Outcomes of Vitamin D supplementation in adults who are deficient and critically ill: A review of the literature

Vitamin D deficiency is known to be common in the general population and has been linked to allcause mortality. The classically recognized role of Vitamin D is its involvement in calcium and phosphorous homeostasis and bone health. Recent evidence suggests that Vitamin D may also play a role in other nonskeletal processes, such as anti-proliferation, immunity, regulation of hormone section, and muscle strength. An extensive literature review of Vitamin D and critical illness from 2000 to 2015 (PubMed and CINAL) produced multiple observational studies revealing a high prevalence of Vitamin D deficiency in intensive care patients. Many of these studies have indicated that there is an association between Vitamin D deficiency and clinical outcomes such as mortality, sepsis, duration of mechanical ventilation, and length of stay. This review article provides an overview of Vitamin D physiology in adults, a summary of observational studies on Vitamin D deficiency in critical illness, and an examination of the few clinical trials on Vitamin D supplementation in intensive care patients.