There is not enough evidence to support taking vitamin D solely to treat or prevent Covid-19, a rapid review of clinical evidence has concluded.

The review, carried out by NICE, Public Health England and the Scientific Advisory Committee on Nutrition, was ordered by health secretary Matt Hancock following reports of links between vitamin D deficiency and severe Covid-19.

Anticipating the results, Mr Hancock already announced that millions of vulnerable people in England would receive free supplies of Vitamin D for the winter.

But the guidance, published today, advises healthcare professionals ‘not to offer vitamin D supplements to people solely to [prevent or treat] Covid-19, except as part of a clinical trial’.          

However, it also underlines that people should be encouraged ‘to follow the UK government advice on taking a vitamin D supplement to maintain bone and muscle health’.

The document says: ‘[The panel] 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.’

The guidance also recommends more research is carried out into ‘the clinical effectiveness of vitamin D supplements for treating Covid-19 in adults, young people and children’ because ‘of the lack of reliable evidence of the effects on the supplement’.

It suggests ‘randomised controlled trials in all care settings with a minimum 8-week follow up’ and ‘a particular focus on subgroup analyses’ such as age, ethnicity and comorbidities associated with poorer outcomes in people with Covid-19.

The panel also agreed that there is a need for research into vitamin D supplementation for preventing Covid-19. They found ‘low vitamin D status was associated with more severe outcomes from Covid-19′, but stressed it is ‘difficult to know if low vitamin D status causes poorer outcomes or vice versa’.

Director of the Centre for Guidelines at NICE Dr Paul Chrisp said: ‘While there is insufficient evidence to recommend vitamin D for the prevention or treatment of Covid-19 at this time, we encourage people to follow government advice on taking the supplement throughout the autumn and winter period.

‘As research continues on the impact of vitamin D on Covid-19, we are continuing to monitor evidence as it is published and will review and update the guidance if necessary.’

The guidance follows a study published yesterday by the University of Australia that found ‘alarmingly high’ levels of vitamin D deficiency in the UK.

Of almost half a million people surveyed, 57% of Asians and 38.5% of black Africans living in the UK are severely deficient in vitamin D in winter and spring. White Europeans were the least affected at 17.5%.

Vitamin D is required for the maintenance of healthy bone and muscle. Although sunlight exposure is the major source of vitamin D for most people during summer months, it can also be obtained from diet or supplements.

Last month, a Spanish study found more than 80% of hospitalised Covid patients had a vitamin D deficiency.

Covid-19 rapid guideline: Vitamin D

1.1 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 [IU]) 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 COVID-19 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.

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.

Source: NICE

A version of this story was first published on our sister publication, Nursing in Practice.