Vitamin D: Can the sunshine vitamin help to put Covid in the shade? 

Vitamin D helps our immune system to battle viral and other respiratory infections. So should we all be taking it as a supplement? Sharon Ní Chonchúir finds out
Vitamin D: Can the sunshine vitamin help to put Covid in the shade? 

Age, ethnicity, and obesity are all factors that have previously been associated with low levels of vitamin D. Picture: iStock

What would you do if you realised there was a cheap and widely available vitamin that might have the potential to protect us against becoming seriously ill with Covid-19 and help us to fight the virus?

This is a question that Dr Daniel McCartney, a lecturer in human nutrition and dietetics at the Technological University of Dublin, asked himself last year. His answer was to form the Covit-D Consortium with eight fellow medical professionals and academics from different specialist disciplines including respiratory medicine, immunology, geriatric medicine, endocrinology, biochemistry, molecular medicine, public health and nutrition and dietetics.

This group is now calling on the government to recommend a daily dose of 20 to 25 micrograms (mgs) of vitamin D for every Irish adult as a preventative treatment for Covid-19. They also want the government to provide vitamin D supplementation to vulnerable groups such as frontline healthcare workers, those with pre-existing conditions like diabetes and high blood pressure and older adults, especially those living in nursing homes.

“The Covit-D Consortium was founded in September 2020 when we knew the second wave was imminent,” says McCartney. “We were aware of ongoing research that seemed to show that vitamin D played a role in protecting people against becoming seriously ill with Covid-19 and could also be used to treat people once they did become ill. We felt it to be a professional, moral, and ethical imperative to act and call on the government based on our knowledge.” 

They have since compiled a position statement outlining the most up-to-date evidence showing the role vitamin D may play in bolstering the immune system’s response to Covid-19.

Firstly, they outline how the global medical community had observed that Covid-19 patients who are older, have darker skin, or are obese are more likely to require hospitalisation, be admitted to ICU, and die as a result of the virus.

“Age, ethnicity, and obesity are all factors that have previously been associated with low levels of vitamin D,” says McCartney. “This led medical professionals to ask if the nutrient might have a role to play in fighting Covid-19.” 

Reduced risk

Subsequent research appears to back up this theory. Swiss and Israeli studies showed that lower vitamin D levels appeared to be an independent risk factor for infection and hospitalisation with the virus. A German study showed that patients who were deficient in vitamin D were 15 times more likely to require intensive care treatment and six times more likely to die from Covid-19 than those with sufficient stores of the vitamin.

The same seems to be true here at home, with a pilot study in Connolly Hospital in Blanchardstown finding that Covid-19 patients with low levels of vitamin D were three times more likely to require ventilation.

Studies are also showing that vitamin D can also be used as a treatment for those hospitalised with the virus. In Cordoba in Spain, of 76, patients hospitalised with Covid-19, 50 received doses of activated vitamin D (a more potent form of the nutrient) and 26 didn’t. One patient from the group which received vitamin D was admitted to ICU compared with 13 from the control group, two of whom later died. This suggests a 25-fold reduced risk of ICU admission due to vitamin D.

A further study on 930 patients in a hospital in Barcelona had similarly positive results. 5.4% of the patients treated with activated vitamin D required ICU compared with 21.1% of the control group.

People in Ireland are at a disadvantage when it comes to vitamin D. Picture: iStock
People in Ireland are at a disadvantage when it comes to vitamin D. Picture: iStock

Sunshine vitamin

So, what exactly is vitamin D and how might it play a role in preventing and treating Covid-19?

“Vitamin D is sometimes called the sunshine vitamin,” says Louise Reynolds, a dietitian with the Irish Nutrition and Dietetics Institute. “Although we get some from our diet – especially from oily fish – we synthesise the majority of our vitamin D from UVB rays in the sunshine. As a fat-soluble vitamin, it is stored in our bodies and used up during the winter months.” We have long known that vitamin D is used to maintain healthy bones, teeth, and muscles but now there is widespread agreement that it plays a role in our immune system.

“It helps our immune system to resist viral and other respiratory infections and limit inflammation when infection does occur,” says McCartney. “This is vitally important as uncontrolled inflammation can lead to a cytokine storm, which is often what leads to severe outcomes and even death from Covid-19.” 

