Popping vitamins and sitting in the sun became popular self-care practices during the pandemic. But doctors are still digging into the sunshine supplement’s supposed magic.

“Vitamin D is best known for building strong bones, but it also plays a pivotal role in the immune and respiratory systems, the main targets of SARS-CoV-2 and its developing variants. Only a handful of foods are naturally rich in the nutrient—oily fish, egg yolks, mushrooms, red meat, and liver—which is why it’s added to many cereals, milks, and juices post-process. ”