As scientists and doctors search for an effective COVID-19 treatment, we've been exploring the burgeoning science around staying healthy during this nightmare pandemic. Beyond tending to your overall metabolic health, we've been particularly interested in the connection between vitamin D and immunity—and researchers have recently found this is just the beginning.

We reported on a study in May that found those with vitamin D deficiencies have a higher risk of mortality from COVID-19, and now the first randomized clinical control trial of its kind found vitamin D supplementation can be effective in lowering the rate of COVID-19 intensive care unit (ICU) admissions.

The study, published in the Journal of Steroid Biochemistry and Molecular Biology, was conducted on 76 patients with COVID-19 pneumonia in Spain. The patients were split into two groups, and both received the same medical treatment based on hospital protocol. However, one group also received a daily Calcifediol supplement. The patients stopped taking the supplements when they were discharged from the hospital. 

Calcifediol, also called 25-hydroxyvitamin D, is a metabolite of vitamin D that appears in the blood and may help determine future health risks, according to new research from the European Society of Endocrinology. 

The supplement group was made up of 50 people, and only one (2% of participants) was admitted to the ICU. Additionally, all of the patients in the vitamin D group were discharged without complication or death from the virus.

Of the 26 patients in the control group, 13 (50%) were admitted to the ICU. Of those 13, two patients died and the other 11 were eventually discharged. 

It's important to note there is still no surefire treatment for the coronavirus. However, the study does show a strong potential correlation between vitamin D supplementation and a decrease in the severity of COVID-19 effects. 

"Our pilot study demonstrated that administration of a high dose of Calcifediol or 25-hydroxyvitamin D, a main metabolite of vitamin D endocrine system, significantly reduced the need for ICU treatment of patients requiring hospitalization due to proven COVID-19," the study authors write. 

Plus, those who are deficient in vitamin D are at an increased risk of developing cardiovascular disease, age-related brain diseases, osteoporosis, and autoimmune disorders. Regardless of its impact on COVID, vitamin D is critical for overall health. 

To get enough vitamin D when you can't go outside, be sure to eat plenty of vitamin-D-rich foods, such as salmon, mushrooms, tofu, and egg yolk or take an appropriate supplement.