VITAMIN D AND RESPIRATORY TRACT INFECTIONS: A NARRATIVE REVIEW OF DEFICIENCY, SUPPLEMENTATION STRATEGIES, AND CLINICAL OUTCOMES

Iga Suchta; Nicole Aleksandra Ordyczyńska-Mardyła; Anna Łęczycka; Kinga Haduch; Zuzanna Michalska; Izabela Zuzanna Stranz; Aleksandra Stańczyk; Olga Helena Chorąży; Joanna Strzelczyk; Amelia Kędziora

doi:10.31435/ijitss.2(50).2026.5528

Authors

Iga Suchta District Hospital in Proszowice, Proszowice, Poland https://orcid.org/0009-0005-5837-5790
Nicole Aleksandra Ordyczyńska-Mardyła District Hospital in Chrzanów, Chrzanów, Poland https://orcid.org/0009-0007-1502-8291
Anna Łęczycka Independent Public Health Care Facility of the Ministry of Internal Affairs and Administration in Gdańsk, Gdańsk, Poland https://orcid.org/0009-0004-9068-5222
Kinga Haduch University Hospital in Kraków, Kraków, Poland https://orcid.org/0009-0004-4853-9395
Zuzanna Michalska Clinical Hospital of the Ministry of Internal Affairs and Administration with the Warmia-Mazury Oncology Centre in Olsztyn, 10-228 Olsztyn, Poland https://orcid.org/0009-0005-8775-102X
Izabela Zuzanna Stranz Ludwik Rydygier Provincial Hospital in Toruń, Toruń, Poland https://orcid.org/0009-0002-3689-0132
Aleksandra Stańczyk Clinical Hospital of the Ministry of Internal Affairs and Administration with the Warmia-Mazury Oncology Centre in Olsztyn, Olsztyn, Poland https://orcid.org/0009-0000-2356-7841
Olga Helena Chorąży Independent Public Healthcare Center Myślenice, Myślenice, Poland https://orcid.org/0009-0001-3094-2299
Joanna Strzelczyk Nicolaus Copernicus Provincial Multispecialty Center for Oncology and Traumatology in Lodz, Łódź, Poland https://orcid.org/0009-0006-8212-9431
Amelia Kędziora University of Warmia and Mazury in Olsztyn, Olsztyn, Poland https://orcid.org/0009-0001-8883-4370

DOI:

https://doi.org/10.31435/ijitss.2(50).2026.5528

Keywords:

Vitamin D; Respiratory Tract Infections; Deficiency; Supplementation; Clinical Outcomes; Public Health

Abstract

Vitamin D is widely recognised for its role in calcium homeostasis and skeletal health, yet its biological relevance extends beyond the musculoskeletal system to immune regulation and host defence. Over the past decade, the relationship between vitamin D status and respiratory tract infections (RTIs) has attracted increasing scientific interest, particularly in the context of the widespread prevalence of vitamin D deficiency and the global impact of the COVID-19 pandemic. This narrative review synthesises evidence on vitamin D deficiency, supplementation strategies, and respiratory clinical outcomes, drawing on randomised controlled trials, systematic reviews, meta-analyses, observational studies, and selected mechanistic publications. The reviewed literature consistently suggests that low serum 25-hydroxyvitamin D [25(OH)D] concentrations are associated with increased susceptibility to RTIs and, in many settings, with poorer respiratory outcomes. However, evidence regarding the benefits of supplementation remains heterogeneous. Earlier meta-analyses suggested modest protective effects, particularly among individuals with lower baseline vitamin D status and in studies using daily or weekly standard-dose regimens, whereas more recent large randomised trials and updated meta-analyses have reported smaller, inconsistent, or statistically non-significant overall effects. These discrepancies likely reflect variation in study population, baseline deficiency, supplementation regimen, trial duration, and outcome definition. Current evidence does not support a universal preventive or therapeutic role of vitamin D supplementation for all RTIs, but it strongly supports the importance of identifying and correcting deficiency, particularly in high-risk groups. From a wider perspective, vitamin D deficiency should also be understood as a socially patterned and potentially modifiable determinant of health, with relevance to prevention, health equity, and public health planning.

