Introduction

The SARS-CoV-2 coronavirus is wreaking havoc on the world with such a powerful force that no country is spared from its infections. Begins in December 2019, the disease caused by this novel coronavirus, known as COVID-19, already claimed over 120,000 lives with close to 2 million confirmed cases as of April 15, 2020 [1]. The disease is highly infectious and can silently transmit to others from a human carrier who has no symptoms at all [2]. Many countries have implemented isolation and social distancing measures to slow its spread, resulting in much of the world living in lockdown.

There is currently no effective treatment for this novel coronavirus. Although the research and development of a vaccine with as many as 115 potential candidates are now underway, the earliest that any vaccine can be available is not until early 2021. In the meantime, many doctors and scientists are actively trying to repurpose existing drugs and treatment methods to treat the COVID-19 with varying results. Among them include anti-viral agents used to treat SARS (Lopinavir-ritonavir), an experimental drug for Ebola virus (Remdesivir), and old anti-malarial mediations (Chloroquine / Hydroxychloroquine). Many clinical trials are currently in progress to validate the effectiveness of the treatment. The hunt for a cure is on-going.

Common Symptoms of COVID-19

Nutrition is Essentials

The use of nutritional intervention as a support to prevent and control the disease has been suggested. During viral infections, a deficit in any specific vitamin and micronutrient can be harmful. A rapid advice guideline issued to the frontline doctors in China suggested COVID-19 patients should eat protein-rich foods and carbohydrate-containing diets to maintain physical strength. Nutritional supplements should be given to patients who are at risk of malnutrition as early as possible [3]. Many micronutrients, including vitamin A, B group, C, D, E, omega-3 polyunsaturated fatty acids, selenium, zinc, and iron, can be potentially effective for the general treatment of viral infections [4]. Hence, doctors in Italy have resorted to injecting multivitamin solutions to all hospitalised COVID-19 patients to prevent against any deficiency [5].

More notably, supplementation of vitamin D, C, and pre- or probiotics is especially useful to reduce the risk of COVID-19, based on the currently reported treatment experience,

Vitamin D

Physiologically, vitamin D can lower the replication rate of viruses by strengthening the cell-to-cell junctions [6]. Vitamin D can also improve cellular immunity through induction of antimicrobial peptides to destroy invading microbes such as bacteria and viruses. Additionally, Vitamin D can reduce the production of pro-inflammatory cytokines and increases the expression of anti-inflammatory cytokines, which help to reduce inflammation [6]. People at risk of COVID-19 should consider taking 10,000 IU/d, followed by 5000 IU/d, of vitamin D3 for a few weeks to raise the level of 25-hydroxyvitamin D [25(OH)D] in the blood rapidly. The goal should be to increase the 25(OH)D status above 40–60 ng/mL (100–150 nmol/L) [6].

Vitamin C

Vitamin C is also a potentially useful supplement for COVID-19 infection due to its antioxidant activity, which may reduce oxidative stress and inflammation as well as enhance the immune system. Supplementing vitamin C has also been shown to reduce the risk of severity of influenza [7]. In patients with pneumonia, there is a potential risk of developing sepsis, an out-of-balance bodily response to infections that can damage multiple organs. Sepsis can progress to sepsis shock where the blood pressure drops dramatically leading to death. Vitamin C can constrict the blood vessel to elevate blood pressure and thus saving lives. A clinical trial is currently underway to investigate the use of intravenous infusion of vitamin C for severe COVID-19 infected pneumonia [7].        

Pre- and Probiotics

Pre- and probiotics are also emerging as useful supplements for COVID-19 infection. Some patients with COVID-19 showed an imbalance in the intestinal microbial (dysbiosis), with decreased probiotics such as Lactobacillus and Bifidobacterium [8]. Not a surprising finding since patients with respiratory infections generally have gut dysfunction, even though the respiratory tract has a distinct microbial ecology from the gut. The is a link between the lung and the gastrointestinal tract, although it is still poorly understood [9]. However, both the lungs and the intestines have a high concentration of angiotensin-converting enzyme 2 (ACE2), a type of enzyme attached to the cell membrane. The SARS-CoV-2 coronavirus appears to attack the cell by binding to the ACE2 [10]. Therefore, both lungs and intestines are targets for SARS-CoV-2 assaults. Improving the gut microbiota has been suggested as a possible means to reduce inflammation at the lungs via the gut-lung crosstalk [11]. Doctors in China applied prebiotics and probiotics to regulate the balance of intestinal microbiota and reduce the risk of any secondary infection [8].

The functions of probiotics at a glance.

Conclusion

Nutritional supplements can play a crucial supporting role in preventing and treating COVID-19. Vitamin D, vitamin C, as well as pre- and probiotics are known examples that have been used in practice to support COVID-19 treatment. They are generally safe and widely available, hence, can be used by the general public as a preventive measure in addition to practising social distancing and good personal hygiene. For COVID-19 patients with mild symptoms, taking vitamin D, vitamin C, and pre- or probiotics immediately is highly recommended to prevent any deterioration of the condition.

References

[1]        World Health Organisation, Coronavirus disease 2019, (n.d.). https://www.who.int/emergencies/diseases/novel-coronavirus-2019 (accessed April 15, 2020).

