Vitamin D supplementation and COVID‑19 risk: a population‑based, cohort study

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

• • • Regarding COVID‑19 outcomes in calcifediol‑supplemented patients versus propensity score‑matched 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 COVID‑19 outcomes in cholecalciferol‑supplemented patients versus propensity score‑matched 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)

• 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.  

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.

• 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.