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

Front Immunol. 2020 Oct 28;11:574029. doi: 10.3389/fimmu.2020.574029. eCollection 2020.

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 well-nourished 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.

Keywords: COVID-19; athletes; frail elderly subjects; immune function; non-communicable diseases; pneumonia; viral infections; vitamin C supplementation.

Publication types

  • Review

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Ascorbic Acid / adverse effects
  • Ascorbic Acid / immunology*
  • Ascorbic Acid / therapeutic use*
  • COVID-19 / drug therapy*
  • COVID-19 / virology
  • Child
  • Child, Preschool
  • Common Cold / drug therapy*
  • Common Cold / prevention & control*
  • Critical Illness
  • Dietary Supplements
  • Female
  • Humans
  • Infant
  • Male
  • Middle Aged
  • SARS-CoV-2*
  • Vitamins / therapeutic use*
  • Young Adult

Substances

  • Vitamins
  • Ascorbic Acid

Supplementary concepts

  • COVID-19 drug treatment