With the world in the grip of the COVID-19 pandemic, public health measures that could reduce the risk of infection and death along with less quarantines are desperately needed. Vitamin D supplementation shows promise in reducing those risks in both the COVID-19 virus and influenza.
Through a variety of mechanisms, Vitamin D can reduce the risk of infections. These mechanisms include inducing defensins and cathelicidins which are both cysteine rich cationic proteins that play a critical role in mammalian innate immune defense against invasive bacterial infections. These proteins can lower viral replication rates and reduce concentrations of pro-inflammatory cytokines that produce the inflammation that injures the lining of the lungs and leads to pneumonia as well as increasing concentrations of anti-inflammatory cytokines.
Vitamin D is a modulator of adaptive immunity. It suppresses responses mediated by the T help cell type by primarily repressing production of inflammatory cytokines. Serum concentrations tend to decrease with age which may be critical to COVID-19 because case fatality rates increase with age.
Several clinical trials and observational studies have reported that Vitamin D supplementation reduced the risk of influenza, whereas others did not. Evidence supporting the role Vitamin D may play in reducing the risk of COVID-19 includes that the outbreak occurred in winter which is a time when
25-hydroxyvitamin D (25(OH)D) concentrations are at their lowest. The number of cases in the Southern Hemisphere near the end of summer are low. Additionally it has been found that Vitamin D deficiency has been found to contribute to acute respiratory distress syndrome and that case fatality rates increase with age and with chronic disease comorbidity both of which are associated with lower (25(OH)D) concentration.
To minimize the risk of infection, it is recommended that people who are at risk of influenza and/or COVID-19 consider taking 10,000 IU/d of Vitamin D3 for a few weeks to rapidly raise 25(OH)D) levels followed by 5,000 IU/d. The goal is to raise 25(OH)D) concentrations above 40-60 ng/mL. For the treatment of people who have already become infection with COVID-19, higher levels of Vitamin D3 doses could be useful.
Magnesium supplementation is recommended when taking Vitamin D supplements as it helps activate Vitamin D which in turn helps regulate calcium and phosphate homeostasis to influence the growth and maintenance of bones. All enzymes which will metabolize Vitamin D appear to require Magnesium which acts as a cofactor in the enzymatic reactions in the kidneys and liver. The dose of Magnesium should be in the range of 250-500 mg/d along with twice the dose of calcium.
Although some contradictory data exists, available evidence indicates that supplementation with multiple micronutrients with immune supporting roles may modulate immune function and help reduce the risk of infection. Micronutrients with the strongest evidence for immune support are Vitamins D and C along with Zinc.
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