Since the COVID-19 pandemic started there have been multiple messages on social media to use Vitamin C to prevent Coronavirus infection. In this article, we will review the published research studies regarding vitamin C and if it can truly prevent Coronavirus infection. Most of the studies published so far looked at vitamin C effect on common cold and other viral infections. As COVID-19 pandemic recently started, there are no published articles regarding Vitamin C effect on Novel Coronavirus infection. We may have to extrapolate the results of the previous studies to this current pandemic.
Vitamin C was first isolated in 1930s and it has been proposed for treating respiratory infections since then. Apparently, it became popular when Nobel laureate Linus Pauling recommended vitamin C to prevent and alleviate the common cold. Ritzel’s study in 1961 was the first largest randomized trial that demonstrated a significant reduction in the incidence and duration of common colds in children who were administered vitamin C. There were multiple studies since then including Anderson study, Dykes study and Chalmers study in 1975 that did not have similar results.
Four trials in UK found a moderate reduction in common cold incidence with vitamin C which was explained particularly by low dietary vitamin C rather than high doses of supplements. Three trials that included participants under heavy physical stress like marathon and skiing found a reduction in the incidence of common colds with vitamin C. There are dozens of other studies that showed heterogenous results with few studies showing mild to moderate reduction in common colds and few studies unable to demonstrate any benefits.
Vitamin C is an efficient antioxidant and it can boost immunity by reducing oxidative stress caused by viral and bacterial infections. It is proven to have reduction in the severity of illness in multiple animal studies, however, studies in human beings did not produce similar results. In one study, even intravenous Vitamin C infusion did not significantly improve organ dysfunction or reduced markers of inflammation in patients with sepsis.
In conclusion, considering all the studies, regular administration of vitamin C may not really have any significant benefit to reduce the incidence of common cold in general population. In special circumstances, where people are engaged in extreme physical exertion or exposed to stress may have a beneficial effect of regular supplementation. It also has few benefits in children. Given the ambiguity of the research studies and lack of any adverse effects of vitamin C, it may be used as a supplement on an individual basis to prevent common cold or Coronavirus infection, however, it is important to remember that there is no strong evidence to prove it.
Effect of Vitamin C Infusion on Organ Failure and Biomarkers of Inflammation and Vascular Injury in Patients With Sepsis and Severe Acute Respiratory Failure: The CITRIS-ALI Randomized Clinical Trial. Fowler AA et al. JAMA. 2019 Oct 1;322(13):1261-1270. doi: 10.1001/jama.2019.11825.
What are the effects of vitamin C on the duration and severity of the common cold? Quidel S et al. Medwave. 2018 Oct 3;18(6):e7261. doi: 10.5867/medwave.2018.06.7260.
Does vitamin C prevent the common cold? Gomez E et al. Medwave. 2018 Aug 6;18(4):e7235. doi: 10.5867/medwave.2018.04.7236.
Critical care management of adults with community-acquired severe respiratory viral infection. Arabi YM et al. Intensive Care Med. 2020 Feb;46(2):315-328. doi: 10.1007/s00134-020-05943-5