Several studies have shown that vitamin-D could enhance innate and adaptive immunity. It could improve macrophages and dendritic cell function improving the overall immune response. It has also been suggested that inadequate levels of vitamin-D could be a risk for acute respiratory tract diseases. Researchers from Brazil conducted a study to determine if vitamin-D3 supplementation could reduce the length of hospital stay. In this multicenter, double-blind, randomized study, 240 patients with severe COVID-19 were included.
The patients either received a single oral dose of vitamin-D3 200,000 IU or a placebo. The outcomes were mortality, ventilation requirement, ICU admissions, etc. The outcomes also included lab levels of D-dimer, CRP, etc. The results revealed that the supplementation markedly increased the serum 25-hydroxyvitamin D levels as compared to a placebo. The supplementation increased the serum vitamin-D levels by 86.7%. There were no changes in any health-related laboratory parameters following vitamin-D3 supplementation. The researchers concluded that no clinically relevant effects of vitamin-D supplementation were found in severe COVID-19 patients.
Ref link: https://www.medrxiv.org/content/10.1101/2020.11.16.20232397v