We’ve made it to December of 2020, a year that nobody could have predicted and certainly one that none of us could have prepared for. We here at Sunlight Nutrition sincerely hope you are all keeping yourselves as well as you can be.

We continue to see headline after headline about COVID-19 and it can be draining and overwhelming. We too have been keeping an eye on these headlines and thought we would share some information regarding the role of vitamin D during the COVID-19 pandemic. In these early days when there is little research and data available, advice is constantly changing. It can be difficult to separate fact from fabrication and evidence from opinion. This can leave us feeling confused and uncertain. So here we will discuss the current guidance and research in terms of vitamin D and COVID-19 and try to make the available evidence clear and concise. So let’s start at the beginning..

What is Vitamin D and what does it do?

This is a fat soluble vitamin which we all need to protect our bones, teeth and muscles. It has been suggested that vitamin D may have a part to play in the bodies reaction to respiratory infections. This idea has not been proven so currently the use of vitamin D to prevent or treat infections (including COVID-19) is not recommended or licenced.

Where do we get Vitamin D?

Vitamin D is mostly made in the skin in response to sunlight, and so it is known as the ‘sunshine vitamin’. Here in the UK there is a significant difference in sunlight exposure throughout different seasons. Public Health England advises that in spring and summer months most of the population can achieve the recommended daily allowance of vitamin D through sunlight and by following a healthy balanced diet.

During autumn and winter when there is less sunlight and we spend more time indoors- it can be difficult to get all the vitamin D we need from food. Because of this, Public Health England recommend that everybody takes a vitamin D supplement containing 10 micrograms of vitamin D per day.
Some people are more vulnerable to not achieving daily vitamin D recommendations. For example populations with darker skin tones, those whose skin does not get enough sunlight exposure as it is covered by clothing or those who spend all their time indoors. They recommend that these groups should consider taking a vitamin D supplement all year round (1).

Good food sources of vitamin D include oily fish (salmon, mackeral, sardines), red meat, liver, egg yolks and foods which have been fortified with vitamin D (some spreads, cereals, dairy products) (2).

What do the headlines suggest?

There have been many claims about the role of vitamin D and coronavirus. It has been reported by some sources, including newspapers, that vitamin D supplementation can be protective against corona virus, treat the virus or can reduce severity of coronavirus infection.

What’s its relevance to COVID? Why do they think it helps?

As we’ve already mentioned, it has been suggested that vitamin D plays a role in how our bodies respond to infections and that it has an influence on the immune system. This idea has been around long before COVID-19 emerged, but there is not yet clear evidence or guidance on its application.

The Evidence

In 2016 The Scientific Advisory Committee on Nutrition (SACN) published a large report on the role of vitamin D on human health. It explored a large and reliable spectrum of evidence. There is some published evidence that vitamin D supplementation reduces risk of respiratory tract infections and there are also some scientific papers which report that there is no association between vitamin D and risk of infections. What does this mean? Essentially it means that there has not been enough convincing and consistent evidence to make recommendations for the use of vitamin D to reduce risk of infections, and currently that includes COVID-19 (3).

There was a large evidence review (2016) which found that vitamin D supplementation did not reduce risk of respiratory infections (4). Another large meta-analysis published in the British Medical Journal back in 2017 found that vitamin D supplementation was protective against respiratory tract infections. This paper reported that those who were initially deficient in vitamin D experienced the most benefit (5). It has since been found that there were a number of limitations to this 2017 research and a review by SACN (2020) found that the recommendations are not applicable to the general population (6). The most recent SACN recommendations (2020) highlight that maintaining healthy vitamin D status is important for musculoskeletal health. They have not made any recommendations on vitamin D for COVD-19.

There are known associations between variations in individuals vitamin D status, time of year and the prevalence of respiratory infections. It has been proposed that lower vitamin D status in winter is associated with increased respiratory infections eg. the common cold. It is however so important that when we look at associations between different factors, that we are mindful that an association does not mean causality. For example, there is an association between umbrellas and rain, but that does not mean that umbrellas cause rain.

In June 2020 NICE also produced a rapid evidence summary regarding the matter in response to claims about vitamin D and COVID-19. They stated that there is currently no evidence to support the theory that taking vitamin D supplements is beneficial to specifically to prevent or treat COVID-19. It recommended that the public continues to take daily vitamin D supplements to maintain bone and muscle health (1).

The NHS are now providing a service for free vitamin D supplements for those at high risk from COVID-19 (those who have been advised to ‘shield’). This is because if these individuals have spent the majority of their time indoors during the summer, they are at higher risk of vitamin D deficiency this winter. The government have not stated that these free supplements are available to reduce risk of corona virus.

This year there has been a large amount of investigation into the potential role of vitamin D and COVID-19, and this research is ongoing. There is currently no evidence to make any recommendations. It has been reported that in October the Health Secretary formally asked for updated guidance from NICE on the use of vitamin D in COVID-19, but no such publication has been made yet.

In conclusion, for many years there has been a suggestion that vitamin D has an important role to play in the bodies immune response to infections, but there has not been sufficient evidence or proof of this. There is a theory and it has been reported in many headlines that vitamin D may also play an important role in managing the COVID-19 pandemic, but the latest guidance from NICE and SACN report that there is no evidence to back this. Both bodies recommend that the population continues to take 10 micrograms of vitamin D per day this winter to maintain good bone and muscle health.

We hope this has been a helpful breakdown of the evidence behind the recent headlines. As always, we encourage you to look beyond the claims, think critically about what you read and source of your nutrition information carefully.

Take care.

The Sunlight Nutrition Team.

Written by Katie O’Callaghan

References

  1. Public Health England (2016) ‘PHE New Advice on Vitamin D’ Available at : https://www.gov.uk/government/news/phe-publishes-new-advice-on-vitamin-d
  2. Lamberg-Allardt (2006) ‘Vitamin D in Food and as Supplements’ Progress in Biophysics and Molecular Biology, Volume 92, Issue 1. Available at : https://www.sciencedirect.com/science/article/abs/pii/S0079610706000071?via%3Dihub
  3. Scientific Advisory Committee on Nutrition (2016) ‘Vitamin D and Health’ Available at: https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/537616/SACN_Vitamin_D_and_Health_report.pdf.
  4. Vuichard Gysin et al (2016) ‘Effect of Vitamin D3 Supplementation on Respiratory Tract Infections in Healthy Individuals: A Systematic Review and Meta-Analysis of Randomized Controlled Trials’. Available at: https://pubmed.ncbi.nlm.nih.gov/27631625/
  5. Martineau et al (2017) ‘Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data’ British Medical Journal, Volum 356, Issue 6583. Available at: https://www.bmj.com/content/356/bmj.i6583.
  6. Scientific Advisory Committee on Nutrition (2020) ‘Rapid Review: Vitamin D and Acute Respiratory Tract Infections’ Available at: https://app.box.com/s/g0ldpth1upfd7fw763ew3aqa3c0pyvky