Key TakeawaysLow vitamin D levels might increase the odds of severe COVIDPeople with low blood levels of vitamin D deficient were 36% more likely to be hospitalized with COVIDHowever, vitamin D levels were not related to overall infection risk.FRIDAY, July 25, 2025 (HealthDay News) — 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.”More informationThe Cleveland Clinic has more on vitamin D.SOURCE: University of South Australia, news release, July 21, 2025 .What This Means For YouMake sure your vitamin D levels are sufficient — especially when there is an outbreak of COVID..Sign up for our weekly HealthDay newsletter