Personalized Nutrition Strategies for Patients in the Intensive Care Unit: A Narrative Review on the Future of Critical Care Nutrition

Abstract

Introduction: Critically ill patients in intensive care units (ICUs) are at high risk of malnutrition, which can result in muscle atrophy, polyneuropathy, increased mortality, or prolonged hospitalizations with complications and higher costs during the recovery period. They often develop ICU-acquired weakness, exacerbated by sepsis, immobilization, and drug treatments, leading to rapid muscle mass loss and long-term complications. Studies indicate that adequate protein and calorie intake can decrease mortality and improve prognosis and recovery. However, optimal implementation remains a critical challenge. Objectives: This narrative review aims to summarize recent advances in nutritional strategies for critically ill patients. It highlights the benefits and limitations of current approaches including enteral (EN) and parenteral nutrition (PN) and examines their impact on clinical outcomes and overall mortality. Additionally, the review explores the emerging role of precision nutrition in critical care using technologies such as metabolomics and artificial intelligence (AI) to provide valuable insights into optimizing nutritional care in critically ill patients. Methods: A comprehensive literature search was conducted to identify recent studies, clinical guidelines, and expert consensus papers on nutritional support for ICU patients. The investigation focused on critical aspects such as the optimal timing for intervention, the route of administration, specific protein and energy targets, and technological innovations to support personalized nutrition, ensuring that each patient receives tailored support based on their unique needs. Results: Guidelines recommend initiating EN or PN nutrition within the first 48 h of admission, using indirect calorimetry (IC) to estimate energy needs, and supplementing protein up to 1.2 g/kg/day after stabilization. IC has gained importance in assessing energy needs but is still underused in the ICU. EN is preferred because it maintains intestinal integrity, reduces the risk of infections, and is recommended within the first 48 h of ICU admission. PN is used when EN is infeasible, but it increases the risk of infection. By integrating metabolomics with transcriptomic and genomic data, we can gain a deeper understanding of the effect of nutrition on cellular homeostasis, facilitating personalized treatments and enhancing the recovery of critically ill patients. Conclusions: AI is becoming increasingly important in monitoring and evaluating artificial nutrition, providing a more accurate and efficient alternative to traditional methods. AI can assist in identifying and managing malnutrition and is effective for estimating caloric and nutrient intake. AI minimizes human error, enables continuous monitoring, and integrates various data sources. The nutritional care of critically ill patients requires collaboration among specialists from diverse fields, including physicians, nutritionists, pharmacists, radiologists, IT experts, and policymakers.

Keywords: critical illness; enteral and parenteral nutrition; metabolic diseases; metabolome; nutritional genomics; personalized nutrition.

Figure 1

Critical decisions in patients’ nutrition in ICU involve balancing various therapeutic options. On one side of the scale are methods of enteral and parenteral nutrition, the timing of artificial nutrition administration, the use of indirect calorimetry versus simple predictive formulas, and the choice between hypocaloric and hypercaloric nutrition, as well as continuous versus intermittent feeding, personalized versus standardized approaches to nutrition. On the other side are biomarker tests versus nutrigenomics and the use of artificial intelligence for nutrition monitoring versus classical monitoring methods. These dilemmas represent essential challenges in selecting the optimal nutritional treatment for critically ill patients, depending on their clinical conditions and available resources.

Figure 2

The figure compares two widely used methods for estimating energy requirements in critically ill patients: IC and basic predictive equations. EE—energy expenditure, IC—indirect calorimetry.

Figure 3

Genomics and metabolomics. The material used for genomics (DNA), transcriptomics (RNA), proteomics (proteins), and metabolomics (metabolites) are extracted from cells collected from an individual. These cells can be obtained from organs, tissues, endothelia, or the circulating blood. Their collection, either by biopsy or, more simply, from the peripheral blood, can provide a window into the omics of specific tissues, cells, or circulating elements.

Figure 4

The figure illustrates the complexity of nutritional care for critically ill patients in the ICU, highlighting the multidisciplinary and integrated nature of a medical intervention. The focus is on the critically ill patient, connected to multiple monitoring and life support systems, around whom many specialists (ICU medical team, support specialists) and various technical and decision-making factors revolve. Nutritional decision making in intensive care does not belong exclusively to a single specialist; rather, it results from collaboration among various fields within an organized framework, supported by technology and institutional regulations. The ultimate objective is to provide safe, efficient, and adapted nutrition to the critically ill patient.