With the emergence of the COVID-19 pandemic, there is increased interest in vitamin D and its role in supporting innate immune responses to respiratory viruses, including SARS-CoV-2. CITF-funded researcher and member of the CITF Pediatric Network Dr. Jonathon Maguire from University of Toronto, contributed to a systematic review and meta-analysis recently published in The Lancet which aggregated data from 43 randomized controlled trials. The authors showed that vitamin D supplementation was safe and overall reduced the risk of acute respiratory infections compared to a placebo control. The relevance of these findings to the SARS-CoV-2 infection is not yet known and requires further investigation.

 

Building on previous research findings, this meta-analysis of aggregate data from 48,488 participants provides an updated estimate of the protective effects of vitamin D supplementation against acute respiratory infections (ARIs) overall. Furthermore, our funded researcher, Dr. Maguire and colleagues, analyzed whether the effects on ARIs of vitamin D supplementation varied according to dosing regimen (frequency, dose, and trial duration), age at enrolment, or baseline concentration of the 25-Hydroxy Vitamin D in the blood, which is the best indicator of vitamin D status.

Despite evidence of significant heterogeneity across trials, this meta-analysis showed that vitamin D supplementation was safe and overall reduced the risk of ARIs compared to a placebo control, although the risk reduction was small. Protective effects were observed in trials in which vitamin D was given daily in a dose equivalent of 400–1000 IU for a duration of 12 months or less, as well as when vitamin D was given to children aged 1 to 16 years. No significant effect of vitamin D supplementation was observed for any of the subgroups defined by baseline 25-Hydroxy Vitamin D concentration in the blood.

The relevance of these findings to the SARS-CoV-2 infection is not yet known and requires further investigation.

 

Jolliffe DA, Camargo CA Jr, Sluyter JD, Aglipay M, Aloia JF, Ganmaa D, Bergman P, Bischoff-Ferrari HA, Borzutzky A, Damsgaard CT, Dubnov-Raz G, Esposito S, Gilham C, Ginde AA, Golan-Tripto I, Goodall EC, Grant CC, Griffiths CJ, Hibbs AM, Janssens W, Khadilkar AV, Laaksi I, Lee MT, Loeb M, Maguire JL, Majak P, Mauger DT, Manaseki-Holland S, Murdoch DR, Nakashima A, Neale RE, Pham H, Rake C, Rees JR, Rosendahl J, Scragg R, Shah D, Shimizu Y, Simpson-Yap S, Trilok-Kumar G, Urashima M, Martineau AR. Vitamin D supplementation to prevent acute respiratory infections: a systematic review and meta-analysis of aggregate data from randomised controlled trials. Lancet Diabetes Endocrinol. 2021 May;9(5):276-292. doi: 10.1016/S2213-8587(21)00051-6.