[2]        Y. Bai, L. Yao, T. Wei, F. Tian, D.-Y. Jin, L. Chen, M. Wang, Presumed Asymptomatic Carrier Transmission of COVID-19, JAMA. 323 (2020) 1406–1407. doi:10.1001/jama.2020.2565.

[3]        Y.-H. Jin, L. Cai, Z.-S. Cheng, H. Cheng, T. Deng, Y.-P. Fan, C. Fang, D. Huang, L.-Q. Huang, Q. Huang, Y. Han, B. Hu, F. Hu, B.-H. Li, Y.-R. Li, K. Liang, L.-K. Lin, L.-S. Luo, J. Ma, L.-L. Ma, Z.-Y. Peng, Y.-B. Pan, Z.-Y. Pan, X.-Q. Ren, H.-M. Sun, Y. Wang, Y.-Y. Wang, H. Weng, C.-J. Wei, D.-F. Wu, J. Xia, Y. Xiong, H.-B. Xu, X.-M. Yao, Y.-F. Yuan, T.-S. Ye, X.-C. Zhang, Y.-W. Zhang, Y.-G. Zhang, H.-M. Zhang, Y. Zhao, M.-J. Zhao, H. Zi, X.-T. Zeng, Y.-Y. Wang, X.-H. Wang,  for the ZH of WUNCM and R.T. Evidence-Based Medicine Chapter of China International Exchange and Promotive Association for Medical and Health Care (CPAM), A rapid advice guideline for the diagnosis and treatment of 2019 novel coronavirus (2019-nCoV) infected pneumonia (standard version), Mil. Med. Res. 7 (2020) 4. doi:10.1186/s40779-020-0233-6.

[4]        L. Zhang, Y. Liu, Potential interventions for novel coronavirus in China: A systematic review, J. Med. Virol. 92 (2020) 479–490. doi:10.1002/jmv.25707.

[5]        R. Caccialanza, A. Laviano, F. Lobascio, E. Montagna, R. Bruno, S. Ludovisi, A.G. Corsico, A. Di Sabatino, M. Belliato, M. Calvi, I. Iacona, G. Grugnetti, E. Bonadeo, A. Muzzi, E. Cereda, Early nutritional supplementation in non-critically ill patients hospitalised for the 2019 novel coronavirus disease (COVID-19): Rationale and feasibility of a shared pragmatic protocol, Nutrition. (2020) 110835. doi:https://doi.org/10.1016/j.nut.2020.110835.

[6]        W.B. Grant, H. Lahore, S.L. McDonnell, C.A. Baggerly, C.B. French, J.L. Aliano, H.P. Bhattoa, Evidence that Vitamin D Supplementation Could Reduce Risk of Influenza and COVID-19 Infections and Deaths, Nutrients. 12 (2020) 988. doi:10.3390/nu12040988.

[7]        S.G.V. Rosa, W.C. Santos, Clinical trials on drug repositioning for COVID-19 treatment, Rev. Panam. Salud Publica. 44 (2020) e40–e40. doi:10.26633/RPSP.2020.40.

[8]        K. Xu, H. Cai, Y. Shen, Q. Ni, Y. Chen, S. Hu, J. Li, H. Wang, L. Yu, H. Huang, Y. Qiu, G. Wei, Q. Fang, J. Zhou, J. Sheng, T. Liang, L. Li, Management of corona virus disease-19 (COVID-19): the Zhejiang experience, Zhejiang Da Xue Xue Bao. Yi Xue Ban. 49 (2020) 0.

[9] QY. Gao, Y.X. Chen, J.Y. Fang, 2019 Novel coronavirus infection and gastrointestinal tract, J. Dig. Dis. 21 (2020) 125–126. doi:10.1111/1751-2980.12851.

[10]      H. Zhang, J.M. Penninger, Y. Li, N. Zhong, A.S. Slutsky, Angiotensin-converting enzyme 2 (ACE2) as a SARS-CoV-2 receptor: molecular mechanisms and potential therapeutic target, Intensive Care Med. 46 (2020) 586–590. doi:10.1007/s00134-020-05985-9.

[11]      R. Enaud, R. Prevel, E. Ciarlo, F. Beaufils, G. Wieërs, B. Guery, L. Delhaes, The Gut-Lung Axis in Health and Respiratory Diseases: A Place for Inter-Organ and Inter-Kingdom Crosstalks, Front. Cell. Infect. Microbiol. 10 (2020) 9. doi:10.3389/fcimb.2020.00009.

[12]      I. Thevarajan, K.L. Buising, B.C. Cowie, Clinical presentation and management of COVID-19, Med. J. Aust. (2020). https://www.mja.com.au/journal/2020/clinical-presentation-and-management-covid-19 (accessed April 15, 2020).

[13]      P. Kakodkar, N. Kaka, M.N. Baig, A Comprehensive Literature Review on the Clinical Presentation, and Management of the Pandemic Coronavirus Disease 2019 (COVID-19), Cureus. 12 (2020) e7560. doi:10.7759/cureus.7560.

[14]      R.E. Jordan, P. Adab, K.K. Cheng, Covid-19: risk factors for severe disease and death, BMJ. 368 (2020) m1198. doi:10.1136/bmj.m1198.