Calcium or vitamin D supplementation: should we not support the routine use?

We read with great interest the article published in Journal of the American Medical Association (JAMA) by Zhao et al. (1). In this paper, the authors reported a systematic review and meta-analysis on the association between calcium or vitamin D supplementation and fracture incidence in community-dwelling elderly individuals. They concluded that their findings did not support the routine use of these supplements in community-dwelling elderly individuals.

In the paper, information was lacking on whether the participants were diagnosed with osteoporosis, osteopenia, or had normal bone mass. This lack of information could be a confounding factor, leading to a lack of comparability and reliability of the results. For instance, if most of the subjects in the two groups coincidentally had normal bone mass, the use of calcium or vitamin D supplementation would obviously not contribute to a decrease in fracture risk. As another example, if subjects in the case groups were infinitely close to those with osteoporosis with regard to their bone mass, and the subjects of the control groups were infinitely close to those with normal bone mass, the results might suggest that the use of calcium or vitamin D supplementation increased the risk of fractures, since calcium or vitamin D supplementation was a singe aspect of the anti-osteoporosis drug therapy. Therefore, information regarding the characteristics of the subjects is vital to ensure that the conclusions can be properly inferred.

The subjects in the study were mainly from Europe and America. As we know, European and American people spend more time doing outdoor sports compared to those in other parts of the world, thereby increasing their exposure to sunshine. Both exercise and sunlight could contribute to protection against osteoporosis (2,3). Undoubtedly, including participants from different global areas would inevitably influence the veracity of the results in the meta-analysis.

It is recommended in osteoporosis prevention and treatment guidelines (4,5) that treatment should include drugs that both suppress the absorption of bone and promote the formation of bone, in addition to Vitamin D and calcium supplementation. We hypothesize that the use of calcium and vitamin D, without other drugs, does not decrease the risk of fractures, similar to what the authors have concluded. Can we be sure that calcium and vitamin D do not play a role when they are used with other drugs like bisphosphonate or teriparatide? If not, we cannot deny the effect of them.

Given the above, the clinical significance of the paper for preventing fractures would be controversial.

Acknowledgments

Funding: This study was supported by grants from Science and Technology Program of Zhejiang Province through the Department of Science and Technology of Zhejiang Province (2017C37119).

Footnote

Provenance and Peer Review: This article was a standard submission to the journal. The article has undergone external peer review.

Conflicts of Interest: Both authors have completed the ICMJE uniform disclosure form (available at http://dx.doi.org/10.21037/aoj.2018.09.09). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Zhao JG, Zeng XT, Wang J, et al. Association Between Calcium or Vitamin D Supplementation and Fracture Incidence in Community-Dwelling Older Adults: A Systematic Review and Meta-analysis. JAMA 2017;318:2466-82. [Crossref] [PubMed]
2. Watson SL, Weeks BK, Weis LJ, et al. High-Intensity Resistance and Impact Training Improves Bone Mineral Density and Physical Function in Postmeno-pausal Women With Osteopenia and Osteoporosis: The LIFTMOR Randomized Controlled Trial. J Bone Miner Res 2018;33:211-20. [Crossref] [PubMed]
3. Santos L, Elliott-Sale KJ, Sale C, et al. Exercise and bone health across the lifespan. Biogerontology 2017;18:931-46. [Crossref] [PubMed]
4. Moyer VA. Vitamin D and calcium supplementation to prevent fractures in adults: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med 2013;158:691-6. [Crossref] [PubMed]
5. Khosla S, Hofbauer LC. Osteoporosis treatment: recent developments and ongoing challenges. Lancet Diabetes Endocrinol 2017;5:898-907. [Crossref] [PubMed]