Vitamin D is a steroid hormone that is created either endogenously by the skin's response to UV radiation or exogenously through food or dietary supplements. Vitamin D deficiency is a global public health issue that affects over a billion individuals at all stages of life. Several studies over the last decade have found a relation between vitamin D deficiency and a variety of disorders, including systemic illness. Vitamin D deficiency affects immunological activities because it has an immunomodulatory effect, enhancing innate immunity through the production of antiviral peptides, and so improving mucosal defenses.
Low levels of serum vitamin D have been linked to acute respiratory tract infections such as epidemic influenza in clinical investigations. Subjects with a blood vitamin D concentration of less than 50 nmol/l, had a 64 percent greater risk of community-acquired pneumonia, according to a recent meta-analysis integrating data from eight observational studies.
Vitamin D deficiency, according to several recent reviews, may impair respiratory immune function, increasing the risk of COVID-19 severity and death. There have also been some retrospective investigations that have found a link between vitamin D levels and the severity of COVID-19 and death.
Can Vitamin D protect against contracting Covid-19?
COVID-19’s outbreak and rapid spread has posed a serious global health risk with uncertain variations. Vitamin D has recently been shown to have antiviral properties, as well as anti-inflammatory and immunomodulatory properties. The infection had appeared to predominantly exploit immune evasion during infection, which is followed by hyperreaction and cytokine storm in some patients, as a known pathogenic pathway in the development of acute respiratory disease syndrome (ARDS).
SARS-CoV-2 enters alveolar and intestinal epithelial cells via using angiotensin-converting enzyme 2 as a host receptor. The renin–angiotensin system may then be dysregulated, resulting in excessive cytokine production and potentially deadly ARDS. Given the disparities in COVID-19 severity and fatality across the globe, it's critical to comprehend the reasons for this. A significant factor could be the improvement of immunity through better nutrition. Vitamin D, for example, plays an important role in immunological function. However, very little is known about vitamin D's involvement in preventing COVID-19 infection and death. According to a study published in the Journal of Infection and Public Health, using data from the COVID-19 pandemic data site for 20 May 2020, this study looked at the relationship between vitamin D levels and COVID-19 cases and deaths per million people in 20 European nations (most countries after peak).
Vitamin D supplementation has been shown to protect against respiratory tract infections in randomised trials and meta-analyses; therefore, people who are at higher risk of vitamin D deficiency during this global pandemic receive advise on taking vitamin D supplements to keep their circulating 25(OH)D at optimal levels (75–125 nmol/L). Some retrospective investigations identified a link between vitamin D and COVID-19 instances and outcomes, whereas others showed no link when confounding variables were taken into account. There is, however, inadequate evidence to link vitamin D levels to COVID-19 severity and death.
To test this idea, specliasts concure that randomised controlled trials and large-scale cohort studies are required.