key: cord-0773013-w2s1bcp6
authors: Hemilä, Harri; Chalker, Elizabeth
title: Vitamin C as a Possible Therapy for COVID-19
date: 2020-05-15
journal: Infect Chemother
DOI: 10.3947/ic.2020.52.2.222
sha: 686e2e2ce2dbcb624dcbdbc396f47bc8ac95d53c
doc_id: 773013
cord_uid: w2s1bcp6

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. We would like to propose that vitamin C should also be included as a possible treatment as it has numerous effects on the immune system [2, 3] .

In a meta-analysis of 29 controlled trials with 11,306 participants, we showed that regular vitamin C intake of around 1 g/day did not prevent upper respiratory tract infections (URTIs) [4] . However, the same trials found that vitamin C shortened and alleviated URTIs that occurred during the period of vitamin C administration. In adults the duration of infections was reduced by 8% and in children by 14% [4] . Given the low frequency and usually mild symptoms of URTIs, and the relatively small benefit, prophylactic daily vitamin C dosing does not seem worthwhile under normal circumstances. However, noting that many URTIs are caused by endemic coronaviruses, there is no reason or evidence to assume that vitamin C would be completely ineffective against COVID-19. Given that COVID-19 is often much more severe than ordinary URTIs, the above estimates might justify a regular increased daily intake of vitamin C while the prevalence of COVID-19 is high.

Furthermore, one of the major causes for concern with COVID-19 is the relatively high proportion of cases requiring intensive care unit (ICU) treatment. A meta-analysis of 12 trials with 1,766 patients in ICU found that vitamin C shortened ICU stay by 8% [5] . Another metaanalysis of eight trials found that vitamin C shortened the duration of mechanical ventilation in patients who required the longest ventilation [6] . There is evidence that vitamin C levels decline dramatically in critically ill patients [5, 7] . Although 0.1 g/day of vitamin C can maintain a normal plasma level in a healthy person [8] , much higher doses (1 -4 g/day) are needed to increase plasma vitamin C levels of critically ill patients to within the normal range [5, 9] . Vitamin C is a safe and inexpensive essential nutrient and therefore investigation of its possible effects on COVID-19 should be encouraged along with the several other potential treatments [1] .

Interim guidelines on antiviral therapy for COVID-19

Vitamin C promotes maturation of T-cells

Vitamin C and immune function nutrients

Vitamin C for preventing and treating the common cold

Vitamin C can shorten the length of stay in the ICU: a meta-analysis

Vitamin C may reduce the duration of mechanical ventilation in critically ill patients: a meta-regression analysis

Hypovitaminosis C and vitamin C deficiency in critically ill patients despite recommended enteral and parenteral intakes

Vitamin C pharmacokinetics in healthy volunteers: evidence for a recommended dietary allowance

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