- Review of the protective effects of a few dietary supplements against COVID-19.
Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV 2) is a viral pathogen of the Coronaviradae family of viruses that causes coronavirus disease (COVID-19). The world is currently in the middle of a global COVID-19 pandemic that has had far reaching implications on all aspects of life. The World Health Organisation recommends a myriad of best practices intended to protect one from getting a COVID-19 infection, the most prominent of which involves good personal hygiene and social distancing. In addition they make recommendations to practice healthy eating habits such as eating whole unprocessed grains, fruits and vegetables whilst limiting intake of excessive fats, salt, sugar and alcohol(World Health Organization (WHO), 2020). Nutrition is thought to play an important role in the prognosis of COVID-19. In this regard special attention has been given to certain dietary elements and their possible therapeutic benefits.
- Vitamin-D
There are two primary mechanisms by which vitamin-D is thought to be metabolized in the human body. Through the skin Vitamin D synthesis takes place when UVB reaches 7-dehydrocholesterol within the skin, the subsequent thermal reaction results in the production of vitamin D3. Vitamin D consumed orally is converted to 25-hydroxyvitamin-D (calcitriol), it’s biologically active form, in the liver. Vitamin D has a variety of mechanisms of activating the immune system to minimise infection and death. One of these mechanisms is triggering cell innate immunity by induction of antimicrobial peptides and defensins(Grant et al., 2020).
Administration of vitamin D has been demonstrated to have an immune-modulatory effect by reducing the production of pro-inflammatory cytokines that are produced in response to viral infections. This is achieved by the suppression of T helper cell type 1(Th1) responses by the vitamin D metabolite calcitriol. In addition calcitriol stimulates T helper type 2 cells resulting in the production of cytokines that indirectly suppress Th1 cells. Calcitriol has the effect of inducing T regulatory cells, overall reducing inflammation(Grant et al., 2020; Iddir et al., 2020).
- Vitamin-C(Ascorbic acid)
Vitamin C is an antioxidant that has a protective effect against oxidative stress that results from free radicals such as Reactive Oxygen Species(ROS). Supplementation of vitamin C is known to shorten the duration of lower respiratory tract infections such as the common cold, however it does not reduce the risk of contracting a common cold infection(Carr, 2019). In-vitro studies on bird organ cultures showed that vitamin C increased the cells resistance to coronavirus infection. Control trials involving humans have shown that supplementation of vitamin C reduces the incidence of pneumonia. It could be inferred that vitamin C might reduce one’s susceptibility to lower respiratory tract infection like COVID-19(Zhang & Liu, 2020).
There remains at the moment no proven prophylactic treatment for COVID-19, best practices to prevent infection such as social distancing and hand-washing are still the best tools available to societies if they wish to survive this pandemic. Proper nutrition is a key component in the maintenance of a robust immune system and could play an essential role in improving the outcomes of those infected with COVID-19.
Carr, A. C. (2019). Vitamin C administration in the critically ill: A summary of recent meta-analyses. Critical Care, 23(1), 1–3. https://doi.org/10.1186/s13054-019-2538-y
Grant, W. B., Lahore, H., McDonnell, S. L., Baggerly, C. A., French, C. B., Aliano, J. L., & Bhattoa, H. P. (2020). Evidence that vitamin d supplementation could reduce risk of influenza and covid-19 infections and deaths. Nutrients, 12(4), 1–19. https://doi.org/10.3390/nu12040988
Iddir, M., Brito, A., Dingeo, G., Del Campo, S. S. F., Samouda, H., La Frano, M. R., & Bohn, T. (2020). Strengthening the immune system and reducing inflammation and oxidative stress through diet and nutrition: Considerations during the covid-19 crisis. Nutrients, 12(6), 1–39. https://doi.org/10.3390/nu12061562
World Health Organization (WHO). (2020). #HealthyAtHome: Healthy Diet. Retrieved from https://www.who.int/campaigns/connecting-the-world-to-combat-coronavirus/healthyathome/healthyathome—healthy-diet
Zhang, L., & Liu, Y. (2020). Potential interventions for novel coronavirus in China: A systematic review. Journal of Medical Virology, 92(5), 479–490. https://doi.org/10.1002/jmv.25707