Vitamin D linked to reduced risk of coronavirus death, study suggests
Patients hospitalised with the coronavirus may endure less severe complications if their vitamin D levels are sufficiently high, research suggests.
The role of the sunshine supplement in warding off COVID-19, the disease caused by the infection, has been debated throughout the outbreak.
Vitamin D deficiency has been linked to an increased risk of viral respiratory infections in general, as well as inflammation.
When it comes to the coronavirus specifically, however, evidence was lacking.
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To learn more, scientists from Boston University took blood samples from 235 patients hospitalised with the infection.
Results revealed those with adequate vitamin D levels – defined as at least 30 nanograms (ng)/mL – were significantly less likely to become unconscious, develop dangerously low oxygen levels or die.
“This study provides direct evidence that vitamin D sufficiency can reduce the complications, including the cytokine storm (release of too many proteins into the blood too quickly), and ultimately death from COVID-19,” said study author Dr Michael Holick.
Cytokines are proteins released by the immune system to help fight an infection. Although generally a positive step towards recovery, some patients overproduce cytokines, leading to a “storm”.
The proteins may then mistakenly attack healthy tissue, which could result in organ failure.
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Vitamin D is an essential nutrient that helps keep bones, muscles and teeth healthy.
The NHS stresses “everyone should consider taking a daily supplement containing 10 micrograms of vitamin D during the autumn and winter”.
During the height of lockdown, Public Health England recommended people take vitamin D – despite the largely sunny weather – to counteract the effects of being housebound.
When it comes to warding off coronavirus complications, The Royal Society said in June “there is no direct causal link yet between vitamin D deficiency and increased susceptibility to COVID-19”.
The Scientific Advisory Committee on Nutrition echoed this, adding “overall, the evidence at this time does not support recommending vitamin D supplementation to prevent ARTIs [acute respiratory tract infections] in the general UK population”.
Dr Will Carroll from Keele University said at the time: “The best way to identify whether vitamin D has a role to play in helping the UK respond to the COVID-19 pandemic is to conduct a randomised clinical trial.”
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After measuring the vitamin D levels of 235 coronavirus patients, the Boston scientists found those with adequate amounts had reduced “clinical severity of the infection”.
Results – published in the journal PLOS One – revealed that in the patients over 40, those with sufficient vitamin D levels were 51.5% less likely to die with the infection than those whose levels were below 30ng/mL. One nanogram is one billionth of a gram.
Coronavirus cases are on the rise in the UK. On 24 September, 6,634 people tested positive for the infection, up from 3,395 the week before.
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Experts have expressed concern the NHS could become overwhelmed in winter, when seasonal flu is also circulating.
“There is great concern the combination of an influenza infection and a coronal viral infection could substantially increase hospitalisations and death due to complications from these viral infections,” said Dr Holick.
The scientists believe vitamin D supplements could be a simple, inexpensive way of reducing the risk.
“Because vitamin D deficiency and insufficiency is so widespread in children and adults in the United States and worldwide, especially in the winter months, it is prudent for everyone to take a vitamin D supplement to reduce risk of being infected and having complications from COVID-19,” said Dr Holick.
In response to the study, a spokesperson from the Department of Health and Social Care said: “The latest review from NICE [National Institute for Health and Care Excellence] suggests no robust evidence for vitamin D supplements reducing the severity of COVID-19.
“However, this is a new virus and we keep all strong evidence on treatments under review.”
How much vitamin D do I need?
Adults and children over one-year-old require 10 micrograms of vitamin D a day.
The same goes for pregnant women, breastfeeding mothers and people at risk of vitamin D deficiency, like those who are housebound.
One microgram is 1,000 times less than a milligram. Ten micrograms is often written as 10μg.
Babies under one need between 8.5μg and 10μg of vitamin D a day.
The Department of Health and Social Care recommends breastfed babies be given a supplement via liquid drops.
Formula milk is fortified with the nutrient, therefore babies fed this way should not be given vitamin D until they are having less than 500ml a day.
Foods that contain vitamin D – like oily fish, liver, egg yolks and fortified cereals or spreads – also help you stay topped up, however, it is difficult to get sufficient levels from diet alone.