Prophylactic and Therapeutic Role of Vitamin D Supplementation in COVID-19: A Review

Looking at the current scenario of the global pandemic with Coronavirus Disease 2019 (COVID-19) and the dramatic rise of variant COVID-19 cases it is reasonable to reason that one’s immunity (innate, adaptive, or passive) plays a vital role in an individual’s susceptibility as well as the severity. While the population is getting passively immunized with vaccination, the innate and adaptive immune response should also be emphasized. Vitamins and minerals play an important role in developing and modulating the immune response in the human body. Of which, one is, Vitamin D. Besides playing a major role in Calcium metabolism, Vitamin D is involved in modulating various immune system pathways to contain the virus, which includes dampening Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) entry and replication, reducing pro-inflammatory cytokines and increasing anti-inflammatory cytokines, increasing the synthesis of a natural antimicrobial peptide, and activating protective cells such as macrophages that can kill SARS-CoV-2. Vitamin D also possesses a neuroprotective property that is linked to the modulation of neurotrophins. In the current situation of the pandemic, an important connection between Vitamin D deficiency and poor health outcomes in COVID-19 patients have been reported. Furthermore, adequate Vitamin D levels were linked to a lower risk of unconsciousness and hypoxia. Vitamin D deficiency affects over half of the world's population. A low serum concentration of Vitamin D is a risk factor for acute respiratory tract infection. Vitamin D supplementation, on the other hand, is linked to a reduced risk of acute respiratory tract infections. Here, we conducted a literature review of publicly available information to summarize the link between Vitamin D levels and the severity of COVID-19 infection. The main objective of this manuscript is to review and provide information reported by published literature from publically available papers on online databases regarding the significance of Vitamin D in immune response and its prophylactic and therapeutic role in the management of COVID-19.