previous fractures, previous falls, and average calcium intake from food. That consistency strengthened the team's confidence in the overall conclusions.

What are the study's limitations?

The researchers themselves flag several caveats. Some parts of the analysis drew on relatively small numbers of trials or participants, and those findings deserve careful interpretation.

The conclusions also may not apply to everyone. People with certain bone disorders, or those taking medication for osteoporosis, may have different needs and should not assume these findings apply directly to them. The trials tested supplements for prevention in the general older population, not as treatment for diagnosed conditions.

The studies varied in quality, although the team formally assessed bias and evidence certainty to account for this.

What should change in medical advice?

The researchers state plainly that the evidence "does not support routine supplementation with calcium or vitamin D, or combined supplementation to prevent fractures and falls."

They also argue that clinicians, guideline panels, and regulatory agencies "should re-evaluate their general recommendations for calcium and vitamin D supplementation in light of current evidence." That is a notable statement, given that prescriptions for these supplements have risen substantially in recent years.

Researchers writing in a linked editorial add a caution: more rigorous, well-powered trials are still needed to determine whether supplementation might help people at especially high risk of fractures or falls.

What works better than supplements?

The editorial authors suggest shifting attention and funding toward approaches that have already shown meaningful benefits. Balance training and resistance exercise, for example, improve strength, stability, and physical function — factors directly tied to fall risk.

Programs that combine several strategies may work best. These include:

• Balance and resistance exercise
• Assessment of hazards in the home that could contribute to falls
• Education tailored to a person's individual risk

The biology behind the supplements is not in dispute. Calcium is a major structural component of bone, and vitamin D helps the body absorb it and supports normal bone metabolism. But biology suggesting a plausible mechanism is not the same as evidence that pills prevent broken bones — and previous reviews had already found that calcium or vitamin D alone does not reduce fracture risk, with less consistent results for the combination.

This new analysis, larger and more systematic than most of its predecessors, closes much of that remaining uncertainty.

The bottom line for most older adults: preventing falls and fractures likely requires more than adding a daily supplement to your routine. Structured exercise programs, home safety, and individualized risk assessment appear to offer a more meaningful path — and anyone with a diagnosed bone condition or osteoporosis treatment should discuss their specific needs with a doctor before changing their regimen.