The review came to the same conclusion as NICE’s first rapid evidence summary in June this year and said that more research was needed to determine the effectiveness of vitamin D supplementation in treating or preventing COVID-19.
This latest analysis was undertaken by NICE, in conjunction with Public Health England and the Scientific Advisory Committee on Nutrition, at the request of health secretary Matt Hancock.
NICE said it had looked at ‘the best available scientific evidence published so far, including both observational studies and randomised controlled trials’. It found it was ‘not possible to determine a direct relationship between vitamin D and COVID-19’.
Low vitamin D levels
The experts contributing to the review did agree that low vitamin D levels were linked to more severe outcomes from COVID-19. However, the review said it was not ‘possible to confirm causality because many of the risk factors for severe COVID-19 outcomes are the same as the risk factors for low vitamin D status’.
Current government advice is for everyone to take a vitamin D supplement during the autumn and winter, which NICE backed. It said that everyone should take a daily 10 microgram vitamin D supplement from October to early March.
NICE also recommends that those with dark skin and people who are frail or housebound – and therefore at risk of not obtaining enough vitamin D from sunlight even in summer – should take a vitamin D supplement year-round.
However the institute said there was not currently enough evidence to support taking vitamin D ‘solely to prevent or treat COVID-19’.
‘Due to the lack of reliable evidence on the effects of the supplement on COVID-19, our guidance recommends that more research be conducted on the subject, stressing the use of high-quality randomised controlled trials in future studies,’ NICE said.
Vitamin D and COVID-19
The review looked at published evidence on vitamin D supplements for preventing or treating COVID-19, any links between vitamin D status and COVID-19 and indirect evidence on taking the supplement for preventing acute respiratory tract infections. It also took advice from specialists working across the UK.
Last month the government announced that patients who are clinically extremely vulnerable to COVID-19 (those on the shielding list) and care home residents would be provided with free vitamin D for four months starting in January.
Dr Paul Chrisp, director of the Centre for Guidelines at NICE, 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.’