References

Bergman, P., Norlin, A.-C., Hansen, S., Rekha, R. S., Agerberth, B., Björkhem-Bergman, L., Ekström, L., Lindh, J. D., & Andersson, J. (2012). Vitamin D3 supplementation in patients with frequent respiratory tract infections: A randomised and double-blind intervention study. BMJ Open, 2(6), Article e001663. https://doi.org/10.1136/bmjopen-2012-001663

Biesalski, H. K. (2020). Vitamin D deficiency and co-morbidities in COVID-19 patients—A fatal relationship? NFS Journal, 20, 10–21. https://doi.org/10.1016/j.nfs.2020.06.001

Camargo, C. A., Jr., Ganmaa, D., Frazier, A. L., Kirchberg, F. F., Stuart, J. J., Kleinman, K., Sumberzul, N., & Rich-Edwards, J. W. (2012). Randomized trial of vitamin D supplementation and risk of acute respiratory infection in Mongolia. Pediatrics, 130(3), e561–e567. https://doi.org/10.1542/peds.2011-3029

Cho, H., Myung, S.-K., & Cho, H.-E. (2022). Efficacy of vitamin D supplements in treatment of acute respiratory infection: A meta-analysis for randomized controlled trials. Nutrients, 14(6), Article 1144. https://doi.org/10.3390/nu14061144

Ginde, A. A., Mansbach, J. M., & Camargo, C. A., Jr. (2009). Association between serum 25-hydroxyvitamin D level and upper respiratory tract infection in the Third National Health and Nutrition Examination Survey. Archives of Internal Medicine, 169(4), 384–390. https://doi.org/10.1001/archinternmed.2008.560

Gombart, A. F., Pierre, A., & Maggini, S. (2020). A review of micronutrients and the immune system—Working in harmony to reduce the risk of infection. Nutrients, 12(1), Article 236. https://doi.org/10.3390/nu12010236

Goodall, E. C., Granados, A. C., Luinstra, K., Pullenayegum, E., Coleman, B. L., Loeb, M., & Smieja, M. (2014). Vitamin D3 and gargling for the prevention of upper respiratory tract infections: A randomized controlled trial. BMC Infectious Diseases, 14, Article 273. https://doi.org/10.1186/1471-2334-14-273

Greiller, C. L., & Martineau, A. R. (2015). Modulation of the immune response to respiratory viruses by vitamin D. Nutrients, 7(6), 4240–4270. https://doi.org/10.3390/nu7064240

Hansdottir, S., Monick, M. M., Hinde, S. L., Lovan, N., Look, D. C., & Hunninghake, G. W. (2008). Respiratory epithelial cells convert inactive vitamin D to its active form: Potential effects on host defense. The Journal of Immunology, 181(10), 7090–7099. https://doi.org/10.4049/jimmunol.181.10.7090

Jia, H., Sheng, F., Yan, Y., Liu, X., & Zeng, B. (2024). Vitamin D supplementation for prevention of acute respiratory infections in older adults: A systematic review and meta-analysis. PLOS ONE, 19(5), Article e0303495. https://doi.org/10.1371/journal.pone.0303495

Jolliffe, D. A., Camargo, C. A., Jr., Sluyter, J. D., Aglipay, M., Aloia, J. F., Ganmaa, D., Bergman, P., Bischoff-Ferrari, H. A., Borzutzky, A., Damsgaard, C. T., Dubnov-Raz, G., Esposito, S., Gilham, C., Ginde, A. A., Golan-Tripto, I., Goodall, E. C., Grant, C. C., Griffiths, C. J., Hibbs, A. M., ... Martineau, A. R. (2021). Vitamin D supplementation to prevent acute respiratory infections: A systematic review and meta-analysis of aggregate data from randomised controlled trials. The Lancet Diabetes & Endocrinology, 9(5), 276–292. https://doi.org/10.1016/S2213-8587(21)00051-6

Jolliffe, D. A., Holt, H., Greenig, M., Talaei, M., Perdek, N., Pfeffer, P., Vivaldi, G., Maltby, S., Symons, J., Barlow, N. L., Normandale, A., Garcha, R., Richter, A. G., Faustini, S. E., Orton, C., Ford, D., Lyons, R. A., Davies, G. A., Kee, F., ... Martineau, A. R. (2022). Effect of a test-and-treat approach to vitamin D supplementation on risk of all cause acute respiratory tract infection and COVID-19: Phase 3 randomised controlled trial (CORONAVIT). BMJ, 378, Article e071230. https://doi.org/10.1136/bmj-2022-071230

