NUTRITION AND THE INTENSIVE CARE UNIT: Edited by Peter Weijs and Stephen A. McClaveNutritional metabolomics in critical illnessChristopher, Kenneth B.Author Information Division of Renal Medicine, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, Massachusetts, USA Correspondence to Kenneth B. Christopher, MD, SM, Division of Renal Medicine, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA. E-mail: firstname.lastname@example.org Current Opinion in Clinical Nutrition and Metabolic Care: March 2018 - Volume 21 - Issue 2 - p 121-125 doi: 10.1097/MCO.0000000000000451 Buy Metrics Abstract Purpose of review Disruption of metabolic homeostasis is universal in the critically ill. Macronutrients and micronutrients are major environmental regulators of metabolite production through their gene regulation effects. The study of large numbers of circulating metabolites is beginning to emerge through the comprehensive profiling of the critically ill. In the critically ill, metabolomic studies consistently show that changes in fatty acids, lipids and tryptophan metabolite pathways are common and are associated with disease state and outcomes. Recent findings Metabolomics is now being applied in research studies to determine the critical illness response to nutrient deficiency and delivery. Nutritional metabolomics approaches in nutrient deficiency, malnutrition and nutrient delivery have included single time point studies and dynamic studies of critically ill patients over time. Integration of metabolomics and clinical outcome data may create a more complete understanding of the control of metabolism in critical illness. Summary The integration of metabolomic profiling with transcription and genomic data may allow for a unique window into the mechanism of how nutrient deficiency and delivery alters cellular homeostasis during critical illness and modulates the regain of cellular homeostasis during recovery. The progress and the challenges of the study of nutritional metabolomics are reviewed here. Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.