Originally published by 2 Minute Medicine® (view original article). Reused on AccessMedicine with permission.

1. In this meta-analysis, vitamin D supplementation was associated with reduced ICU admission and mechanical ventilation rates in patients with SARS-CoV-2 infection.

2. However, vitamin D supplementation did not significantly affect mortality associated with SARS-CoV-2 infection.

Evidence Rating Level: 1 (Excellent)

SARS-CoV-2 infection continues to be a life-threatening respiratory illness even three years after the onset of the COVID-19 pandemic. In parallel to the development of vaccines and anti-viral medications, there has also been a growing body of work examining additional disease-modifying therapeutics. Vitamin D has been shown to affect immune cell function, and therefore, there is an interest in investigating whether vitamin D supplementation could play a role in SARS-CoV-2 infections and outcomes. This study sought to review the current evidence to determine if vitamin D supplementation had therapeutic and preventative effects on SARS-CoV-2 infection.

This meta-analysis included 25 randomized controlled trials (n=8,128 participants) published up to April 2023 that evaluated the role of vitamin D supplementation in preventing and treating SARS-CoV-2 infection. Studies were included if they compared the effect of vitamin D supplementation to a control in SARS-CoV-2 infection and reported appropriate outcomes. Studies were excluded if they were not randomized controlled trials or investigated patients with infections other than SARS-CoV-2. The study was conducted according to PRISMA guidelines, and the risk of bias was assessed using the Cochrane Collaboration’s Risk of Bias Tool. The primary outcomes were the rates of ICU admission, mechanical ventilation, and mortality.

The results demonstrated that vitamin D supplementation significantly reduced the rates of ICU admission and mechanical ventilation in patients with SARS-CoV-2 infection. Vitamin D supplementation did not significantly affect other clinical outcomes, including length of hospital stay, mortality, or prevention of SARS-CoV-2 infection. However, in those with vitamin D deficiency, supplementation was associated with decreased mortality. The study was limited by the heterogeneity of the dosing and frequency of vitamin D supplementation and the small number of studies examining the preventative effects of vitamin D. Nonetheless, the present study demonstrated that vitamin D supplementation has beneficial effects on some clinical outcomes in SARS-CoV-2.

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