Study finds vitamin D deficiency may increase COVID-19 risk

Researchers at the University of Chicago Medicine found an association between vitamin D deficiency and the likelihood of becoming infected with the novel coronavirus (COVID-19), according to a new retrospective study published in JAMA Network Open.

For the study, researchers looked at 489 patients whose vitamin D level was measured within a year before being tested for COVID-19. Patients who had vitamin D deficiency, less than 20 ng/ml, that was not treated were almost twice as likely to test positive for the COVID-19 coronavirus compared to patients who had sufficient levels of the vitamin.

Half of Americans are deficient in vitamin D, with much higher rates seen in Blacks, Hispanics, and individuals living in areas like Chicago where it is difficult to get enough sun exposure in winter.

The research team said they emphasize the importance of experimental studies to determine whether vitamin D supplementation can reduce the risk, and potentially severity, of COVID-19. They also highlight the need for studies of what strategies for vitamin D supplementation may be most appropriate in specific populations. They also said they have initiated several clinical trials.

“Understanding whether treating vitamin D deficiency changes COVID-19 risk could be of great importance locally, nationally, and globally,” said David Meltzer, MD, PhD, lead author of the study and Chief of Hospital Medicine, in a statement. “Vitamin D is inexpensive, generally very safe to take, and can be widely scaled.”

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