COVID-19 rapid guideline: vitamin D

This guideline covers vitamin D use in the context of COVID19. It is for adults, young people and children in hospitals and community settings. Vitamin D is important for bone and muscle health. It may also have a role in the body's immune response to respiratory viruses.

# Recommendations
Encourage people to follow UK government advice on taking a vitamin D supplement to maintain bone and muscle health. The advice is that:
Adults (including women who are pregnant or breastfeeding), young people and children over 4 years should consider taking a daily supplement containing 10 micrograms (400 units; also called international units ) of vitamin D between October and early March because people do not make enough vitamin D from sunlight in these months.
Adults, young people and children over 4 years should consider taking a daily supplement containing 10 micrograms (400 units) of vitamin D throughout the year:
if they have little or no sunshine exposure including because they:
are not often outdoors, for example, if they are frail, housebound or living in a care home
usually wear clothes that cover up most of their skin when outdoors
are spending most of their time indoors because of the COVID19 pandemic
if they have dark skin, for example, if they are of African, African-Caribbean or south Asian family origin, because they may not make enough vitamin D from sunlight.
Babies from birth to 1 year should have a daily supplement containing 8.5 micrograms (340 units) to 10 micrograms (400 units) of vitamin D throughout the year if they are:
breastfed
formula-fed and are having less than 500 ml of infant formula a day (because infant formula is already fortified with vitamin D).
Children aged 1 year to 4 years should have a daily supplement containing 10 micrograms (400 units) of vitamin D throughout the year.
Some people have a medical condition that means they cannot take vitamin D or should take a different amount from the general population.
Do not offer a vitamin D supplement to people solely to prevent COVID19, except as part of a clinical trial.
This recommendation has been replaced by recommendation 7.15 in NICE's COVID-19 rapid guideline on managing COVID-19.
For a short explanation of why we made these recommendations see the rationale section on recommendations .
Full details of the evidence are in the evidence review.
Loading. Please wait.# Rationale

# Why the panel made the recommendation
The panel agreed that there was little evidence for using vitamin D supplements to prevent COVID19. However, they agreed that vitamin D use is well established for maintaining bone and muscle health. They expressed concerns that not everyone is aware of, or is following, UK government advice on taking a vitamin D supplement, so wanted to include a recommendation to emphasise the existing guidance. They stressed that everyone should consider taking a supplement containing 10 micrograms (400 units) of vitamin D daily between October and early March, when people in the UK do not make enough vitamin D from sunlight. They also stressed that this was particularly important during the COVID19 pandemic, when people may have been indoors more than usual over the spring and summer.
The panel discussed that, for most people, 10 micrograms (400 units) of vitamin D a day will be enough to prevent serum 25(OH)D concentration from falling below 25 nmol/litre. They also noted that taking too high a dose of vitamin D over a long period of time could be harmful because it can cause too much calcium to build up in the body (hypercalcaemia). This can weaken the bones and damage the kidneys and the heart. They were aware that the tolerable upper intake level for adults and young people over 11 years is 100 micrograms (4,000 units) daily, and that this dose should not be exceeded. They discussed monitoring requirements if people have renal impairment or high doses are given, and were aware of cautions for use in people with certain medical conditions, such as sarcoidosis. They agreed that, if people are unsure whether they can take vitamin D, they should discuss this with their healthcare professional. The panel also discussed that vitamin D3 (colecalciferol) supplements can be derived from an animal source. They noted that people's concerns about using animal products because of a religious or ethical belief need to be considered when discussing vitamin D products.
The panel also noted that it is important for some populations to take a supplement containing 10 micrograms (400 units) of vitamin D daily throughout the year. This includes people who are at a higher risk of not getting enough vitamin D because, for example, of lack of exposure to sunlight during the spring and summer months.
The panel discussed access to vitamin D supplements, and were aware of the NICE guideline on vitamin D: supplement use in specific population groups and the NHS service supplying free daily vitamin D supplements for people at high risk (clinically extremely vulnerable) from COVID19. This service has been set up because it is particularly important for people who have been indoors more over the spring and summer when shielding to take vitamin D for bone and muscle health.

