The value of vitamin D as a defence against Covid-19 infection

Background

Vitamin D helps to regulate the amount of calcium and phosphate in the body. These nutrients are needed to keep bones, teeth and muscles healthy.

Children who do not have sufficient levels of vitamin D in their body are at risk of bone deformities such as rickets whilst adults may experience bone pain caused by a condition called osteomalacia.[1]

The body creates vitamin D from direct sunlight on the skin when outdoors. Vitamin D is also found in a small number of foods including oily fish, red meat and fortified foods such as fat spreads and breakfast cereals.[2]

In the UK, most people should be able to produce sufficient vitamin D from sunlight between March and September. However, between October and March, people generally do not produce enough vitamin D.[3]

The National Institute of Health and Care Excellence (NICE) outlined the potential role of vitamin D with respect to Covid-19 infection:

Vitamin D is hypothesised to have a role in the immune response to respiratory viruses and can potentially mitigate the inflammatory response. During the COVID-19 pandemic, treatments are being explored as options for managing the disease. Therefore, it has been suggested vitamin D could improve outcomes in people diagnosed with confirmed COVID-19. [4]

Government guidance on vitamin D supplementation

In November 2020, Public Health England (PHE) and NICE issued guidance on vitamin D supplementation during winter.[5]

The guidance referred to reports about vitamin D potentially reducing the risk of Covid-19 and said, at the time, that there was “insufficient evidence to prove that it helps people respond to Covid-19, but as more evidence is accumulated, our understanding may change”.[6]

The guidance advised that everyone should take a supplement of vitamin D during winter months and set out the recommended dosage:

There are a range of products and doses available at supermarkets, pharmacies and other retailers; the recommended dose of vitamin D is 10 micrograms (400 International Units (IU)) per day. Taking more than this dose is not necessary, but if you are unable to find a vitamin D supplement providing 10 micrograms (400 IU), products providing up to 25 micrograms (1000 IU) are suitable for everyone.[7]

During the Covid-19 pandemic, the Government announced that it would offer free vitamin D supplements to clinically extremely vulnerable people and care home residents.[8] The Government acknowledged the higher risk of vitamin D deficiency due to the fact that these groups were likely to have spent more time indoors over the course of the year.[9]

An NHS webpage advises that the service for applying for free vitamin D supplements has now closed.[10]

Reviews and guidance on the role of vitamin D in Covid-19 infection

Public Health England (PHE), the Scientific Advisory Committee on Nutrition (SACN) and the National Institute of Health and Care Excellence (NICE) published an initial rapid review on vitamin D and acute respiratory tract infections (ARTIS) in June 2020,[11] followed by a December 2020 update.

The June 2020 review sought to:

• assess evidence from RCTs [randomised controlled trials] on vitamin D and risk of ARTIs published since the SACN report on vitamin D and Health (2016).
• consider if evidence on vitamin D and ARTIs published since the SACN report (2016) changes its previous conclusions on vitamin D and ARTIs[12]

Considering a range of academic research on vitamin D and ARTIs, the June 2020 review concluded that:

Overall, the evidence at this time does not support recommending vitamin D supplementation to prevent ARTIs in the general UK population. This conclusion does not impact on existing government advice on vitamin D […].[13]

In considering the research published after the June 2020 review, SACN’s December 2020 update reported that there “may be some benefit from daily, low dose vitamin D supplementation”.[14]

NICE guideline

In December 2020, NICE published its Covid-19 rapid guideline on vitamin D (NG187).[15]. NICE advised that people should consider taking a daily vitamin D supplement between October and early March, however the guideline warned against the use of vitamin D supplementation for the prevention or treatment of Covid-19:

1.2 Do not offer a vitamin D supplement to people solely to prevent COVID-19, except as part of a clinical trial.

1.3 Do not offer a vitamin D supplement to people solely to treat COVID-19, except as part of a clinical trial.[16]

[1] NHS, Vitamin D, accessed 14 Jun 2021

[2] Ibid

[3] Ibid

[4] NICE, Vitamin D for Covid-19, [A] Evidence reviews for the use of vitamin D supplementation as prevention and treatment of COVID-19, Dec 2020

[5] PHE, Statement from PHE and NICE on vitamin D supplementation during winter, 28 Nov 2020

[6] PHE, Statement from PHE and NICE on vitamin D supplementation during winter, 28 Nov 2020

[7] Ibid

[8] DHSC press release, At-risk groups to receive free winter supply of Vitamin D, 28 Nov 2020

[9] Ibid

[10] NHS, Free vitamin D supplements for people at high risk from coronavirus (Covid-19), accessed 14 Jun 2021

[11] SACN, Rapid review: Vitamin D and acute respiratory tract infections, Jun 2020

[12] Ibid

[13] Ibid

[14] SACN, Update of rapid review: Vitamin D and acute respiratory tract infections, Dec 2020

[15] NICE, COVID-19 rapid guideline: vitamin D NICE guideline [NG187], 17 Dec 2020

[16] Ibid