New research shows insufficient blood levels of vitamin D might heighten people's odds for severe or even fatal COVID-19.
Maintaining a healthy level of vitamin D may "reduce the complications, including the cytokine storm (release of inflammatory proteins into the blood too quickly) and ultimately death from COVID-19," according to the study author Dr. Michael Holick. Dr. Holick is a professor of medicine, physiology, biophysics and molecular medicine at Boston University School of Medicine.
Vitamin D is called the "sunshine vitamin" because it's produced by a cholesterol compound in the skin when skin is exposed to sunlight. But it can also be sourced through certain foods and supplements.
The findings build upon those of prior research.
Several studies have found that patients with vitamin D deficiency have a worse outcome in COVID-19. Vitamin D has a beneficial effect on the immune system.
Holick and his colleagues assessed vitamin D levels in blood samples from 235 hospitalized COVID-19 patients. The blood samples were also checked for an inflammatory marker called C-reactive protein and for the number of lymphocytes, (immune cells that fight infections.)
Patients who were vitamin D-sufficient -- a blood level of at least 30 nanograms per milliliter -- had a significantly lower risk for serious complications from COVID-19, including losing consciousness, low blood oxygen levels and death.
Among patients older than 40, those who were vitamin D-sufficient were also 51.5% less likely to die from COVID-19 compared to those who were vitamin D-deficient or insufficient, the team said.
The study was published Sept. 25 in the journal PLOS ONE.
A prior study by Holick found that having a sufficient amount of vitamin D might also reduce the risk of becoming infected with the new coronavirus by 54%. Along with reducing the risks associated with the new coronavirus, being vitamin D-sufficient does the same against other viruses that cause upper respiratory tract illnesses, including the flu, according to Holick.
"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 said in a university news release.
All in all, vitamin D could offer a simple and cost-effective way to combat the new coronavirus, Holick believes. "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," he said.
In people who don't take D, the level is usually low, so it may make sense to take D as a supplement. A blood test will reveal your level of vitamin D. Supplements should be in the most bioavailable form of vitamin D, vitamin D-3. A typical adult dose is 4000 to 5000 iu daily.