Lack of vitamin D might increase risk for COVID-19, University of Chicago researchers find

A lack of vitamin D may be associated with a higher risk for getting COVID-19, according to newly published research out of the University of Chicago.

Researchers looked at 489 patients tested for COVID-19 at University of Chicago Medicine between March 3 and April 10, whose vitamin D levels had been measured within a year of being tested for COVID-19.

Patients with untreated vitamin D deficiencies were 77% more likely to test positive for COVID-19 as patients with sufficient levels of the vitamin, according to the research, which was published Thursday in the peer-reviewed journal JAMA Network Open. The findings were reported earlier this year before the study was officially published.

“It raises the possibility that if you take vitamin D, you might be less likely to catch COVID,” said Dr. David Meltzer, chief of hospital medicine at University of Chicago Medicine and lead author of the study. “It’s very inexpensive. It could be used very broadly.”

Despite the link the study found between vitamin D and COVID-19, randomized clinical trials are needed to determine whether having a deficiency of the vitamin does in fact increase risk for the disease. Meltzer said he and his colleagues are launching trials in the Chicago area.

In the meantime, the study may have implications for people trying to protect themselves against COVID-19.

“Living in Chicago and knowing that a winter is coming, and we can’t all count on sunlight to give us all the vitamin D we need, it’s probably not an unreasonable thing for a lot of people to think about taking those minimal doses (of vitamin D) that get you to that recommended daily allowance,” Meltzer said.

People who have health conditions or take medications should consult a doctor before taking vitamin D supplements, Meltzer said. Too much vitamin D can cause a buildup of calcium in the blood, which can lead to nausea, vomiting, weakness, and frequent urination and eventually cause bone pain and kidney problems, according to the Mayo Clinic. It can take months of taking supplements or spending more time exposed to sunlight to correct a vitamin D deficiency, Meltzer said.

Even if subsequent research shows sufficient vitamin D levels make a person less likely to get COVID-19, people shouldn’t rely on vitamin D to protect them from the illness, he said.

“If someone takes vitamin D and then goes to a party thinking they’re not going to get COVID, they’ve made a mistake,” he said. “This is not a substitute for avoiding exposure.”

The paper said it may be particularly important to study the issue among Black and Latino people because, as groups, they tend to have high rates of vitamin D deficiency and have been disproportionately affected by COVID-19.

The study controlled for other health conditions that might have also put people with low levels of vitamin D at higher risk of COVID-19.