Do vitamin D and calcium really protect your bones?

In May 2026, a Canadian team published in BMJ a review of available evidence on calcium and vitamin D supplementation to prevent fractures and falls in older adults. Researchers analyzed 69 randomized controlled trials involving 153,902 adults. These studies compared food supplements based on calcium, vitamin D or a combination of the two with a placebo or no treatment.

For calcium alone, researchers found little to no reduction in the number of fractures or falls. The same was true for vitamin D taken alone. “Even among studies involving tens of thousands of participants, vitamin D supplementation showed virtually no difference in fracture risk compared to no treatment at all,” Prasad Nishtala, senior lecturer in pharmacoepidemiology at the University of Bath, comments on the website. The Conversation.

When it comes to taking calcium and vitamin D together, this combined supplementation was associated with a slight reduction in certain types of fractures. But these profits remained extremely modest. “For example, the reduction in overall fractures was about one fewer fracture per 100 people taking supplements,” says Dr. Nishtala.

The authors conclude that these results “do not support routine calcium or vitamin D supplementation, separately or in combination, to prevent fractures and falls”. They call on clinicians and health agencies to reevaluate their general recommendations.

Towards personalized supplementation

For Professor Emma Duncan, specialist in clinical endocrinology at King’s College London, the meta-analysis is consistent with previous work. She welcomes the approach of the authors, who favor a personalized approach to supplementation: “This document will help patients and their doctors take a more nuanced and personalized approach to determining whether calcium and vitamin D are of individual clinical benefit to each person. »

The new BMJ meta-analysis confirms a trend that the scientific literature has already been drawing for several years. In The secret to strong bonesThierry Souccar summarizes the state of knowledge as follows: “Studies examining the effects of vitamin D supplementation alone on the risk of fractures in elderly and/or osteoporotic individuals have yielded conflicting results. In several studies, the risk of fractures does not seem to be influenced by taking vitamin D alone. »

On the other hand, the combination of the two micronutrients can have an effect in certain contexts. “Taking supplements combining calcium and vitamin D reduces secondary hyperparathyroidism and reduces the risk of fracture in women aged under 80, an effect particularly marked in those living in retirement homes. » It is precisely these populations, institutionalized, that the meta-analysis of the BMJ excluded from his analysis.

Vitamin D remains useful in case of deficiency

The meta-analysis focuses on elderly people living at home. The authors recognize another weakness of their study: many clinical trials recruited participants who were not at high risk of fractures or falls, and whose baseline vitamin D levels were often normal.

However, as Thierry Souccar explains,“ Vitamin D supplementation can reduce falls when vitamin D is deficient.” For example, a Cochrane review found a 43% reduction in the risk of falls in two studies where participants had low initial vitamin D levels.

In France, nearly 80% of adults have a serum level below 75 nmol/L (threshold considered a sufficient level by theEndocrine Society). Deficiency is even more common in winter in mainland France, because skin synthesis of vitamin D is very low from November to March. Certain populations combine risk factors: people over 60 (whose skin synthesizes less vitamin D than a young person), overweight or obese people (vitamin D remains stored in fat), pigmented skin.

And calcium?

Calcium is the most abundant mineral in the body: 99% is found in the skeleton, where it ensures mineralization and bone rigidity. A deficiency can compromise bone health, but calcium supplements alone do not reduce the risk of fractures. When prescribed by a doctor, calcium citrate is better absorbed than carbonate, especially in people taking proton pump inhibitors.

Food sources of calcium are numerous: dairy products, but also cruciferous vegetables (Chinese cabbage, broccoli, kale), canned sardines, almonds, white beans, tofu, and calcium mineral waters. Among calcium waters, Hépar (555 mg/L), Courmayeur (517 mg/L) or Contrex (468 mg/L) provide substantial contributions.

In practice: how to supplement with vitamin D

The new BMJ meta-analysis argues more for personalized than systematic supplementation. It is therefore preferable to know if you are deficient in vitamin D, by measuring your blood level, before deciding to supplement. In France, the vast majority of adults do not have sufficient levels of vitamin D, especially in winter.

• For supplementation, opt for vitamin D3 which has greater biological activity than D2.
• Daily administration is preferable to high one-time doses.
• As for the doses necessary to maintain a serum level above 30 ng/mL (75 nmol/L), the threshold recommended by the Endocrine Society, they are often higher than the official intakes: between 1,500 and 2,000 IU per day depending on the context, compared to the 600 IU recommended by the French authorities.

To go further: The secret to strong bones

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