NUTRITION AND THE INTENSIVE CARE UNIT: Edited by Peter J.M. Weijs and Stephen A. McClaveVitamin D supplementation in the ICU patientChristopher, Kenneth B.Author Information The Nathan E. Hellman Memorial Laboratory, Renal Division, Brigham and Women's Hospital, Boston, Massachusetts, USA Correspondence to Kenneth B. Christopher, The Nathan E. Hellman Memorial Laboratory, Renal Division, Brigham and Women's Hospital, 75 Francis Street, MRB 418, Boston, MA 02115, USA. Tel: +1 617 272 0535; e-mail: [email protected] Current Opinion in Clinical Nutrition and Metabolic Care: March 2015 - Volume 18 - Issue 2 - p 187-192 doi: 10.1097/MCO.0000000000000147 Buy Metrics Abstract Purpose of review Recent findings suggest that vitamin D is a marker for outcomes in critical illness. The purpose of this review is to summarize current biological, observational and interventional evidence in the critically ill. Recent findings Both biological and observational studies support the role of vitamin D deficiency in adverse critical illness outcomes. Interventional trials of critically ill patients show that to improve vitamin D status, high-dose vitamin D3 is required. Critically ill patients have a relatively blunted response to vitamin D supplementation compared to the general outpatient population. Toxicity from high-dose vitamin D in trials in the critically ill has been limited to mild hypercalcemia. Recent evidence suggests that treatment of severely vitamin D-deficient critically ill patients with high-dose vitamin D early in the ICU course may improve mortality. Summary Vitamin D deficiency is a potentially modifiable marker for adverse outcomes in critical illness and critical illness survivors. Vitamin D supplementation is inexpensive and appears safe in critical illness trials. A well powered interventional trial is required to determine the definitive answer regarding the role of vitamin D supplementation in the improvement of critical care outcomes. Until such data are available, a cautious approach to correction of vitamin D status in the ICU is warranted. Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved.