Vitamin D is known as the sunshine vitamin as it is synthesized in skin with the help of sunlight. It is primarily involved in bone metabolism. Apart from calcium phosphate homeostasis, it is involved in regulating immunological and inflammatory responses. The immune cells has receptors for vitamin D3. The main culprit of respiratory symptoms in case of SARS-CoV2 is the inflammatory storm induced by the cytokines released after induction of Th1 cells. Vitamin D3 play a very important role by inhibiting the cytokine storm and thus alleviating the pneumonia like symptoms of COVID-19.
Low vitamin D levels are associated with increased cytokine storm, significantly surge in inflammatory reaction. This may lead to development of pneumonia, thrombosis, myocardial infarction in case of corona virus infection. People with sedentary lifestyle, obesity, diabetes have a propensity of low levels of vitamin D putting them at risk of development of serious complications and mortality. The COVID-19 pandemic is an eyeopener to exploit about the multifaceted role of vitamin D to halt the complications and the mortality.
The primary defence mechanism in case of uncontrolled inflammatory viral infection is provided by the T regulatory lymphocytes (Tregs). These levels are low in COVID-19 patients and even markedly low in severe cases. Our motto is to increase the levels of Treg to halt the deleterious effect of corona virus infection.
Vitamin D regulates thrombosis pathway. Its anticoagulant effects help in preventing the blood clots in SARS-CoV2 infection. The widespread micro clot formation in Covid-19 infection leads to multiorgan failure and increased mortality.
Does Vitamin D reduce the cardiovascular risk?
Vitamin D affects the cardiovascular risk like myocardial infarction and hypertension. Optimal concentrations of vitamin D inhibits the renin angiotensin system(RAAS) decreasing the risk of hypertension. Prospective cohort studies show that the 25-hydroxy vitamin D level below 30nmol/l, is independently associated with cardiovascular mortality risk. There is supportive evidence that vitamin D improve overall mortality( Zitterman A et al ).
Ginde A et al showed in a prospective cohort study that serum vitamin D level has an inverse relationship with cardiovascular death and all cause mortality. Randomized control trials of vitamin D supplementation in older adults are necessary to show whether the association is causal and reversible.
Does high dose of vitamin D affect the overall Covid-19 outcome?
Annweiler C et al study shows a single high dose of vitamin D given within 72 hours of diagnosis of covid-19 improves the overall mortality in day 14, in comparison to the standard therapy of vitamin D. It was a multicenter, randomized, controlled open level trial with collaboration of 9 medical centers in France. The admitted patients taken into study were more than 65 years, had SARS CoV-2 positive within 72 hours and had at least one worsening risk factor like age >75 years, SpO2 ≤ 94%, PaO2/FiO2≤ 300mm Hg. Eligible patients were randomized into two groups . They were given a single high dose of 400,000 IU Cholecalciferol or a standard dose of 50,000 IU. In this randomized control trial, it was observed that a single high dose given to elderly patients significantly improved the mortality in the hospital setup in comparison to the standard therapy.
Does Vitamin D has neuroprotective role in COVID-19 ?
Vitamin D prevent loss of neural sensation in Covid-19 by expression of neurotrophins like nerve growth factor(NGF) and also induction of key neurotrophic factors(Xu Yi et al )
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