After studying global data from the novel coronavirus (COVID-19)
pandemic, researchers have discovered a strong correlation between severe
vitamin D deficiency and mortality rates.
Led by
Northwestern University, 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 (UK) and the United States.
The researchers
noted that patients from countries with high COVID-19 mortality rates, such as
Italy, Spain and the UK, had lower levels of vitamin D compared to patients in
countries that were not as severely affected.
This does not
mean that everyone — especially those without a known deficiency — 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,” said
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.”
The research is
available on medRxiv, a preprint server for health sciences.
Backman is the
Walter Dill Scott Professor of Biomedical Engineering at Northwestern’s
McCormick School of Engineering. Ali Daneshkhah, a postdoctoral research
associate in Backman’s laboratory, is the paper’s first author.
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 skeptical.
“None of these
factors appears to play a significant role,” Backman said. “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 said.
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,” Daneshkhah said. “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.”
This is exactly
where Backman believes vitamin D plays a major role. Not only does vitamin D
enhance our innate immune systems, 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,” Backman said.
“It will not prevent a patient from contracting the virus, but it may reduce
complications and prevent death in those who are infected.”
Backman said
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
defense and more likely to overreact.
“Children
primarily rely on their innate immune system,” Backman said. “This may explain
why their mortality rate is lower.”
Backman is
careful to note that people should not take excessive doses of vitamin D, which
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,” 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.”
Journal article: https://www.medrxiv.org/content/10.1101/2020.04.08.20058578v3
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