Nutritional Perspectives to Coronavirus Disease 2019 (COVID-19) Susceptibility and Severity: a review of the roles of vitamin D and C

Abstract
Background: Coronavirus disease 2019 (COVID-19) which was declared a global pandemic on March 11,
2020 is known to have affected more than 108 million people with more than 2 million deaths worldwide as at
February 2021. The pathophysiology of disease severity is governed by a cytokine storm which could
potentially be modulated by certain vitamins such as vitamins D and C with immunomodulatory and antiinflammatory properties. The mechanisms underpinning the susceptibility to and severity of the disease when
these nutrients that have shown anti-inflammatory properties are deficient is yet to be fully elucidated.
Objectives: The aim of this review was to explore the plausible mechanisms through which vitamin D and C
can influence risk of SARS-CoV-2 infection and progression to severe symptomatic form of COVID-19.
Method: We performed a literature search to review the pathophysiology of COVID-19 as well as effects of
supplemental vitamin D and C on risk of infection, disease progression and severity.
Results: Randomised control trials which administered high doses of vitamin D and C, have shown
demonstrable beneficial effects in COVID-19 patients. Although there is no recommended dose of vitamin D
and C for COVID-19, maintaining optimum plasma concentration of vitamin D (100-150 nmol/L) and
vitamin C (60-80 µmol/L) may prove beneficial. Doses of 50-125µg/day of vitamin D3 and 2-3g/day of
vitamin C have proven effective in maintaining this optimum plasma concentration in COVID-19.
Conclusions: Together these studies suggest that high dose supplementation of vitamin D and C to maintain
optimum plasma concentration have shown better outcome, reduced risk of progression and fatality even in

severe cases of COVID-19.

KEYWORDS: COVID-19, SARS-CoV-2, Vitamin D, Vitamin C, cytokine storm.