Evidences suggesting a possible role of Vitamin D in COVID 19: The missing link

Abstract

The severe acute respiratory syndrome coronavirus 2 is spreading like wildfire with no specific recommended treatment in sight. While some risk factors such as the presence of comorbidities, old age, and ethnicity have been recognized, not a lot is known about who the virus will strike first or impact more. In this hopeless scenario, exploration of time-tested facts about viral infections, in general, seems to be a sound basis to prop further research upon. The fact that immunity and its various determinants (e.g., micronutrients, sleep, and hygiene) have a crucial role to play in the defense against invading organisms, may be a good starting point for commencing research into these as yet undisclosed territories. Herein, the excellent immunomodulatory, antiviral, and anti-inflammatory roles of Vitamin D necessitate thorough investigation, particularly in COVID-19 perspective. This article reviews mechanisms and evidence suggesting the role Vitamin D plays in people infected by the newly identified COVID-19 virus. For this review, we searched the databases of Medline, PubMed, and Embase. We studied several meta-analyses and randomized controlled trials evaluating the role of Vitamin D in influenza and other contagious viral infections. We also reviewed the circumstantial and anecdotal evidence connecting Vitamin D with COVID-19 emerging recently. Consequently, it seems logical to conclude that the immune-enhancing, antiviral, anti-inflammatory, and lung-protective role of Vitamin D can be potentially lifesaving. Hence, Vitamin D deserves exhaustive exploration through rigorously designed and controlled scientific trials. Using Vitamin D as prophylaxis and/or chemotherapeutic treatment of COVID-19 infection is an approach worth considering. In this regard, mass assessment and subsequent supplementation can be tried, especially considering the mechanistic evidence in respiratory infections, low potential for toxicity, and widespread prevalence of the deficiency of Vitamin D affecting many people worldwide.

Keywords: COVID-19; Vitamin D; prophylaxis; treatment; viral respiratory illness.

Figure 1

Role of Vitamin D in COVID- 19. Severe acute respiratory syndrome coronavirus 2 and low levels of Vitamin D cause a downregulation of angiotensin-converting enzyme-2-dependent angiotensin (1–7) and enhancement of angiotensin-converting enzyme E-mediated angiotensin II levels. Lung injury is consequent to increased pulmonary vasoconstriction, inflammation, oxidative stress, and cytokine storm. These can well be attenuated by adequate levels of Vitamin D that restores a favorable angiotensin-converting enzyme/angiotensin-converting enzyme-2 ratio

Figure 2

Putative mechanisms by which Vitamin D helps in COVID-19