A new study found that vitamin D levels are “severely low” in aging populations, particularly in Spain, Italy, and Switzerland. These countries have also experienced the greatest death rates due to COVID-19, prompting the authors to advise “vitamin D supplementation to protect against SARS-CoV-2 infection.”

Researchers at Queen Elizabeth Hospital Foundation Trust and the University of East Anglia analyzed the mean levels of vitamin D for 20 European countries, as well as data pertaining to the mortality rate caused by COVID-19.

Vitamin D is a fat-soluble vitamin that is naturally present in very few foods and available as a dietary supplement. It is also produced endogenously when ultraviolet rays from sunlight strike the skin and trigger vitamin D synthesis.

Previously, a 2017 meta-analysis of 25 randomized controlled trials involving over 11,000 participants confirmed that vitamin D supplementation can stave off acute respiratory infections.

It is highly likely that Vitamin D plays a protective role in Sars-CoV-2 infections, as well.

“Most people understand that vitamin D is critical for bone and muscle health,” said Carlos Camargo of the Department of Emergency Medicine at Massachusetts General Hospital (MGH) and the study’s senior author. “Our analysis has also found that it helps the body fight acute respiratory infection, which is responsible for millions of deaths globally each year.”

The authors of the new study found that the mean level of Vitamin D was about 56mmol/L. Vitamin D levels were correlated with the number of cases of COVID-19 per one million inhabitants in a population, as well as the number of deaths caused by COVID-19 per million people.

Mean values for vitamin D in the elderly population of Spain, Italy, and in Nordic countries were 26nmol/L, 28 nmol/L, and 45 nmol/L, respectively. Anything below 30nmol/L is classed as a severe deficiency in Vitamin D.

In Swiss nursing homes, mean vitamin D levels are 23 nmol/L. Switzerland has recorded 29,407 confirmed COVID-19 cases and 1,408 deaths. Just under half of those who have died in the canton of Ticino were residents of nursing homes, a recent report has shown.

“In conclusion, we found significant relationships between vitamin D levels and the number COVID–19 cases and especially the mortality caused by this infection. The most vulnerable group of population for COVID–19 is also the one that has the most deficit in Vitamin D. Vitamin D has already been shown to protect against acute respiratory infections and it was shown to be safe. We believe, that we can advise Vitamin D supplementation to protect against COVID–19 infection,” wrote the authors of the new study, which for now is published in a preprint server.

This is just the latest in a string of recent studies that have identified Vitamin D deficiency as a risk factor. An analysis performed by researchers from the Philippines of COVID-19 patients from three hospitals in Southern Asian countries found that critical cases were 19 times more likely in those with Vitamin D deficiency.

“An increase in serum (OH)D level in the body could either improve clinical outcomes or mitigate worst (severe to critical) outcomes. On the other hand, a decrease in serum (OH)D level in the body could worsen clinical outcomes of Covid-2019 patients. In this case, Vitamin D supplementation may play an important role to raise 1,25- dihydroxyvitamin D [1,25(OH)2D], the biologically active form of Vitamin D in the blood,” the authors wrote.

Vitamin D supplementation to keep the coronavirus at bay

Most adults need about 600 IUs (international units) of vitamin D per day while the elderly (over 70 years) are advised to intake 800 IUs per day. The biological activity of 40 IUs is equivalent to 1 microgram of Vitamin D.

We get our Vitamin D not only from what we eat but also from our own bodies when in contact with sunlight. A good Vitamin D-rich diet might include fortified milk and other dairy products, as well as sardines and other fish products which contain a high level of Vitamin D.

Since most countries across the world are now under lockdown, sunlight exposure is minimized, which is why people of all ages should supplement with Vitamin D, especially the elderly.