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Get summaries of key research on vitamin D and COVID-19

Vitamin D supplementation and COVID19 risk: a populationbased, cohort study

Take Home Message

Supplementation with cholecalciferol or calcifediol helped subject to achieve serum 25OHD levels ≥30 ng/ml which were associated with better COVID-19 outcomes. 


      • Regarding COVID19 outcomes in calcifediolsupplemented patients versus propensity scorematched controls, 5662 patients supplemented with calcifediol were diagnosed with COVID-19 while 11,401 untreated controls were diagnosed. There was no association between calcifediol supplementation and risk of COVID-19 infection or in disease severity or mortality. However, in those with chronic kidney disease, calcifediol supplementation was associated with a significant decrease in COVID-19 infections and a reduced risk of severe COVID-19. For vitamin D levels and COVID-19 risk, vitamin D was significantly greater in patients that developed COVID-19 than in non-infected patients. 
        • For COVID19 outcomes in cholecalciferolsupplemented patients versus propensity scorematched control, COVID-19 infection was diagnosed in 4352 patients supplemented with cholecalciferol and 9142 cases in unsupplemented patients. Vitamin D supplementation was mildly associated with COVID19 infection. . There was no observed associated between supplementation and COVID-19 severity or mortality when comparing to untreated controls. 
    • Patients on cholecalciferol or calcifediol treatment achieving 25OHD levels ≥ 30 ng/ml had lower risk of SARS-CoV2 infection, lower risk of severe COVID-19 and lower COVID-19 mortality than unsupplemented 25OHD-deficient patients.  



Individuals ≥ 18 years old living in Barcelona-Central Catalonia supplemented with cholecalciferol or calcifediol (n = 201,445)

Things to Keep in Mind

  • This is a large study analyzing the association of cholecalciferol or calcifediol supplementation with COVID-19 outcomes at the population level, not just in hospitalized patients. 
  • 400 IU of cholecalciferol was associated with significant, albeit small reductions in the risk of COVID-19. 
  • For the study reviewing supplemented vs. unsupplemented patients, due to seasonal sun exposure, the study only analyzed serum vitamin D levels determined from November 1, 2019, to February 28, 2020.  

Author’s Conclusions

In this large, population-based study, we observed that patients supplemented with cholecalciferol or calcifediol achieving serum 25OHD levels ≥ 30 ng/ml were associated with better COVID-19 outcomes.

Study Design

  • Retrospective, population-based study – three independent studies from data: 
    1. Comparison of COVID outcomes between supplemented patients and propensity score-matched controls 
    1. Association between mean daily cholecalciferol or calcifediol dose and COVID-19 outcomes 
    1. Comparison of COVID-19 outcomes between cholecalciferol or calcifediol-supplemented patients with a sufficient vitamin D status and unsupplemented vitamin D-deficient (<20 ng/dl) patients. 


Oristrell J, Oliva JC, Casado E, Subirana I, Domínguez D, Toloba A, Balado A, Grau M. Vitamin D supplementation and COVID-19 risk: a population-based, cohort study. J Endocrinol Invest. 2022 Jan;45(1):167-179. doi: 10.1007/s40618-021-01639-9. Epub 2021 Jul 17. PMID: 34273098; PMCID: PMC8285728.

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Research Summaries

Association Between Vitamin D Supplementation and COVID-19 Infection and Mortality

Association Between Vitamin D Supplementation and COVID-19 Infection and Mortality Take Home Message Among VA (Veterans Administration) patients, vitamin D3 and vitamin D2 supplementation reduced the associated risk of COVID-19 infection