Boston, MA—COVID-19 patients with a blood level of 25-hydroxyvitamin D—a measure of vitamin D—of at least 30 ng/mL, had a significantly decreased risk for adverse clinical outcomes including becoming unconscious, hypoxia, and death, according to a new study fromBoston University School of Medicine. The patients also had lower blood levels of an inflammatory marker and higher blood levels of lymphocytes, an immune cell that helps fight infection.

"This study provides direct evidence that vitamin D sufficiency can reduce the complications, including the cytokine storm (release of too many proteins into the blood too quickly) and ultimately death from COVID-19," explained corresponding author Michael F. Holick, Ph.D., M.D., Professor of Medicine, Physiology, and Biophysics and Molecular Medicine at BU School of Medicine, in the press release.

235 patients gave blood samples to be tested for vitamin D status, inflammatory markers, and lymphocytes. The researchers then followed those patients for clinical outcomes, and then compared the outcomes between patients with adequate vitamin D and patients who were vitamin D deficient.
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Vitamin D-sufficient patients older than 40 years were 51.5% less likely to die from infection than patients who were vitamin D deficient or insufficient.

Holick believes that being vitamin D sufficient helps fight consequences from other viruses causing upper respiratory tract illnesses, including influenza, as well as from coronavirus, the press release says. "There is great concern that the combination of an influenza infection and a coronal viral infection could substantially increase hospitalizations and death due to complications from these viral infections."

He added that vitamin D is a simple and cost-effective strategy to improve health: "Because vitamin D deficiency and insufficiency is so widespread in children and adults in the United States and worldwide, especially in the winter months, it is prudent for everyone to take a vitamin D supplement to reduce risk of being infected and having complications from COVID-19."