Nutrition During COVID-19

Nutrition During COVID-19

Among the well-known public health practices like handwashing and reducing contact with other people, in this article we are going to look at a couple of key nutrients that can help make sure that you are doing your best to support your immune system.


This article is a guest post from our dietitian friend Aleksandra Jagiello, BSc, MSc, RD.


Although the first wave appears to have flattened, COVID-19 is unfortunately not going to disappear soon. Among the well-known public health practices like handwashing and reducing contact with other people, in this article we are going to look at a couple of key nutrients that can help make sure that you are doing your best to support your immune system and increase resistance to infections.

It’s well documented that good quality nutrition plays an important role in maintaining a healthy immune system. Poor nutrition leads to a higher risk of viral or bacterial infections. At the same time, chronic health conditions and infections often contribute to a weak nutritional status of affected individuals.

As indicated throughout the onset of the COVID-19 pandemic, those affected the most severely by the infection are older people and individuals with chronic diseases such as hypertension, cancer or diabetes. Hence, it’s particularly important to address and promote the preventative role of nutrition within this population.

At present, there is not enough research to draw conclusions concerning nutritional components in relation to risk and severity of COVID-19, but it’s certainly worth considering available data indicating the role of certain nutrients in preventing and/or countering infections.


Can you actually ‘boost’ your immune system?

It’s important to note that during infection, there is a vast increase in metabolic activity of the immune system due to the body burning more energy, producing new cells and making new proteins such as antibodies to combat the pathogens. Individuals going through an infection therefore require additional energy and micronutrients (vitamins & minerals) to support the immune system.

There is strong scientific evidence regarding the roles of Vitamin D, Vitamins C & Zinc in immune system function.




The role of Vitamin D and its RNI (Reference Nutrient Intake) has been previously described here.

It’s been recently discussed that Vitamin D supplementation may play a preventative and therapeutic role during the COVID-19 pandemic1.

A recent study suggested that Vitamin D deficiency can contribute to a severe onset of COVID-19. This could be especially true within an elderly population whose innate immune system response might be weaker and result in an increased viral load2. An overly activated adaptive immune system in response to the infection leads to an increased production of cytokines and a cytokine storm3 (a process where the body starts to attack its own cells & tissues instead of just fighting off the infection), which in some cases might become fatal as has been observed in patients with COVID-19. Vitamin D has been found to enhance the innate immune system but also to partially prevent the induction of cytokine storm by reducing the production of pro-inflammatory cytokines4.

Supplementation with Vitamin D also has been reported to increase the expression of genes related to antioxidation and enhanced glutathione production5. Glutathione, in turn, helps to avoid unnecessary waste of Vitamin C which was proposed for the prevention and the treatment of COVID-196.

It’s also worth mentioning that serum vitamin D concentrations tend to decrease with age due to several reasons such as taking certain types of drugs (i.e. antibiotics, anti-epileptics, anti-inflammatory agents) or less time spent in the sun.

***The UK government is recommending to everyone living in the UK, to supplement with 10 mcg of Vitamin D through the winter months and to people in risk groups to supplement with Vitamin D throughout the whole year. More about Vitamin D can be found here.




Vitamin C (ascorbic acid) is a water-soluble vitamin known for its antioxidant & antiviral effects7. Although severe deficiency of vitamin C occurs rarely, it’s important to note that the human body is unable to synthesize it, therefore it needs to be provided by the daily diet. 

Since there isn’t an effective antiviral drug or a suitable vaccine for COVID-19 yet, the alternative treatments are being proposed. One of the approaches include high-dose of intravenous Vitamin C (IV Vit-C) which has been utilized in China in the treatment of COVID-19 and showed promising results8. The most significant effect of IV Vit-C was that of reducing the cytokine storm among hospitalized patients and strengthening the body’s immune response.

Clearly, more research is needed to establish and review the relevance of using Vitamin C pre-infection, during the onset of the COVID-19 (throughout different stages of the disease) as well as post-infection. Nonetheless, it’s justified to consume at least 40mg of Vitamin C daily (for adults) as recommended by Scientific Advisory Committee on Nutrition (SACN)9. The minimum intake of Vitamin C can be satisfied with as little as one orange a day, however, it’s beneficial to eat more than this amount from a variety of fruits and vegetables to increase Vitamin C intake.




Zinc is a nutritionally fundamental trace element and it has been known as a regulator of inflammatory response and for its antiviral and antibacterial properties. Even though there is no evidence from clinical trials as of now, it is believed that Zinc may exert beneficial effects on COVID-19 infections. Data from in vitro research shows that Zn2+ demonstrates antiviral activity via inhibition of SARS-CoV RNA polymerase10. Another protective mechanism of Zn2+ is the decreasing of the activity of the SARS-CoV-2 receptor10. It has been also demonstrated that both Zinc deficiency11 and its excess in the human body12, led to negative outcomes in the regulation of cell production in the immune system13.

