There’s an association between vitamin D deficiency and the likelihood of becoming infected with COVID-19, according to a new retrospective study of people tested for COVID-19.
“Vitamin D is important to the function of the immune system and vitamin D supplements have previously been shown to lower the risk of viral respiratory tract infections,” says David Meltzer, professor of medicine and chief of hospital medicine at University of Chicago Medicine and lead author of the study in JAMA Network Open. “Our statistical analysis suggests this may be true for the COVID-19 infection.”
The research team looked at 489 patients whose vitamin D level had been measured within a year before being tested for COVID-19. Patients who had untreated vitamin D deficiency (defined as less than 20 nanograms per milliliter of blood) were almost twice as likely to test positive for COVID-19 compared to patients who had sufficient levels of the vitamin.
Researchers stress it’s important to note that the study only found the two conditions frequently seen together; it does not prove causation. Meltzer and colleagues plan further clinical trials.
Experts believe half of Americans have a vitamin D deficiency, with much higher rates seen in African Americans, Hispanics, and people living in areas like Chicago where it is difficult to get enough sun exposure in winter.
Research has also shown, however, that some kinds of vitamin D tests don’t detect the form of vitamin D present in a majority of African Americans—which means those tests might falsely diagnose vitamin D deficiencies. The current study accepted either kind of test as criteria.
COVID-19 is also more prevalent among African Americans, older adults, nursing home residents, and health care workers—populations who all have increased risk of vitamin D deficiency.
“Understanding whether treating vitamin D deficiency changes COVID-19 risk could be of great importance locally, nationally, and globally,” Meltzer says. “Vitamin D is inexpensive, generally very safe to take, and can be widely scaled.”
Meltzer and his team 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.
The University of Chicago/Rush University Institute for Translational Medicine Clinical and Translational Science Award and the African American Cardiovascular Pharmacogenetic Consortium funded the work.
Source: Gretchen Rubin for University of Chicago
