Researchers at Northwestern University have discovered a strong connection between severe vitamin D deficiency and mortality rates after studying global data from the coronavirus disease 2019 (COVID-19) pandemic.

The research team conducted a statistical analysis of data from hospitals and clinics across China, France, Germany, Italy, Iran, South Korea, Spain, Switzerland, the United Kingdom, and the United States.

Findings from the data found that countries with high COVID-19 mortality rates, such as Italy and Spain, had lower levels of vitamin D compared with patients in countries that were not as severely affected. However, this does not mean that everyone needs to start hoarding supplements, according to the researchers.

“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,” said study lead researcher Vadim Backman, in a press release. “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.”

Backman and his team were interested in vitamin D levels after noticing unexplained differences in COVID-19 mortality rates between different countries. By analyzing publicly available data on patients from around the world, the researchers 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,” said study author Ali Daneshkhah, in the press release. “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.”

Not only does vitamin D enhance our innate immune systems, it also prevents our immune systems from becoming dangerously overactive, according to the study authors. This means that having a healthy level of vitamin D could protect patients against severe complications, including death, from COVID-19.

Backman said that this correlation may help explain the anonymity surrounding COVID-19 and children, as children do not yet have a fully developed acquired immune system.

“Children primarily rely on their innate immune system,” Backman said in the press release. “This may explain why their mortality rate is lower.”

The study authors noted that people should not take excessive doses of vitamin D due to the possibility of negative adverse effects. This topic needs further research to determine how vitamin D could be used most effectively to protect against COVID-19 complications, according to the study authors.


Vitamin D levels appear to play role in COVID-19 mortality rates. Northwestern University. Published May 7, 2020. Accessed May 13, 2020.