COVID-19 FAQ: Can vitamin D deficiency increase the risk or severity of the disease?


Recent scientific evidence suggests that adequate vitamin D levels can help reduce the risk of having more severe symptoms of the novel coronavirus infection.

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The link between vitamin D and the number of Covid-19-related deaths has been recently highlighted by an Irish study that looked at the vitamin D levels of adults in European countries. People can build up their vitamin D reserves through exposure to the sun and a lesser extent from food and supplements. Interestingly the start of the pandemic coincided with the winter and early spring period when inhabitants of the Northern hemisphere have the lowest level of vitamin D in their bodies. Surprisingly, despite the sunny climate the finding was valid for the people of Italy and Spain – both severely hit by the pandemic. Nordic countries, on the other hand, had fewer deaths and higher levels of the vitamin because according to the authors, more people take supplements there.

So, how does vitamin D temper Covid-19? There is now a significant body of research proving that appropriate levels of this vitamin can reduce the risk of viral acute respiratory infections. The SARS-CoV-2 virus mostly also attacks the lungs and a recent study conducted in Chicago has strongly argued that Covid-19 risk was linked to vitamin D deficiency. These studies prompted some speculation on social media about taking high doses of vitamin D pills. However, researchers writing in the British Medical Journal warned people that high intakes will not help and may even cause harm. They recommend taking vitamin D according to government-established guidelines, consuming a balanced diet and spending some time – but not more than is safe – in the sun to boost our vitamin D levels. With summer approaching in the Northern hemisphere, it remains to be seen if the pandemic will ease, due to people topping up their level of vitamin D and not because of rising temperatures – as explained in our earlier FAQ.

Here is the current state of science on a Sparrho pinboard. NB: The pinboard contains research papers that have not been peer-reviewed yet, meaning that they have not gone through the standard scientific validation process yet.


Endre Szvetnik

by Endre Szvetnik

Endre Szvetnik is Senior Editor at Sparrho. Endre works with Sparrho Heroes to curate, translate and disseminate scientific research to the wider public.

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