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Vitamin D And COVID-19: Everything You Need To Know

1st Jun, 2021  |  Claire O'Brien  |  News

If you felt under the weather as a kid, you may remember your parents or grandparents telling you to “go outside and get some sunshine”.

While this may easily have been written off as an old wives tale, the role between vitamin D and your immune system is now at the top of everyone’s mind, especially with the emergence of studies linking vitamin D and milder COVID-19 symptoms.

Among other things, vitamin D contributes to calcium and phosphorus absorption, it plays a role in the process of cell division and most importantly it contributes to maintaining a healthy immune system,

Since the global pandemic was declared in March 2020, many studies have been conducted into the link between COVID-19 and vitamin D.

In this guide we’re going to break down some of the most interesting studies, and explain why they are interesting. We’ll also go in depth on:

  • The link between the groups worst affected by COVID-19 and vitamin D
  • Which countries are most at risk of being vitamin D deficient
  • The advice major governments have given when it comes to vitamin D and COVID-19

We’ll also explore a number of other key issues and answer some of the questions you may have about COVID-19 and vitamin D

Chapter 1

The Relationship The Relationship Between COVID-19 & Vitamin D


When the COVID-19 pandemic was declared by the World Health Organisation (WHO), governments across the world were worried that their health systems would buckle under the pressure as each world leader announced sweeping lockdowns across their countries.

The race was on to find a way to treat the disease and many scientists started to explore effective treatments.

When exploring data on patients with COVID-19, a link started to emerge between vitamin D deficiencies and more severe COVID-19 symptoms.

In April 2020 a study emerged that explored vitamin D deficiencies and the implications for COVID-19.

Another study was published in the Irish Medical Journal in May of 2020 exploring the link between vitamin D and COVID-19, and a study was also published in the British medical journal the same month.

With even more data becoming available as the months went on, many more studies have been published throughout 2020 and 2021 exploring the relationship between the virus, the disease and vitamin D.

Chapter 2

What Studies Have Discovered About COVID-19 & Vitamin D


The aforementioned April study from Trinity College in Dublin, explained that in Ireland 149,000 adults have a vitamin D deficiency and 244,200 adults are deficient in winter (more than 5% of the population).

The study went on to explore the role of vitamin D in supporting a strong immune system and also looked at the vitamin D status of people who were obese and those with respiratory lung conditions.

The study also noted that of the 244,200 adults that were vitamin D deficient, nearly 30% of those aged 70+ were in the age group considered to be extremely medically vulnerable to the adverse health outcomes of COVID 19.

The study went on to conclude that “Vitamin D is a potent immune modifying micronutrient and if vitamin D status is sufficient, it could benefit vulnerable adults in particular those 70+ years and older who are ‘cocooning’ during the COVID-19 outbreak.”

Another study from the Irish Medical Journal hypothesized that “vitamin D status may influence the severity of responses to COVID-19 and that the prevalence of vitamin D deficiency in Europe will be closely aligned to COVID-19 mortality.”

Using a literature search on Pubmed, they explored the vitamin D status for older adults in European countries that were most affected by COVID-19 infection.

Interestingly the study reported that sunny countries such as Spain and Italy had low concentrations of vitamin D and high rates of vitamin D deficiency.

The study concluded that optimising vitamin D status to nationally and internationally recommended allowances would strongly benefit bone health and had potential benefits for COVID-19:

“There is a strong plausible biological hypothesis and evolving epidemiological data supporting a role for vitamin D supporting the immune system and the helping with the fight against COVID-19 infection”

Another study on the effects of vitamin D on COVID-19 advised that “People admitted to hospital with COVID-19 should have their vitamin D status checked and/or supplemented and consideration should be given to testing high-dose calcifediol in the recovery trial”

Chapter 3

How Vitamin D Supports Your Immune System


According to the Irish Medical Journal, vitamin D has been shown to support the immune system and may reduce the risk of respiratory infection.

“Correction of vitamin D deficiency is thought to boost the immune system. Vitamin D may help with immune inflammatory responses, in patients including those with COVID-19.”

Low Vitamin D has been linked to muscle weakness and brittle bones, according to Dr Laura Lenihan.

“Known as ‘the sunshine vitamin’, Vitamin D is essential for the maintenance of normal bones and teeth, as it contributes to normal blood calcium levels. And, as it is a fat-soluble vitamin, it can be stored in the body for a long time”, Dr Lenihan explains.

The core function of Vitamin D is in regulating absorption of calcium and phosphorous and also plays a role in the normal function of the immune system and inflammation responses, according to the GP.

