Vitamin D supplementation for the treatment of COVID-19: A systematic review and meta-analysis of randomized controlled trials

• Published in: Frontiers in immunology Vol. 13; p. 1023903
• Main Authors: Kümmel, Lara S., Krumbein, Hanna, Fragkou, Paraskevi C., Hünerbein, Ben L., Reiter, Rieke, Papathanasiou, Konstantinos A., Thölken, Clemens, Weiss, Scott T., Renz, Harald, Skevaki, Chrysanthi
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 31.10.2022
• Subjects: COVID-19; COVID-19 Drug Treatment; Dietary Supplements; Humans; Immunology; meta-analysis; Randomized Controlled Trials as Topic; SARS-CoV-2; systematic review; vitamin D; Vitamin D - therapeutic use; Vitamins - therapeutic use; COVID-19; meta-analysis; SARS-CoV-2; systematic review; vitamin D
• ISSN: 1664-3224; 1664-3224
• DOI: 10.3389/fimmu.2022.1023903

Vitamin D supplementation and its impact on immunoregulation are widely investigated. We aimed to assess the prevention and treatment efficiency of vitamin D supplementation in the context of coronavirus disease 2019 (COVID-19) and any disease-related complications. For this systematic review and meta-analysis, we searched databases (PubMed, Embase, Scopus, Web of Science, The Cochrane Library, medRxiv, Cochrane COVID-19 Study Register, and ClinicalTrial.gov) for studies published between 1 November 2019 and 17 September 2021. We considered randomized trials (RCTs) as potentially eligible when patients were tested for SARS-CoV-2 infection and received vitamin D supplementation versus a placebo or standard-of-care control. A random-effects model was implemented to obtain pooled odds ratios for the effect of vitamin D supplementation on the main outcome of mortality as well as clinical outcomes. We identified a total of 5,733 articles, of which eight RCTs (657 patients) met the eligibility criteria. Although no statistically significant effects were reached, the use of vitamin D supplementation showed a trend for reduced mortality [odds ratio (OR) 0.74, 95% confidence interval (CI) 0.32–1.71, p = 0.48] compared with the control group, with even stronger effects, when vitamin D was administered repeatedly (OR 0.33, 95% CI 0.1–1.14). The mean difference for the length of hospitalization was −0.28 (95% CI −0.60 to 0.04), and the ORs were 0.41 (95% CI 0.15–1.12) and 0.52 (95% CI 0.27–1.02) for ICU admission and mechanical ventilation, respectively. In conclusion, vitamin D supplementation did not improve the clinical outcomes in COVID-19 patients, but trends of beneficial effects were observed. Further investigations are required, especially studies focusing on the daily administration of vitamin D.