Vitamin D: low-risk treatment could reduce Covid deaths

The sunshine hormone, vitamin D, is in the spotlight once again as a potential coronavirus treatment.

Debates over the benefits of this age-old substance to treat Covid have raged for months, but they’ve intensified this week after the striking results of a Spanish trial.

Yet as the findings are met with further scepticism, it remains unclear how much closer we are to approving a safe, cheap and potentially highly effective defence against Covid-19.

The trial in question, published by the Social Science Research Network, involved 930 Covid patients hospitalised in the wards of the Hospital del Mar in Barcelona. Upon admission, 551 of the group received an intensive dose of calcifediol – a vitamin D metabolite. The remaining 379 patients acted as a control group.

The reported effect of calcifediol was remarkable: those who received the drug were 74 per cent less likely to be admitted to intensive care and 60 per cent less likely to die.

David Davis MP – who has been a staunch advocate of Vitamin D throughout the pandemic – has called for the government to take immediate action: “The findings of this large and well-conducted study should result in this therapy being administered to every Covid patient in every hospital in the temperate latitudes.”

“Since the study demonstrates that the clear relationship between vitamin D and Covid mortality is causal, the UK government should increase the dose and availability of free vitamin D to all the vulnerable groups,” he told Reaction.

The findings build upon a smaller pilot trial in Cordoba, conducted earlier this year, in which calcifediol treatment reduced ICU admissions by 50 per cent in hospitalised Covid patients. Several other observational studies have also drawn links between vitamin D deficiency and poor Covid outcomes. And large studies conducted before coronavirus have concluded that taking vitamin D supplements can reduce flu and pneumonia symptoms.

A number of medical professionals are keen to raise awareness of the benefits of the drug for treating Covid. Professor Parag Singhal, a North Somerset physician, has urged those from Black, Asian and minority ethnic backgrounds, who suffer disproportionately from vitamin D deficiencies, to take daily doses of the sunshine hormone. “It’s estimated that 90 per cent of people from BAME backgrounds are vitamin D deficient,” he said. “My message to the BAME population is clear and loud. Please take an adequate dose of vitamin D – develop your defensive immunity to minimise the severity of the disease.”

Yet the UK government has shied away from explicitly promoting vitamin D as a coronavirus treatment, instead calling for research on it to be “kept under review’. The National Institute for Health and Care Excellence (NICE) has said there is insufficient causal evidence to support giving vitamin D in high doses to hospitalised patients.

Vitamin D advocates had hoped that the Barcelona research might provide a turning point. However, in past few days, the study – which is yet to be peer-reviewed- has been criticised for its design, particularly its control group and patient allocation.

“Some dramatic positive findings are presented,” says Prof Naveed Sattar, Professor of Metabolic Medicine at the University of Glasgow, “but important methodological details are missing. The abstract mentions randomisation – but methods do not describe how the randomisation was done.”

Similarly, Prof Adrian Martineau, Clinical Professor of Respiratory Infection and Immunity at Queen Mary University of London, voiced concern about the disproportionately small control group and lack of placebo. “We must await robust randomised trials to form appropriate conclusions [on vitamin D],” he said.

Dr Perry Wilson, director of the Clinical and Translational Research Accelerator, has questioned the decision to divide patients into the two trial groups according to which hospital ward they were in. But he suggests that the problem could be remediated if missing data is released that clears up ambiguities: “The authors could solve this by releasing a de-identified dataset – including the ward number – for this study.”

However, as the trial generates demands for further proof and the debate rumbles on, it raises the question: at what point should we acknowledge that, while evidence may not be entirely “conclusive”, encouraging individuals to up their dosage of vitamin D carries little risk and potentially a large gain?

“We are wasting precious time,” says Davis, who believes the drug, which costs “pennies a pill” and is easy to prescribe, could save thousands of lives. “The sadness will be that we’ll get to a ‘conclusion’ after the pandemic is over.”

Irrespective of Covid, the government encourages people to take 10 micrograms (400 IU) of vitamin D daily for bone strength during the winter months. This winter, it launched an initiative to offer 2.7 million vulnerable individuals in England a free winter supply of vitamin D while they spend more time indoors.

But those who believe that the drug could help us fend off Covid say this isn’t nearly enough. In order to benefit from its immune strengthening properties, “we should be taking around 10 times more than the recommended dose,” says Davis. Alongside 200 other doctors and public figures, he signed a letter in December calling for the government and health bodies to increase their recommended daily vitamin D intake to 4000 IU.

Despite apparent flaws in the Barcelona study, Davis is still hopeful that the trial will help to move things forward. Indeed, in the past week, Matt Hancock has asked his advisors to look at the vitamin D findings again, says Davis.

Purported coronavirus cures must be treated with caution. And concerns about patchy trial designs demand attention. But, as long as the uncertainty over vitamin D rages on, we may be wasting the opportunity to benefit from a safe and potentially very useful treatment.