Jolliffe, D. A., Camargo, C. A., Jr., Sluyter, J. D., Aglipay, M., Aloia, J. F., Bergman, P., Bischoff-Ferrari, H. A., Borzutzky, A., Bubes, V. Y., Damsgaard, C. T., Ducharme, F. M., Dubnov-Raz, G., Esposito, S., Ganmaa, D., Gilham, C., Ginde, A. A., Golan-Tripto, I., Goodall, E. C., Grant, C. C., ... Martineau, A. R. (2025). Vitamin D supplementation to prevent acute respiratory infections: Systematic review and meta-analysis of stratified aggregate data. The Lancet Diabetes & Endocrinology, 13(4), 307–320. https://doi.org/10.1016/S2213-8587(24)00348-6

Martineau, A. R., Jolliffe, D. A., Hooper, R. L., Greenberg, L., Aloia, J. F., Bergman, P., Dubnov-Raz, G., Esposito, S., Ganmaa, D., Ginde, A. A., Goodall, E. C., Grant, C. C., Griffiths, C. J., Janssens, W., Laaksi, I., Manaseki-Holland, S., Mauger, D. T., Murdoch, D. R., Neale, R., ... Camargo, C. A., Jr. (2017). Vitamin D supplementation to prevent acute respiratory tract infections: Systematic review and meta-analysis of individual participant data. BMJ, 356, Article i6583. https://doi.org/10.1136/bmj.i6583

Murdoch, D. R., Slow, S., Chambers, S. T., Jennings, L. C., Stewart, A. W., Priest, P. C., Florkowski, C. M., Livesey, J. H., Camargo, C. A., Jr., & Scragg, R. (2012). Effect of vitamin D3 supplementation on upper respiratory tract infections in healthy adults: The VIDARIS randomized controlled trial. JAMA, 308(13), 1333–1339. https://doi.org/10.1001/jama.2012.12505

Sha, S., Nguyen, T. M. N., Kuznia, S., Niedermaier, T., Zhu, A., Brenner, H., & Schöttker, B. (2023). Real-world evidence for the effectiveness of vitamin D supplementation in reduction of total and cause-specific mortality. Journal of Internal Medicine, 293(3), 384–397. https://doi.org/10.1111/joim.13578

Urashima, M., Segawa, T., Okazaki, M., Kurihara, M., Wada, Y., & Ida, H. (2010). Randomized trial of vitamin D supplementation to prevent seasonal influenza A in schoolchildren. The American Journal of Clinical Nutrition, 91(5), 1255–1260. https://doi.org/10.3945/ajcn.2009.29094

Vuichard Gysin, D., Dao, D., Gysin, C. M., Lytvyn, L., & Loeb, M. (2016). Effect of vitamin D3 supplementation on respiratory tract infections in healthy individuals: A systematic review and meta-analysis of randomized controlled trials. PLOS ONE, 11(9), Article e0162996. https://doi.org/10.1371/journal.pone.0162996

Wang, C.-H., Porta, L., Yang, T.-K., Wang, Y.-H., Wu, T.-H., Qian, F., Han, Y.-Y., Sheng, W.-H., Chen, S.-C., Lee, C.-C., & Chang, S.-C. (2024). Optimal methods of vitamin D supplementation to prevent acute respiratory infections: A systematic review, dose-response and pairwise meta-analysis of randomized controlled trials. Nutrition Journal, 23, Article 92. https://doi.org/10.1186/s12937-024-00990-w

Wimalawansa, S. J. (2019). Vitamin D deficiency: Effects on oxidative stress, epigenetics, gene regulation, and aging. Biology, 8(2), Article 30. https://doi.org/10.3390/biology8020030

Wimalawansa, S. J. (2025). Vitamin D deficiency meets Hill’s criteria for causation in SARS-CoV-2 susceptibility, complications, and mortality: A systematic review. Nutrients, 17(3), Article 599. https://doi.org/10.3390/nu17030599