Chapter 4

The Demographics Worst Affected By COVID-19


According to the HSE (Health Service Executive of Ireland) there are 2 levels of higher risk when it comes to COVID-19, high risk and very high risk.

The very high risk group includes people who:

  • Are over the age of 70
  • Have down syndrome
  • Have cancer
  • Are on dialysis or have a kidney disease
  • Have conditions that affect the brain or nerves
  • Have severe asthma
  • Have uncontrolled diabetes
  • Have had an organ or bone marrow transplant
  • Have sickle cell disease
  • Are obese with a BMI above 40

The high risk group includes people over the age of 60, people with milder forms of the diseases mentioned above, as well some other conditions.

As well as these conditions, a link has also been found between more severe symptoms of COVID-19 and groups of ethnic minorities.

One study found that people who are dark skinned are more likely to be vitamin D deficient.

The study explains that darker skinned people need even more sun that light skinned people to achieve vitamin D photosynthesis.

“In a cohort study of 16 180 from the USA showed that the prevalence of vitamin D deficiency (less than 30 nmol l−1) was 17.5% in non-Hispanic black compared with 2.1% in non-Hispanic whites”

Another paper from the national economic and social council studied the key impacts of COVID-19 on ethnic minority and migrant groups in Ireland. This paper explained that:

“Recent research suggests that Black, Black Irish, Asian, Asian Irish and Traveller groups are more likely to contract COVID-19 than those who are White Irish. This may be linked to their occupation and housing conditions. The death rates are lower than those of the White Irish group, which may be related to the younger age profile of these ethnic minority groups.”

Chapter 5

Governments Advice On Vitamin D?


While nearly all governments have recommended that their citizens should supplement with vitamin D in the winter at the very least, it seems that none of them specifically stated that increasing vitamin D levels would help the immune system fight against COVID-19, or that higher levels of vitamin D were linked to less severe COVID-19 symptoms.

In the UK the NHS offered free vitamin D to vulnerable groups but stopped short of recommending it specifically for COVID-19.

The UK’s official government advice on vitamin D and COVID-19 at the time of writing is that:

“vitamin D is needed to keep bones and muscles healthy. It has also been suggested that vitamin D could reduce the risk of and COVID-19. As yet, there is insufficient evidence to prove that it helps people respond to COVID-19, but as more evidence is accumulated, our understanding may change.

There are currently trials underway which we are keeping a close eye on. In the meantime, people should follow the current UK government advice on vitamin D supplementation to support general health, in particular bone and muscle health.”

In Ireland, one politician citing numerous studies, (some of which we’ve already mentioned)

implored the government to follow the lead of their UK counterparts and offer free vitamin D to vulnerable groups

Another Politician in Ireland urged that the minister for health should “be brave enough to make a decision to recommend people start taking vitamin D.”

Outside of government advice the pandemic also resulted in changes to cultural nom’s.

In Indonesia for example, the link between vitamin D and COVID 19 resulted in cultural shifts with one report stating that Indonesian people usually tended to avoid the sun and did not want to get a sun-tan, but now anyone from soldiers to housewives have started sun-bathing regularly.

Chapter 6

The Best Sources Of Vitamin D?


Now that we’ve studied the relationship between vitamin D and COVID-19, you are probably wondering what the best sources of vitamin D are.

The best source of vitamin D is of course sunlight.

According to the NHS (The National Health Service in the UK) from March until September most people are able to make all the vitamin D they need from sunlight (although those of us lucky enough to live in on the British Isles might not agree with that!)

They advise that “between October and early March we do not make enough vitamin D from sunlight.”

So what can you do if you don’t get enough sunlight?

The NHS advises that vitamin D can be found in some foods, including

  • Oily fish – such as salmon, sardines, herring and mackerel
  • Red meat
  • Liver
  • Egg yolks
  • Fortified foods – such as some fat spreads and breakfast cereals

They also advise that dietary supplements are another great source of vitamin D.

An article from the Cleveland Clinic offers similar advice, stating that “sunlight (in moderation), supplements and food sources can help get your numbers up to where they should be.”

Vitamin D and COVID-19: Conclusion

So that’s our ultimate guide to vitamin D and COVID-19.

We hope we helped your knowledge on the significant studies that link vitamin D to supporting your immune system in the fight against COVID-19, the groups that are most at risk from COVID-19 and how you can increase your intake of vitamin D.

So now it’s over to you. Did we miss anything along the way? Or maybe there’s something that you liked about this guide? Let us know and get in touch via our social channels!

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