The Long History of Vitamin C: From Prevention of the Common Cold to Potential Aid in the Treatment of COVID-19

Abstract

From Pauling's theories to the present, considerable understanding has been acquired of both the physiological role of vitamin C and of the impact of vitamin C supplementation on the health. Although it is well known that a balanced diet which satisfies the daily intake of vitamin C positively affects the immune system and reduces susceptibility to infections, available data do not support the theory that oral vitamin C supplements boost immunity. No current clinical recommendations support the possibility of significantly decreasing the risk of respiratory infections by using high-dose supplements of vitamin C in a wellnourished general population. Only in restricted subgroups (e.g., athletes or the military) and in subjects with a low plasma vitamin C concentration a supplementation may be justified. Furthermore, in categories at high risk of infection (i.e., the obese, diabetics, the elderly, etc.), a vitamin C supplementation can modulate inflammation, with potential positive effects on immune response to infections. The impact of an extra oral intake of vitamin C on the duration of a cold and the prevention or treatment of pneumonia is still questioned, while, based on critical illness studies, vitamin C infusion has recently been hypothesized as a treatment for COVID-19 hospitalized patients. In this review, we focused on the effects of vitamin C on immune function, summarizing the most relevant studies from the prevention and treatment of common respiratory diseases to the use of vitamin C in critical illness conditions, with the aim of clarifying its potential application during an acute SARS-CoV2 infection.

Commentary: The Long History of Vitamin C: From Prevention of the Common Cold to Potential Aid in the Treatment of COVID-19

“…Our meta-analysis on vitamin C and the common cold found that vitamin C did not decrease the average number of colds in general community trials ( 2 ). However, we found that in five trials with 598 physically active participants vitamin C decreased common cold risk by 52% (P < 0.00001) ( 2 ), yet this effect was not mentioned by Cerullo ( 1 ). Furthermore, in one of the largest trials to date, Anderson (1972) ( 5 ) found that the occurrence of outcomes “not confined to the house” , “not off work” , and “not ill during the trial” because of common cold related symptoms were all about 8 percentage points lower in the vitamin C group than in the placebo group ( Table 1 ).…”

“…A review of the effects of vitamin C on the immune system and respiratory tract infections was recently published ( 1 ). We are the authors of a review of vitamin C and the common cold ( 2 ), which was cited in the article.…”

Dietary and Protective Factors to Halt or Mitigate Progression of Autoimmunity, COVID-19 and Its Associated Metabolic Diseases

“…Moreover, quercetin and vitamin C could be combined to yield a synergistic effect against COVID-19 [ 60 ]. The use of vitamin C as a preventive supplement against COVID-19 has a strong rationale, as we previously reported [ 65 ].…”

Current Updates on Naturally Occurring Compounds Recognizing SARS-CoV-2 Druggable Targets

“…It has tablished antioxidant properties by scavenging oxygen free radicals and represen cofactor for the production of several neurotransmitters and hormones. Vitamin C supports several cellular functions of both innate and adaptive systems [37,38]. Furthermore, upcoming studies demonstrated its anti-inflam properties, being able to inhibit pro-inflammatory mediators production, includ TNF-α, and the granulocyte-macrophage colony-stimulating factor (GM-CSF) si responses [39].…”

“…Other outcom considered in the same clinical trial, including organ failure score, intensive c length, and mortality. According to the authors, a significant decrease in intens unit stay and hospital mortality was observed in the vitamin C treated patie Vitamin C supports several cellular functions of both innate and adaptive immune systems [37,38]. Furthermore, upcoming studies demonstrated its anti-inflammatory properties, being able to inhibit pro-inflammatory mediators production, including IL-6, TNF-α, and the granulocyte-macrophage colony-stimulating factor (GM-CSF) signalling responses [39].…”