Researchers from Northwestern University found that infections and deaths were higher in countries where people had lower vitamin D levels.

"It will not prevent a patient from contracting the virus, but it may reduce complications and prevent death in those who are infected," researcher Vadi Backman says.

Getting enough vitamin D is an important part of keeping bones and muscle healthy - and some believe that it could help against coronavirus as well.

Photo: Effects of vitamin D on the body

At least two studies have found that there is a relationship between vitamin D deficiency and COVID-19 death rates.

A study in the UK found similar results. "Vitamin D has been shown to protect against acute respiratory infections, and older adults, the group most deficient in vitamin D, are also the ones most seriously affected by COVID-19," Lee Smith of Anglia Ruskin University wrote.

How your body makes vitamin D is an incredibly complicated process. In layman’s terms, your skin absorbs invisible Ultraviolet B (UVB) rays given off by the sun, and the liver and kidneys both play a part in taking those UVB rays and creating a form of vitamin D that’s usable by the body.