Review calls for phase- and phenotype-informed protein research in critical care

Protein targets for critically ill patients have traditionally been based on body weight, with higher delivery intended to limit muscle loss and catabolism. This narrative review appraises randomised trials, systematic reviews and meta-analyses, alongside selected mechanistic and non-randomised evidence; it does not report a new patient cohort or trial. The authors note that recent large randomised trials comparing higher with lower protein delivery have not shown benefit on their primary patient-centred outcomes. Renal subgroup findings raise safety concerns but do not establish that patients without acute kidney injury benefit from higher protein exposure.

The review argues that protein needs and capacity to process protein may change across metabolic stress and recovery, and that patients of similar weight can differ in muscle mass and adiposity. CT, muscle ultrasound and bioelectrical impedance may help describe body composition, but their limitations and lack of validation for determining individual protein requirements are emphasised. The authors propose future phase-specific and phenotype-enriched trials, with outcomes including muscle health, function, independence and quality of life, while accounting for death.

The proposed phase-, phenotype- and response-informed approach is biologically plausible but remains unvalidated; the review does not provide a dosing algorithm or evidence to support changing current practice. The article reports no specific funding. Several authors disclose research support, grants, consultancy fees or honoraria from nutrition and healthcare companies, all described as outside the submitted work.