Low vitamin D levels might increase a person’s odds of a severe bout with COVID-19, a new study says.

People with a vitamin D deficiency are 36% more likely to require hospitalization from a COVID infection, researchers report in the journal PLOS One.

“Vitamin D plays a key role in regulating the immune system, so it’s plausible that low levels may influence how the body responds to infections like COVID-19,” investigator Kerri Beckmann, a senior research fellow at the University of South Australia, said in a news release.

However, the study also found no increased risk of COVID infection among people with low vitamin D levels.

“Our study found that people with a vitamin D deficiency or insufficiency were more likely to be hospitalized with COVID-19 than those with healthy levels of Vitamin D – but they weren’t more likely to catch the virus in the first place,” Beckmann said.

About 1 in 5 (22%) of Americans are vitamin D deficient, according to a 2022 study published in Frontiers in Nutrition.

For the study, researchers analyzed data from more than 150,000 people participating in UK Biobank, a long-range study of health in the United Kingdom.

The team looked at the risk COVID poses among people who are either fully vitamin D deficient or have insufficient levels of the vitamin and compared it to risk seen among their counterparts who have normal levels of vitamin D.

Results indicate that vitamin D levels could contribute to better COVID outcomes, in much the same way that vaccine boosters play a role.

“COVID-19 may not be the threat it once was, but it still affects peoples’ well-being,” Beckmann said. “Understanding who is most at risk helps those individuals take extra precautions, including monitoring their vitamin D levels.”

It could be that people who are in poor health to begin with may also have low vitamin D levels, she notd.

“So, at this stage, we don’t know whether vitamin D supplements in themselves could reduce the severity of COVID-19,” Beckmann continued.  “It’s certainly an area worth exploring – especially as we continue to live with the virus.”