"... maintaining the balanced levels of vitamin D3 is highly recommended considering its diverse benefits in our system."
Abstract
SARS-CoV-2 virus, the main culprit for COVID-19 disaster, has triggered a gust of curiosity both in the mechanism of action of this infection as well as potential risk factors for disease generation and regimentation. The prime focus of the present review, which is basically a narrative one, is in utilizing the current concepts of vitamin D3 as an agent with myriad functions, one of them being immunocompetence and a promising weapon for both innate and adaptive immunity against COVID-19 infection. Some of the manifestations of SARS-CoV-2 virus such as Acute Respiratory Distress Syndrome (ARDS) overlap with the pathophysiological effects that are overcome due to already established role of vitamin D3 e.g., amelioration of cytokine outburst. Additionally, the cardiovascular complications due to COVID-19 infection may also be connected to vitamin D3 levels and the activity of its active forms. Eventually, we summarise the clinical, observational and epidemiological data of the respiratory diseases including COVID-19 disease and try to bring its association with the potential role of vitamin D3, in particular, the activity of its active forms, circulating levels and its supplementation, against dissemination of this disease.
Abbreviations: VDR, vitamin D receptor; ROR, retinoid acid-related orphan receptors; AhR, aryl hydrocarbon receptor; ROS, reactive oxygen species; ARDS, acute respiratory distress syndrome; MERS, Middle East respiratory syndrome; GSH, glutathione; LC, l-cysteine; RCT, Randomised Controlled Trial.
Conclusion
The available clinical data is still at the stage of its infancy considering the disease to be the most recent finding, so it is too early to deduce an established association between vitamin D3 and COVID-19 infectious disease. Most of the articles published in this regard are circumstantial, associative, less argumentative and undergoing only limited peer-review process. However, large number of recent manuscripts do support the notion that vitamin D3 deficiency is related to COVID-19 disease. The role that vitamin D3 plays besides its classical actions in immune cells and non-skeletal target tissues would help in extrapolating its role in the severity of this disease and its clinical outcome. At the time of writing this article clinical trials have already been conducted and many more are under way linking the impact of vitamin D3 supplementation and 25(OH)D3 levels on patients with COVID-19 disease. So, until we may find something conclusive it would not be an exaggeration if we state that maintaining the balanced levels of vitamin D3 is highly recommended considering its diverse benefits in our system.