The effects of intravenous glutamine supplementation in critically ill patients: a systematic review and meta-analysis

Background: Studies evaluating intravenous (IV) glutamine supplementation in critically ill patients have shown inconsistent results. This study aimed to evaluate the effects of IV glutamine on mortality, infectious complications, length of stay, and duration of mechanical ventilation. Methods: A systematic search of Ovid Medline, Embase, the Cochrane Central Register of Controlled Trials, and KoreaMed was conducted from inception through October 2023 and updated in April 2025. Randomized controlled trials comparing IV glutamine supplementation with standard care in critically ill adults were included. Pooled estimates were calculated using random-effects models. Results: A total of 10 randomized trials involving 1,593 critically ill patients were included in the analysis. IV glutamine supplementation was not associated with reduced overall mortality (risk ratio [RR], 0.93; 95% CI, 0.77-1.13) or overall infection rates (RR, 0.86; 95% CI, 0.63-1.18). No mortality benefit was observed in either non-surgical or surgical/trauma subgroups. Glutamine supplementation was associated with reduced pneumonia incidence (RR, 0.65; 95% CI, 0.49-0.87) and shorter mechanical ventilation duration (mean difference, -0.97 days; 95% CI, -1.62 to -0.32); however, these findings were based on a limited number of small studies. Intensive care unit and hospital length of stay were longer in the glutamine group. Conclusions: IV glutamine supplementation was not associated with improved survival or overall infection rates in critically ill adults. Current evidence does not support routine IV glutamine supplementation in unselected critically ill patients.