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."
Backman is the director
of Northwestern's Center for Physical Genomics and Engineering and the
associate director for Research Technology and Infrastructure at the Robert H.
Lurie Comprehensive Cancer Center at Northwestern University. - Science
Daily
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