New research has found that people with severe vitamin D deficiency are twice as likely to experience major COVID-19 complications…

Northwestern University-led research analyzed COVID-19 patient data from 10 countries – China, France, Germany, Italy, Iran, South Korea, Spain, Switzerland, the United Kingdom (UK) and the United States – and found a correlation between low vitamin D levels and hyperactive immune systems.

Vitamin D strengths innate immunity and prevents overactive immune responses. The finding could explain several mysteries, including why children are unlikely to die from COVID-19.

What does this mean for you?

This does not mean that everyone needs to start hoarding supplements, the researchers caution.

“While I think it is important for people to know that vitamin D deficiency might play a role in mortality, we don’t need to push vitamin D on everybody,” says Northwestern’s Vadim Backman, who led the research. “This needs further study, and I hope our work will stimulate interest in this area. The data also may illuminate the mechanism of mortality, which, if proven, could lead to new therapeutic targets.”

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Backman adds that excessive doses of vitamin D might come with negative side effects. He said the subject needs much more research to know how vitamin D could be used most effectively to protect against COVID-19 complications.

“It is hard to say which dose is most beneficial for COVID-19,” says Backman said. “However, it is clear that vitamin D deficiency is harmful, and it can be easily addressed with appropriate supplementation. This might be another key to helping protect vulnerable populations, such as African-American and elderly patients, who have a prevalence of vitamin D deficiency.”

Why researchers looked at vitamin D

Backman and his team were inspired to examine vitamin D levels after noticing unexplained differences in COVID-19 mortality rates from country to country.

Some people hypothesized that differences in healthcare quality, age distributions in population, testing rates or different strains of the coronavirus might be responsible. But Backman remained sceptical.

“None of these factors appears to play a significant role,” says Backman. “The healthcare system in northern Italy is one of the best in the world. Differences in mortality exist even if one looks across the same age group. And, while the restrictions on testing do indeed vary, the disparities in mortality still exist even when we looked at countries or populations for which similar testing rates apply.

“Instead, we saw a significant correlation with vitamin D deficiency,” he says.

Low vitamin D levels linked to a cytokine storm

By analyzing publicly available patient data from around the globe, Backman and his team discovered a strong correlation between vitamin D levels and cytokine storm – a hyperinflammatory condition caused by an overactive immune system – as well as a correlation between vitamin D deficiency and mortality.

Cytokine storm can severely damage lungs and lead to acute respiratory distress syndrome and death in patients. This is what seems to kill a majority of COVID-19 patients, not the destruction of the lungs by the virus itself. It is the complications from the misdirected fire from the immune system,” explains Ali Daneshkhah, a postdoctoral research associate in Backman’s laboratory, is the paper’s first author.

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Vitamin D enhances the immune system

This is exactly where Backman believes vitamin D plays a major role. Not only does vitamin D enhance our innate immune systems, but it also prevents our immune systems from becoming dangerously overactive.

This means that having healthy levels of vitamin D could protect patients against severe complications, including death, from COVID-19.

“Our analysis shows that it might be as high as cutting the mortality rate in half,” says Backman. “It will not prevent a patient from contracting the virus, but it may reduce complications and prevent death in those who are infected.

This may explain why kids are less affected

Backman says this correlation might help explain the many mysteries surrounding COVID-19, such as why children are less likely to die.

Children do not yet have a fully developed acquired immune system, which is the immune system’s second line of defence and more likely to overreact.

“Children primarily rely on their innate immune system,” says Backman. “This may explain why their mortality rate is lower.”

Source: Northwestern University via

Natural sources of vitamin D include sunshine, fatty fish and seafood, mushrooms and egg yolk. Source:

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