Effect of glutamine supplementation on inflammatory markers in critically ill patients supported with enteral or parenteral feeding

Background: Glutamine plays an important role in acute catabolic conditions in critically ill patients. This meta-analysis aimed to investigate the effect of glutamine supplementation on inflammatory markers in critically ill patients supported with enteral feeding (EN) or parenteral feeding (PN). Methods: PubMed, Web of Science, Scopus, and Embase were explored to identify the studies investigating the effect of glutamine on serum inflammatory markers in intensive care unit patients. All randomized clinical trials that assessed the effect of glutamine supplementation on "inflammatory markers" in EN or PN were included in the study. Because a small number of studies were included, SE was adjusted for overall effect size by using the Knapp-Hartung method. Results: In this study, 2728 eligible studies were initially included, and 10 eligible case-control studies were finally enrolled for further investigations. There was a statistical reduction between preintervention and postintervention CRP levels (standardized mean difference [SMD] = -0.38 mg/L; 95% CI, -0.72 to -0.03). No significant association was found between L-glutamine supplementation in the EN/PN and interleukin 6 (IL-6) (SMD = -0.58 pg/ml; 95% CI, -2.15 to 0.99) and tumor necrosis factor alpha (TNF-alpha) (SMD = 2.69 pg/ml; 95% CI, -9.66 to 15.03) compared with the control group. Conclusions: This study identified that glutamine supplementation might have an important effect on CRP in acute conditions and no significant effect on IL-6 and TNF-alpha in acute conditions.