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The Power of VItamin D

The sunshine vitamin

All you need to know about vitamin D from dietitian Dr. Linia Patel


Vitamin D is a vitamin that is completely different to most other vitamins. In fact, it is also known as prohormone. Vitamin D3 is produced from cholesterol when your skin is exposed to the sun, for this reason, vitamin D is often referred to as “the sunshine vitamin”

Does Vitamin D keep you healthy?


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. We know how that vitamin D is involved in more than just bone health. Infact, vitamin D deficiency is a silent epidemic. The symptoms are subtle and may take year or decades to surface.


Studies show that people with low vitamin D levels have a much greater risk of heart disease, diabetes, cancer, dementia and autoimmune disease like multiple sclerosis. 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.

What the link with Covid 19?


Evidence from the pandemic has shown us that populations with the highest risk of vitamin D deficiency are among those most affected by the virus. In the UK, a study in Birmingham showed that a higher percentage of the ethnic healthcare workers got Covid-19. In Stockholm, 40 % of the reported COVID-19 related deaths occurred in Somali communities, yet they represent less than 1% of the population. In the States, the African America populations also seem to have been hit the hardest. Where there are multiple reasons for this in relation to vitamin D, the darker your skin the more likely you are to have a vitamin D deficiency.


What the research on Vitamin D and immune health?


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.

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 Corona virus that those with normal levels of vitamin D. Another pilot randomized European clinical trial found that oral supplementation reduced the risk of ICU admissions by 93%.

So 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.

Who is at risk of 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 people who spend a lot of time indoors.

How to keep your 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 D3 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 D3 is also found in a small number of foods including oily fish, egg yolks, liver and vitamin D2 is found in wild mushrooms (or those exposed to UV light) and fortified foods (i.e. breakfast cereal). Another source of vitamin D is dietary supplements.


Government recommendations from the age of 1 years and onwards is that people take 10 micrograms (400IU) of vitamin D a day between October and early March.


If you take your blood results you can work with a dietitian or registered nutritionist to work out how best to keep your vitamin D blood levels optimal throughout the year.



  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 hospitalized for COVID19. A pilot randomized 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 Feb 2021
  5. Lanham New et al, Vitamin d and Sars CoV-2 virus/COVID-19 disease. Brief report. BMJ

Dr. Linia Patel

Linia is an award-winning dietitian and sports nutritionist. With a PhD in Public Health her passion is translating science into easy-to-digest and practical advice. She’s an active being and a total foodie.

IG: @liniapatelnutrition

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