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At this point, with COVID-19 cases on the increase again and the UK on the verge of a second lockdown, everyone wants to know what can be done to get our lives back to normal. While, unfortunately, no cure has been developed yet, research has come to light about the effects of vitamin D in reducing COVID-19 symptoms and possibly reducing the risk of catching it. Here, Holly Roberts, who recently graduated from University College Birmingham, takes over the NHD Blog spot to investigate the facts surrounding vitamin D and its impact on COVID-19.

Vitamin D deficiency is a worldwide public health problem; it is estimated up to 1 billion people worldwide suffer with insufficient vitamin D intake, both in developed and developing countries. In the UK, government figures show around 14.5% of adults are vitamin D deficient, with this percentage increasing to 30% in those over 65 years old.1


Vitamin D is a fat-soluble vitamin, which plays an important role in many bodily functions, such as the absorption of calcium, which, as we all know, is vital in maintaining healthy bones and teeth.It’s also needed for cell growth and the proper functioning of nerves and muscles.

In addition, vitamin D helps strengthen our immune system (the body’s first line of defence against viruses and bacteria), by enhancing the function of T-cells and macrophages (cells that help protect your body against viruses and bacteria) and thereby reducing inflammation. Research has shown inflammation can induce tissue and organ damage, which healthcare professionals have now said can be a side effect for up to seven months after being infected with COVID-19.3

Vitamin D reduces the risk of respiratory tract infections through three mechanisms: maintaining tight cell junctions, killing the virus through anti-microbial proteins, and reducing the production of proinflammatory cytokines. This is important, as COVID-19 (other than the virus virulence) is caused mostly because of these proinflammatory cytokines.3


As a fundamental part of the immune system, cytokines are a group of proteins released by cells to control the functioning of other cells. They act as intracellular chemical messengers, which effect changes in cell behaviour, and play an important role in cell reproduction, growth and development, helping to protect the body against infections. Cytokines can have both proinflammatory and anti-inflammatory effects, and have been known to induce tissue damage, as well as enhance disease progression and severity.4


A study conducted on NHS staff at University Hospitals Birmingham NHS Foundation Trust, analysed blood samples from 392 healthcare workers. They were tested for COVID antibodies and vitamin D concentrations. Out of the 392 participants involved, 55% showed the virus antibodies, which meant they had been infected, and out of those, 15.6% were deficient in vitamin D. Results showed that staff who were vitamin D deficient were more likely to report symptoms of body aches and pains, but not respiratory symptoms including breathlessness or a continuous cough. Vitamin levels were also lower in staff who reported symptoms of fever. As a whole, there was an increase in the development of detectable antibodies in participants with vitamin D deficiency.5


From the research coming to light and the winter approaching, it’s becoming clear that we need to pay attention to our vitamin D levels. The NHS is recommending people should take a supplement of 10 micrograms of vitamin D per day (the daily recommended amount) in order to supply enough of the vitamin to the body for it to play a role in all necessary functions, such as strengthening the immune system and potentially decreasing the risks associated with the corona virus.6


So, what are the sources of vitamin D?

Food sources include:

  • mushrooms
  • oily fish such as salmon, mackerel, herring and sardines
  • eggs
  • red meat and liver
  • fortified foods such as dairy and cereals

However, getting enough vitamin D from the diet alone is difficult, as foods do not contain enough to satisfy our body’s needs, which is where the sun comes in. Our bodies create vitamin D when exposed to UV radiation. However, many factors can affect the amount of the vitamin our bodies is able to make. Firstly, the amount of time spent in the sun, as well as the use of sun protections such as creams and clothing, and the amount of melanin (pigment) in a person’s skin also can affect the amount your body is able to make (the more melanin present in the skin the less vitamin D your body is able to produce).


It is important to keep in mind that although evidence suggests vitamin D has a positive impact on reducing the risk and symptoms associated with coronavirus, this is all still new, and no information has been proven yet (otherwise we would have a cure). Research also suggests that vitamin D may help the immune system ward off harmful viruses and bacteria. Nevertheless, there is still a high percentage of people lacking in vitamin D, so taking a daily supplement has to be recommended, at the very least it promotes bone health, lowering the risk of developing illnesses such as arthritis and osteoporosis.


The evidence coming out of ongoing data reveals that COVID-19 can cause long-term bodily damage, as well as debilitating symptoms for many months after recovery. It is not only important to help prevent the spread of the virus, but we must do all we can to keep ourselves fit and well. Making sure we are consuming enough vitamin D to get our immune system as strong as possible will help us to fight off the virus.1

If you have enjoyed this article, and would like to get in touch with me, my email address is [email protected] 

Holly Roberts BSc (Hons) 

Since she was 11 years old, Holly has loved nutrition
and knew it was what she wanted to do as a career.
Holly graduated from the University College
Birmingham last year with a 2:1.


  1. GP Notebook (2019). Vitamin D deficiency.Available at: https://gpnotebook.com/simplepage.cfm?ID=-200933361#:~:text=Vitamin%20D%20deficiency%20is%20common%20in%20northern%20Europe.,as%2094%25%20in%20otherwise%20healthy%20south%20Asian%20adults, accessed: 12th October 2020
  2. Sizar O, Khare S, Goyal A, Bansal P and Givler A (2020). Vitamin D Deficiency. Statpearls,1 (1), 1
  3. Grant WB, Lahore H, McDonnell SL, Baggerly CA, French CB, Aliano JL, Bhattoa HP (2020). Evidence that vitamin D supplementation could reduce risk of influenza and COVID-19 infections and deaths. Nutrients 2020, 12, 988
  4. Britannica (2018). Cytokine.Available at: https://www.britannica.com/science/albumin, accessed: 12th October, 2020
  5. University of Birmingham (2020). Vitamin D deficiency increased risk of COVID in healthcare workers, new UK study. Available at: https://www.birmingham.ac.uk/news/latest/2020/10/vitamin-d-deficiency-increased-risk-of-covid-in-healthcare-workers-new-uk-study-shows.aspx, accessed: 12th October, 2020
  6. NHS (2020). Vitamin D.Available at: https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/ accessed: 12th October 2020

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