## Preventing COVID-19
The panel were presented with evidence from the NICE evidence review of vitamin D for COVID-19 on using vitamin D supplements to prevent SARSCoV2 infection (and subsequent COVID19), and evidence on vitamin D status and its association with COVID19.
No evidence relevant to the protocol was found for the prevention question. The panel discussed the evidence for the association of vitamin D status with COVID19. They agreed that low vitamin D status was associated with more severe outcomes from COVID19. However, it is not possible to confirm causality because many of the risk factors for severe COVID19 outcomes are the same as the risk factors for low vitamin D status. Vitamin D is a negative acute phase reactant, meaning its serum concentration falls during a systemic inflammatory response, which may occur during severe COVID-19 illness. Therefore, it is difficult to know if low vitamin D status causes poorer outcomes or vice versa.
The panel discussed the significant limitations in the retrospective association studies. These included historic and inaccurate vitamin D status measurements, lack of generalisability to UK practice, the likelihood of confounding and general low quality of the evidence.
Because COVID19 mainly affects the respiratory tract, the panel also heard indirect evidence from the updated Scientific Advisory Committee on Nutrition (SACN) rapid review on using vitamin D supplements to prevent acute respiratory tract infections. They agreed that a systematic review and meta-analysis by Jolliffe et al. (2020) reported a modest protective effect of vitamin D supplementation compared with placebo. From subgroup analyses, this protection was associated with daily doses of 10 micrograms to 25 micrograms (400 units to 1,000 units) of vitamin D, but not higher doses. Also, from subgroup analysis, the protection was only seen in children and young people aged from 1 year to under 16 years (the panel noted that, for COVID19, poorer outcomes are more common in an older adult population). Beneficial effects on acute respiratory tract infection prevention were not seen with higher doses of vitamin D supplementation (over 25 micrograms  daily or more), when supplementation was weekly or monthly, or in adults. The SACN rapid review highlighted limitations with the studies included in the meta-analysis by Joliffe et al. (2020) including:
inconsistency between study results
differences between studies in vitamin D supplementation doses and regimens, settings, populations, durations and definitions of outcomes (including type of respiratory infection).
The panel were also aware of the updated SACN recommendations that a vitamin D intake of 10 micrograms (400 units) daily, as currently recommended, may provide some additional benefit in reducing the risk of acute respiratory tract infections. However, they noted that this topic is being kept under review and these recommendations may be updated if findings from robust, high-quality randomised controlled trials provide further clarification.
Based on direct evidence from the NICE evidence review and indirect evidence from the SACN rapid review of vitamin D in acute respiratory tract infection (which did not include COVID19 as an outcome), the panel agreed that there was not enough evidence to recommend vitamin D supplements solely for preventing COVID19.
The panel agreed that people should be encouraged to follow the existing UK government advice on vitamin D supplementation. They also agreed that the recommendations in this guideline on vitamin D supplements and COVID19 prevention should be considered for an update as additional evidence becomes available.
The panel agreed that there is a need for research into vitamin D supplementation for preventing COVID19. However, they discussed issues around ethics, trial design and comparators, and agreed that it would be more appropriate for the research community to define an appropriate PICO (population, interventions, comparators, outcomes) framework. They were aware that the updated SACN rapid review on using vitamin D supplements to prevent acute respiratory tract infections has a recommendation that research is urgently needed on vitamin D and risk of acute respiratory tract infection in black, Asian and minority ethnic groups, and people living with overweight or obesity. The panel also noted that several randomised controlled trials of vitamin D supplements in preventing COVID19 are known to be in progress.
As additional evidence becomes available, this guidance will be updated in line with NICE's interim process and methods for guidelines developed in response to health and social care emergencies.
Full details of the evidence are in the NICE evidence review of vitamin D for COVID-19.
Return to recommendations# Context
Vitamin D is important for bone and muscle health. It may also have a role in the body's immune response to respiratory viruses. Sunlight exposure is the main source of vitamin D for most people in the UK during summer months. But, between October and early March, people in the UK do not make enough vitamin D from sunlight. Vitamin D is also found in a small number of foods and can be obtained from supplements. The 2 key forms of vitamin D, D3 (colecalciferol) and D2 (ergocalciferol), are licensed for preventing and treating vitamin D deficiency. They are not specifically licensed for preventing any infection, including SARSCoV2 that causes COVID19.
Vitamin D status is determined by measuring serum concentrations of 25 hydroxyvitamin D (25D), the major circulating metabolite of vitamin D. Existing UK government recommendations on vitamin D are based on advice from the Scientific Advisory Committee on Nutrition (SACN). To protect bone and muscle health, the SACN vitamin D and health report recommends that serum 25(OH)D concentration should not fall below 25 nmol/litre at any time of the year. To achieve this, SACN recommends a reference nutrient intake of 10 micrograms (400 units; also called international units ) of vitamin D daily for the UK population aged 4 years and above. This is the average amount needed by 97.5% of the population to maintain a serum concentration of 25 nmol/litre when UVB sunshine exposure is minimal. UK government advice on taking a vitamin D supplement includes:
micrograms (400 units) of vitamin D daily for everyone in the UK aged over 4 years between October and early March, and
micrograms (400 units) of vitamin D daily throughout the year for people whose serum 25(OH)D concentrations may not reach 25 nmol/litre through sunlight alone.
The dose of vitamin D in units can be calculated by multiplying the number of micrograms by 40; for example, 10 micrograms is equivalent to 400 units. This guideline uses 'units' instead of 'international units' or 'IU' for doses of vitamin D. This is consistent with the BNF guidance on prescription writing, and stems from the preferred convention of using 'units' because of safety concerns about using 'IU' in prescribing.
There are services supplying free vitamin D supplements to some population groups. For example, there is an NHS service supplying free daily vitamin D supplements for people at high risk (clinically extremely vulnerable) from COVID19. This service has been set up because it is particularly important for people who have been indoors more over the spring and summer while shielding to take vitamin D for bone and muscle health. Women and children who qualify for the Healthy Start scheme can also get free supplements containing vitamin D.