One study, which was peer reviewed and published in the journal Critical Care, looked at lung epithelial cells in a lab as well as animals and humans in clinical settings. They determined that a dietary-induced vitamin D deficiency led to lung inflammation and damage. In the clinical study, all of the patients who suffered from ARDS were found to have a vitamin D deficiency, which is defined as blood levels that are less than 50 nmol/L. Moreover, patients with extremely low levels of vitamin D – which was defined as being below 8 ng/mL – had a 3.5 times greater likelihood of developing ARDS than people whose levels were above 8. Thankfully, correcting their vitamin D levels reduced the lung damage and led to improved survival rates.