People in Ireland are at a disadvantage when it comes to vitamin D. “Because of where we are on the globe, the angle of the sun in winter means our skin can’t produce enough vitamin D between October and March,” says Reynolds.

According to the last national adult nutrition survey carried out in 2013, 55% of adults aged between 50 and 65 and 48% of those aged 65 to 84 were deficient in vitamin D in winter.

“The fact that we are all spending more time indoors during the pandemic increases our chances of being low in vitamin D even further,” says Reynolds.

 “It’s a particular risk for people with darker skin who need mark exposure to sunlight to make enough vitamin D and for older people, many of whom are spending more time indoors than ever before.” 

 Other countries are addressing vitamin D deficiency in their populations in a bid to limit the impact of Covid-19. Following the Cordoba study, public health authorities in Andalucía provided doses of activated vitamin D to all vulnerable older adults.

“This coincided with a decline in daily deaths in the region from 70 in mid-November to three by early January,” says McCartney. “This is all the more compelling when one considers the dramatic escalation in mortality which swept across Europe over the same period.” 

The conversation has also begun in Britain. Tory MP David Davis has championed the cause and Public Health England has responded by advising all adults to take a daily dose of vitamin D. The British government also promised to provide four months of free vitamin D supplementation to adults living in community and nursing home settings and in prison.

Finland is one country where such a conversation is unnecessary. It has been fortifying its liquid milks and spreadable fats with vitamin D sine 2003. In 2014, it also increased its recommended daily dose of the vitamin to levels likely to yield benefit in relation to immunological function, including doses of up to 20mgs a day for those aged over 75.

“Finland’s daily infection rates are much lower than Ireland’s and it has also experienced a considerably lower death rate [50,319 cases and 710 deaths as of February 14 compared with Ireland’s rates of 210,000 and 3948],” says McCartney. “It is eminently plausible that at least some of this apparent protection has been mediated by its vitamin D food fortification policy and well-communicated guidelines regarding supplementation.” 

Daily supplement

According to a statement from the Department of Health in Ireland, an evidence synthesis paper on vitamin D and Covid-19 was prepared for NPHET and considered at a meeting on January 28.

“NPHET agreed that efforts should be made to increase awareness of existing guidance [which is that adults aged 65 and overtake a 15mg daily supplement for bone and muscle health]; and that adults spending increased time indoors or housebound or in long-term residential care or have dark skin pigmentation are recommended to take a daily vitamin D supplement.” 

This was as far as the Department was willing to go.

 “At present, NPHET agrees that there is insufficient high-quality evidence with respect to vitamin D in the prevention and treatment of Covid-19,” says the spokesperson. “Ongoing developments, particularly randomised control trials in this area, will be monitored by NPHET with guidance reviewed accordingly.”

 Dr Laura Heavey, a specialist registrar in public health medicine with HSE Midlands, understands the Department of Health’s reluctance to endorse vitamin D as a protective measure. “The balance of evidence is not sufficient at this stage,” she says.

 "We need more large trials in different populations to be certain. There have been other treatments for Covid-19 – such as chloroquine – that turned out not be beneficial when they were evaluated as part of large clinical trials. We need to wait for results of ongoing randomised control trials to know for sure if vitamin D will really improve outcomes for those with Covid-19."

However, there is growing pressure on the government to act now, rather than waiting for irrefutable evidence. On February 11, Dublin-based Fine Gael TD Emer Higgins told the Dáil that there was "negligible risk and potentially massive gain" in making sure every adult in Ireland supplemented with vitamin D. She believed that delaying would result in lives being lost unnecessarily.

Daniel McCartney and the members of the Covit-D Consortium agree that there is no time to lose. "Ireland has lost more than 4,000 people to the pandemic to date," says McCartney. 

"At this time of crisis, we have nothing to lose and everything to gain if we make this harmless intervention. It's safe, cheap, and easily available and it may be very effective in preventing and treating Covid-19. At the very least, it will give us all healthier bones."

  • To read the Covit-D Consortium's position statement on vitamin D, click here.

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