Feeding the injured brain: nutrients, dose, timing, and monitoring

Nutrition is a key component of the management of neurocritically ill patients. The healthy brain accounts for up to 25% of total resting energy expenditure (REE), and after injury the brain faces inflammation, altered glucose metabolism, and catabolic stress. This review outlines the evolving science and current practice of nutrition in neurocritical illness, emphasizing pathophysiology, metabolic phases, and individualized strategies. Enteral nutrition remains the preferred route, with early, low-dose initiation within 24-48 h generally recommended. Feeding intolerance, aspiration risk, and altered gastrointestinal motility are common barriers. Parenteral nutrition may be warranted when enteral nutrition is contraindicated or insufficient; however, early initiation of target feeding, independent of the enteral or parenteral route of administration, has shown harm in general ICU populations and remains underexplored in neurocritically ill patients. The role of timing to start feeding, energy and protein dosing, micronutrient supplementation, and metabolic monitoring via indirect calorimetry is discussed, with recent trials questioning traditional targets. Emerging concepts include the ketogenic diet, exogenous lactate, and immunonutrition, all of which aim to optimize recovery and reduce secondary brain injury. Despite promising mechanistic rationale, robust neurocritical-specific data are lacking. Personalized nutrition based on metabolic phenotyping and real-time monitoring to optimize neurocritical nutrition requires further validation. Ultimately, nutritional care in neurocritical settings might benefit from a multidisciplinary integrated approach. Rather than supportive care alone, nutrition could be viewed as a modifiable therapeutic intervention with the potential to influence neurological recovery and long-term outcomes.