Vitamin D supplementation has shown promise for reducing mortality in the intensive care setting. It is one of the newest medicines to be tested in ICU departments. Improved vitamin D status decreases the odds of all cause-mortality. There is a high prevalence of vitamin D deficiency in the critically ill patient populations. We have several intensive care unit studies which have demonstrated an association between vitamin D deficiency [25-hydroxyvitamin D (25(OH)D) < 20 ng/mL] and increased hospital length of stay (LOS), readmission rate, sepsis and mortality.
There was a significant decrease in hospital length of stay over time in 250,000 IU and the 500,000 IU vitamin D3 groups, compared to the placebo group. Vitamin D is known to have pleiotropic effects on patients immune pathways and may be uniquely involved with lung immune function and alveolar capillary barrier function. (See Light Deficiency as a Cause of Cancer)
“I visited a level I trauma care center where they have been using high-dose vitamin D for about ten years. I interviewed the chief surgeon. He is the one who told me that vitamin D is the most powerful medicine he uses. He said, "In my hospital vitamin D flows like water." They give every patient on admission 50,000 IU and continue that for 5-7 days. He told me they are still in awe of all of the lives they are saving with vitamin D. He said that a lot of the lives are being saved because vitamin D is the most powerful anti-inflammatory agent they have ever seen. Of course he also said that it superchargers the immune system. They refuse to do a placebo-controlled study because he said it would be unethical since everyone is benefiting from the vitamin D. They could not ethically deprive people of vitamin D to have a placebo group.”
On Medscape you will read High-Dose Vitamin D Shows Promising Effects in MS, and at the same time you will read Critically ill patients who are vitamin D deficient do not seem to gain any benefit from the administration of high-dose vitamin D in the intensive care unit, results from a phase 3 randomized trial indicate. You will read similar studies on Vitamin C as the mainstream struggles to repress anything and everything non-pharmaceutical.
 J Clin Transl Endocrinol. 2016 Jun; 4: 59–65. High dose vitamin D administration in ventilated intensive care unit patients: A pilot double blind randomized controlled trial.