Current concepts on feeding the critically ill patient: a narrative review

Nutritional therapy is a key component of critical care management, yet optimal strategies remain debated due to the heterogeneity of ICU patients, dynamic metabolic alterations, and the profound influence of inflammation on nutrient utilisation. Evidence from recent trials has challenged traditional one-size-fits-all approaches, emphasising the need for individualised, phase-specific nutrition throughout the continuum of critical illness and recovery. This manuscript summarises current concepts and emerging evidence in nutrition therapy presented at the 39th Annual Conference of the German Society for Nutritional Medicine (DGEM). Experts reviewed and critically discussed inflammation-driven metabolic changes, personalised energy and protein prescriptions, micronutrient management, macronutrient adaptation, ketogenic strategies in neurocritical care and sepsis, and nutritional considerations in post-ICU syndrome and outpatient recovery. This overview does not claim to be exhaustive; interpretations of individual study results partly reflect the views of the experts. Together with the inclusion of newer therapeutic approaches, this is intended to stimulate discussion and, at the same time, provide a basis for further studies.

Inflammation and high disease severity strongly influence nutritional responsiveness, with highly inflamed patients demonstrating reduced benefit and heightened risk of overfeeding. Personalised strategies, including indirect calorimetry, fat-free mass-based protein dosing, and metabolic biomarkers such as the urea-creatinine ratio, offer a rational framework for tailoring therapy. Micronutrient deficiencies are common due to redistribution, pre-existing deficits, and extracorporeal losses, necessitating structured assessment and supplementation. Macronutrient delivery should be progressively escalated and regarded as a pharmacologic intervention aligned with disease phase and organ function. Early standardised ketogenic diet protocols show feasibility and potential clinical benefit in refractory status epilepticus and sepsis. Post-ICU and outpatient phases remain nutritionally vulnerable, with persistent catabolism and underfeeding common; structured, multidisciplinary rehabilitation and transitional nutrition programs may improve long-term outcomes.

Future personalised nutrition strategies may rely on metabolic phenotyping and biomarker-informed stratification rather than uniform protein, energy and micronutrient targets for all ICU patients. Integrating individualised energy and protein prescription, targeted micronutrient management, emerging metabolic therapies, and coordinated post-ICU rehabilitation may optimise recovery and functional outcomes. Robust clinical trials are needed to confirm the impact of these personalised strategies on long-term patient-centred endpoints.