Why is Vitamin D Important to our Health?

vitamin d and sunshine

Let’s talk about Vitamin D, sometimes called “the sunshine vitamin”. During the COVID-19 pandemic there’s definitely a buzz around this vitamin. It is a well-known immune modulator. But can it really prevent COVID-19? And how can we ensure that we keep our vitamin D numbers in check?


Vitamin D has always been known to be important for healthy bones, teeth and muscles. A lack of it can lead to bone weakness or a deformity illness. This is known as rickets in children and in adults, osteomalacia. More recently, the focus on vitamin D has been its link to immune health. It has been suggested that vitamin D has a vital role in supporting healthy immunity and also in helping fight off infection.

Is there a link between vitamin D and COVID-19?

Evidence is emerging that populations with the highest risk of vitamin D deficiency are among those most affected by the disease. In the USA, the African American populations have contracted and died of coronavirus at an alarming rate. Whilst there are multiple reasons for this, one reason is thought to be their higher risk of vitamin D deficiency predisposing them to getting the virus.

In Stockholm too, for example, 40 % of the reported COVID-19 related deaths occurred in the country’s Somali communities, yet they represent less than 1% of the population. Being dark skinned, the Somali population in Sweden are also more likely to have a vitamin D deficiency. Similarly, in the UK, a study in Birmingham showed that a higher percentage of the BAME healthcare workers who got COVID-19.

can vitamin d stop covid-19

Can vitamin D help prevent contracting Coronavirus?

It is not true that vitamin D will protect you from the infection itself, and there is not enough clinical evidence to suggest that taking vitamin D will prevent you from catching the infection. However, it is certainly clear that the majority of the population would benefit from vitamin D supplementation. It is already the only supplement that the UK government recommends for general population consumption.

So now, more than ever, is an opportune time to consider introducing effective supplementation of vitamin D which may also have the additional effect of providing some protection from COVID-19 and its complications.


There has been a lot of research to suggest that having good vitamin D levels is helpful in the protection against RNA virus infections like the common cold, seasonal flu. Studies also suggest that vitamin D helps to fight illness in the least destructive way. People who become really sick from COVID-19 pneumonia are generally suffering from something called a cytokine storm. A cytokine storm is a disproportionate overreaction of the immune system that causes significant organ damage and can in some cases lead to death. The good news is that normal vitamin D levels have been associated with a reduction in cytokine storms. Though this is by no means conclusive, even an association like this must surely be a good thing.

However, despite the existing evidence of the link between vitamin D and immune health, in July of this year, the Scientific Advisory Committee on Nutrition (SACN) concluded that studies on using vitamin D for treating or preventing chest infections showed insufficient evidence to recommend supplementing with it. Based on this advice, the National Institute of Clinical Excellence (NICE) then suggested that there is no evidence to support taking vitamin D supplements to specifically prevent or treat coronavirus.

what does vitamin d effect

Interestingly, since the SACN conclusion a series of recently published studies specifically looking into COVID-19 concluded that vitamin D indeed can reduce the risk of developing COVID-19 as well as decrease the severity of the illness.

In one study from the University of Chicago for example, 489 patients at the hospital were studied, it was observed that those who were deficient in vitamin D were twice as likely to test positive for Coronavirus that those with normal levels of vitamin D. Another pilot randomised European clinical trial found that oral supplementation reduced the risk of ICU admissions by 93%.

who is at risk for vitamin d deficiency

Who is most at risk of a vitamin D deficiency?

  1. Those with pigmented skin who are less able to make the vitamin in their skin
  2. Those who are obese as this reduces their blood levels of vitamin D
  3. Those with high blood pressure and diabetes
  4. Those over the age of 50 years, when skin production is also reduced
  5. Those who are sun avoiders because of fair skin or lockdown!

In fact, before the pandemic, people in the UK were already advised to consider taking a vitamin D supplement from October to March. Now guidance is that vitamin D is needed throughout the year.

How to keep your vitamin D numbers in check

From about late March/early April to the end of September, most people should be able to get all the vitamin D they need from sunlight. The body creates vitamin D from direct sunlight on the skin when outdoors. But between October and early March in the UK we do not get enough vitamin D from sunlight.

Vitamin D is also found in a small number of foods including oily fish, egg yolks, liver and fortified foods (i.e. breakfast cereal). However, sunshine is still needed to convert the vitamin D naturally occurring in food (D2) into the functional form of vitamin D the body uses (D3). Another source of vitamin D is dietary supplements.

Government recommendations are that people take 10 micrograms of vitamin D a day. If you choose to take vitamin D supplements:

  • Children aged one to 10 should not have more than 50 micrograms a day
  • Infants (under 12 months) should not have more than 25 micrograms a day
  • Adults should not have more than 100 micrograms a day, with the recommended amount 10 micrograms a day

vitamin d supplements


Vitamin D has long been credited for healthy bones, teeth, and muscles. While research links vitamin D to our immune health in regards to warding off the illnesses like the seasonal flu and the common cold, having healthy levels of vitamin D will not protect you from contracting Coronavirus. However, the majority of the population would benefit from regular vitamin D supplementation. So keep vitamin D a regular part of your nutrition yearound, flu season or not.


  1. Brown et al. 2020. Preventing a COVID-19 pandemic. Rapid Response. BMJ. 368.
  2. Castillo et al. 2020. Effects of calcifediol treatment and best available therapy versus best available therapy on intensive care unit admission and mortality among patients hospitalised for COVID19. A pilot randomised clinical study. Journal of Steroid Biochemistry and Molecular Biology. Volume 203. 105751
  3. Faniyi A et al. 2020. Vitamin D status and seroconversion for COVID-19 in UK healthcare workers who isolated for COVID-19 like symptoms during the 2020 pandemic. Preprint.
  4. Department of Health UK. Insufficient evidence for vitamin D preventing or treating ARTI’s. Accessed on https://www.gov.uk/government/news/insufficient-evidence-for-vitamin-d-preventing-or-treating-artis
  5. Lanham New et al, Vitamin d and Sars CoV-2 virus/COVID-19 disease. Brief report. BMJ