Can Vitamin C Prevent COVID-19?

The outbreak of COVID-19 has created a global public health crisis. Our knowledge continues to be limited about the protective factors of this infection. Therefore, preventive health measures that can reduce the risk of infection, and halt the progression and severity of symptoms and complications related to COVID-19 are desperately needed. In the midst of the COVID-19 pandemic, health promotion measures, such as proper nutrition, physical activity, rest, and stress reduction measures have been advocated.  More recently, attention has been shifted to vitamin supplementation as a means to keep American’s health and immune system in optimal status.

Adequate intake of micronutrients is critical for optimal health, growth and development, and healthy aging. However,  the Dietary Guidelines for Americans 2015–2020 highlight low-consumption of important nutrients including vitamins A, C, D and E, calcium, magnesium, iron, potassium, choline and fiber, with variations by age groups.¹   Vitamin C has recently gained attention as a potential micronutrient in the prevention of COVID-19.  Vitamin C has been known for promoting the oxidant scavenging activity of the skin, potentially protecting against environmental oxidative stress, enhancing chemotaxis, phagocytosis, and microbial killing.²

Based on previous evidence, oral vitamin C (2-8 g/day) may reduce the incidence and duration of respiratory infections and intravenous vitamin C (6-24 g/day) has been shown to reduce mortality, hospital length of stay, and time on mechanical ventilation for severe respiratory infections^3-4

Given the favorable safety profile and low cost of vitamin C, and the frequency of vitamin C deficiency in respiratory infections, trials are currently underway to determine its effect in hospitalized patients with COVID-19.^4-5  Although there are currently no published results of these clinical trials due to the novelty of SARS-CoV-2 infection, there is pathophysiologic rationale for exploring the use of vitamins such as Vitamin C in this global pandemic.⁶

While we await for results from these trials, we need to continue being vigilant, and adhere to a varied and balanced diet with an abundance of fruits and vegetables and the essential nutrients known to contribute to the normal immune system functioning.  Vitamin C supplementation could present a safe and inexpensive approach to prevention of respiratory diseases, and perhaps aid in COVID-19.⁷

Avoidance of deficiencies and identification of suboptimal intakes of these micronutrients in targeted groups of patients and in distinct and highly sensitive populations could help to strengthen the resilience of people to the COVID-19 pandemic. It will be also important to highlight evidence-based public health messages, to prevent false and misleading claims about the benefits of vitamin supplements. It will also be important to communicate the exploratory state of research on micronutrients and COVID-19 infection and that no diet will prevent or cure COVID-19 infection. Frequent handwashing and social distancing will continue to be critical to reduce transmission during this pandemic.⁸

 

References:

1. Blumberg JB, Frei B, Fulgoni VL, Weaver CM, Zeisel SH. Contribution of Dietary Supplements to Nutritional Adequacy in Various Adult Age Groups. Nutrients. 2017;9(12):1325. Published 2017 Dec 6. doi:10.3390/nu9121325
2. U.S. Department of Health and Human Services. U.S. Department of Agriculture [(accessed on 15 March 2017)];2015–2020 Dietary Guidelines for Americans. (8th ed.). 2015 Available online: http://health.gov/dietaryguidelines/2015/guidelines/
3. Holford P, Carr AC, Jovic TH, et al. Vitamin C-An Adjunctive Therapy for Respiratory Infection, Sepsis and COVID-19. Nutrients. 2020;12(12):3760. Published 2020 Dec 7. doi:10.3390/nu12123760
4. Carr AC. A new clinical trial to test high-dose vitamin C in patients with COVID-19. Crit Care. 2020;24(1):133. Published 2020 Apr 7. doi:10.1186/s13054-020-02851-4
5. Zhang J, Rao X, Li Y, et al. Pilot trial of high-dose vitamin C in critically ill COVID-19 patients. Ann Intensive Care. 2021;11(1):5. Published 2021 Jan 9. doi:10.1186/s13613-020-00792-3
6. Jovic TH, Ali SR, Ibrahim N, et al. Could Vitamins Help in the Fight Against COVID-19?. Nutrients. 2020;12(9):2550. Published 2020 Aug 23. doi:10.3390/nu12092550
7. Allegra A, Tonacci A, Pioggia G, Musolino C, Gangemi S. Vitamin deficiency as risk factor for SARS-CoV-2 infection: correlation with susceptibility and prognosis. Eur Rev Med Pharmacol Sci. 2020;24(18):9721-9738. doi:10.26355/eurrev_202009_23064
8. Richardson DP, Lovegrove JA. Nutritional status of micronutrients as a possible and modifiable risk factor for COVID-19: a UK perspective [published online ahead of print, 2020 Aug 20]. Br J Nutr. 2020;1-7. doi:10.1017/S000711452000330X

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