Low Vitamin D Levels Tied to Higher Odds for Severe COVID

FRIDAY, Sept. 25, 2020 (HealthDay News) -- Low blood levels of vitamin D might heighten people's odds for severe or even fatal COVID-19, new research shows.

Taking in a healthy level of vitamin D may therefore "reduce the complications, including the cytokine storm [release of too many proteins into the blood too quickly] and ultimately death from COVID-19," said study author Dr. Michael Holick. He's 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 manufactured naturally by the skin upon contact with sunlight. But it can also be sourced through certain foods and supplements.

One respiratory health expert who wasn't involved in the study said the findings echo those of prior research.

"Several studies have brought to light that patients with vitamin D deficiency have a worse outcome in COVID-19," said pulmonologist and internist Dr. Len Horovitz, of Lenox Hill Hospital in New York City. "This is not surprising since vitamin D seems to have a beneficial effect on the immune system and wound healing."

In the new study, 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, a type of immune cell that helps fight infection.

The study couldn't prove cause and effect. But 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 helping reduce 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.

But Horovitz noted that vitamin D might be a bit tougher to come by this year.

"During lockdown, people were indoors more and so their natural D level was lower than ever," he pointed out. "In people who don't take D, their level is usually low unless they take D as a supplement.

"I have been testing the level in all patients for years, and have found especially low levels since people have been indoors and quarantining," Horovitz said. "The dose is usually several thousand international units per day and can be tested with a blood test routinely."

More information

The Hormone Health Network has more on vitamin D.