A new study that looked at 216 people with COVID-19 found that 80 percent didn’t have adequate levels of vitamin D in their blood.

The study also found that people who had both COVID-19 and lower vitamin D levels also had a higher number of inflammatory markers such as ferritin and D-dimer, which have been linked to poor COVID-19 outcomes.

A different study found that COVID-19 patients who had adequate vitamin D levels had a 51.5 percent lower risk of dying from the disease and a significant reduced risk for complications.

Medical experts theorize that maintaining adequate vitamin D levels may help lower risk or aid recovery from severe COVID-19 for some people, though more testing is needed.