SCIENTISTS are weighing up whether vitamin D should be routinely prescribed on the NHS to at-risk patients as part of efforts to mitigate a second wave of Covid-19.

Studies suggest healthy levels of the so-called ‘sunshine nutrient’ may be key in stopping cases of the virus turning critical.

Now Public Health Scotland and NHS boards are putting the emerging evidence under the microscope to see if the hormone should be prescribed on the wards and to high-risk groups in society.

Research has shown that those most likely to be vitamin D-deficient – the elderly, ethnic minorities and the obese – are also those hit hardest by the pandemic.

The body makes the hormone when sun hits the skin so our cloudy climate puts us more at risk, but levels can be topped up with supplements and foods such as oily fish.

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Asked last week by Scottish Greens health spokesman Alison Johnstone MSP what plans the Scottish Government has to provide free vitamin D supplements to people at the highest risk from Covid, Public Health Minister Joe Fitzpatrick said the matter was “under active review”.

He said: “We recognise that the provision of vitamin D supplements is important for people who are shielding.”

Official Scottish Government guidance issued on June 3 states that everyone, including children, “should consider taking a daily supplement containing 10 micrograms of vitamin D”.

However, it is “specifically recommended” to all pregnant and breastfeeding women; infants and children under five years old; people from minority ethnic groups with dark skin such as those of African, African-Caribbean and South Asian origin, who require more sun exposure to make as much vitamin D; and people who are confined indoors.

Unprotected exposure to the sun outdoors, to generate vitamin D naturally, is also safe for up to 15 minutes, according to the guidance. Once sunscreen is applied, vitamin D production is blocked.

However, experts are now carrying out a “rapid synthesis of the existing evidence base on the need for vitamin D supplementation, over and above existing guidance on vitamin D supplementation, and the role high dose vitamin D may have in the treatment of people with Covid-19”.

Studies of hospital patients from around the world have shown that those with severe Covid-19 tend to be deficient in vitamin D while those with milder symptoms have healthy levels.

Singapore General Hospital now routinely gives coronavirus patients aged over 50 a mix of vitamin D, magnesium and vitamin B12 after spotting that those given a daily dose were eight times less likely to develop a serious illness.

Norway and Finland – countries of a similar size to Scotland – fortify basic foods like dairy products and encourage their populations to take supplements and have suffered less than 600 deaths between them compared with our death toll of around 2,500.

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New Zealand was just coming out of summer - when D levels are at their highest – as the pandemic hit in March and is now back to normal life with only 22 fatalities whereas more than half of Scots are deficient at the end of winter, according to official estimates.

The vitamin has been shown to protect against respiratory infection and also helps regulate the body’s immune reaction; many Covid-19 deaths occur when the body goes haywire in attacking the virus and ends up damaging major organs, a phenomenon known as the ‘cytokine storm’.

Robert Brown, of the nutrition think tank the McCarrison Society said: “The biological pathways by which vitamin D can help reduce severity of Covid-19 are well established and the real-life evidence from within this pandemic is growing.

“What’s needed now is for government to be bold and act now to mitigate the risk of a second wave returning in the winter.”

Vitamin D deficiency has also been linked to Scotland’s high rates of multiple sclerosis, as the condition appears to be more prevalent in countries with lower sunlight.

Recent research has discovered that the vitamin appears to affect how a gene linked to MS behaves, but research is still ongoing to determine whether supplements should be prescribed to patients with MS.

A PHS spokesman said the review of the evidence in relation to Covid was prompted by doctors seeking advice about whether to begin prescribing vitamin D to those at high risk of deficiency.

She added: “The evidence gathered will be used to assist and inform health professionals in answering questions being raised locally with them on the possible roles of vitamin D during the Covid-19 pandemic.”

It came as a cheap steroid treatment already used on the NHS emerged as a possible breakthrough in the fight against Covid.

Dexamethasone, described as “very boring drug” that’s been around for 60 years, was shown to cut mortality among coronavirus patients on ventilators from 40% to 28%. For patients needing oxygen, it cut the risk of death from 25% to 20%. Trials were carried out at 175 UK hospitals.

Had the drug had been used to treat patients in the UK from the start of the pandemic, it is estimated up to 5,000 lives could have been saved.

Peter Horby, chair of the NERVTAG advisory group and a professor of emerging infectious diseases who helped lead to trials by Oxford University, said the results were “quite remarkable”.

“Some people would say it’s a very boring drug, it’s been around for 60 odd years”, said Prof Hornby, adding that it would cost around £5 per person.

Boris Johnson said: “I’m absolutely delighted that the biggest breakthrough yet has been made by a fantastic team of scientists, right here in the UK.”

The UK has a stockpile of 200,000 courses of the drug and NHS England is to make dexamethasone available to patients.

Scotland’s interim chief medical officer, Dr Gregor Smith, welcomed the results which he said showed promise to “reduce the extreme elements of the inflammatory response”

He said: “We are currently working with the Department of Health and Social Care in England to see how we will use the dexamethasone that’s available in the UK for that purpose.”