Although Zinc might not play a relevant role in the treatment of COVID-9, its protective effects should not be underestimated. Providing enough Zinc from the diet or through supplementation when necessary can have a preventive role against infectious diseases by supporting immune function14 and/or reducing inflammation13.

The recommended daily intake of Zinc depends on various factors such as weight, sex, age. In adults (aged 19-50) the RNI is 7mg/day for healthy females and 9.5mg/day for healthy males. Good sources of this essential mineral include red meat, legumes, nuts (especially cashews) and fortified breakfast cereals.

Over the years it’s been shown that vegans are vegetarians are at risk for zinc deficiency and should pay close attention to their zinc intake and supplement if necessary.




COVID-19 is likely going to linger for a while. It is therefore more important than ever to pay attention to our diet. Both to protect ourselves from the virus and to help support our immune system if the infection does occur.

While this article focused on Vitamins D & C along with zinc, it’s still crucial to provide an adequate intake of other nutrients such as iron, and vitamins A, E, B6, and B12, and omega-3 fatty acids which also contribute to the functioning of immune system15.

Moreover, it’s also worth noting that a healthy diet in general consists of fruits, vegetables, legumes, whole grains, moderate consumption of dairy foods, fish, nuts and a limited consumption of refined carbohydrates, sugars and processed meat. A diet consisting of these foods is likely to provide the necessary nutrients for a healthy immune system. If you are excluding certain food groups (like animal products) or struggling to eat your 5-a-day, it could be a good idea to supplement your dietary intake with a daily multivitamin. This way you can be sure that you are providing your body with the appropriate amount of nutrients needed to maintain a healthy immune system and ensure that the sufficient amount of immune cells and antibodies is produced to tackle any infection including COVID-19.



  1. Grant, W.B.; Lahore, H.; McDonnell, S.L.; Baggerly, C.A.; French, C.B.; Aliano, J.L.; Bhattoa, H.P. Evidence that Vitamin D Supplementation Could Reduce Risk of Influenza and COVID-19 Infections and Deaths. Nutrients 2020, 12, 988
  2. The Possible Role of Vitamin D in Suppressing Cytokine Storm and Associated Mortality in COVID-19 Patients. Ali Daneshkhah, Vasundhara Agrawal, Adam Eshein, Hariharan Subramanian, Hemant Kumar Roy, Vadim Backman; doi:
  3. Qin, L. Zhou, Z. Hu, S. Zhang, S. Yang, Y. Tao, C. Xie, K. Ma, K. Shang, W. Wang, D.-S. Tian, Dysregulation of Immune Response in Patients with COVID-19 in Wuhan, China, Social Science Research Network, Rochester, NY, 2020.
  4. Lemire, J.M.; Adams, J.S.; Kermani-Arab, V.; Bakke, A.C.; Sakai, R.; Jordan, S.C. 1,25-Dihydroxyvitamin D3 suppresses human T helper/inducer lymphocyte activity in vitro. J. Immunol. 1985, 134, 3032–3035.
  5. Lei, G.S.; Zhang, C.; Cheng, B.H.; Lee, C.H. Mechanisms of Action of Vitamin D as Supplemental Therapy for Pneumocystis Pneumonia. Antimicrob. Agents Chemother. 2017, 61.
  6. Wimalawansa, S.J. Global epidemic of coronavirus–COVID-19: What we can do to minimze risksl. Eur. J. Biomed. Pharm. Sci. 2020, 7, 432–438
  7. Colunga Biancatelli R.M.L., Berrill M., Marik P.E. The antiviral properties of vitamin C. Expert Rev. Anti. Ther. 2020;18(2):99–101
  8. Intravenous vitamin C for reduction of cytokines storm in acute respiratory distress syndrome; Alberto Banik Boretti* and Bimal Krishna. doi: 10.1016/j.phanu.2020.100190
  10. Zinc and respiratory tract infections: Perspectives for COVID-19 (review).
  11. T-lymphocytes: a target for stimulatory and inhibitory effects of zinc ions. Hönscheid A, Rink L, Haase H. Endocr Metab Immune Disord Drug Targets. 2009 Jun; 9(2):132-44.
  12. Zinc inhibits interleukin-1-dependent T cell stimulation. Wellinghausen N, Martin M, Rink LEur J Immunol. 1997 Oct; 27(10):2529-35.
  13. Zinc in Infection and Inflammation. Nour Zahi Gammoh and Lothar Rink. doi: 10.3390/nu9060624
  14. Zinc and the risk for infectious disease. Fischer Walker C1, Black RE. DOI: 10.1146/annurev.nutr.23.011702.073054
  15. Exercise, nutrition and immune function Michael Gleeson,David C Nieman &Bente K Pedersen Pages 115-125 | Accepted 07 Aug 2003, Published online: 18 Feb 2007.


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