Effect of Glutamine Dipeptide Supplementation on Primary Outcomes for Elective Major Surgery: Systematic Review and Meta-Analysis

To evaluate if glutamine (GLN) supplementation may affect primary outcomes in patients undergoing major elective abdominal operations, we performed a systematic literature review of randomized clinical trials (RCTs) published from 1983 to 2013 and comparing intravenous glutamine dipeptide supplementation to no supplementation in elective surgical abdominal procedures. A meta-analysis for each outcome (overall and infectious morbidity and length of stay) of interest was carried out. The effect size was estimated by the risk ratio (RR) or by the weighted mean difference (WMD). Nineteen RCTs were identified with a total of 1243 patients (640 receiving GLN and 603 controls). In general, the studies were underpowered and of medium or low quality. GLN supplementation did not affect overall morbidity (RR = 0.84, 95% CI 0.51 to 1.36; p = 0.473) and infectious morbidity (RR = 0.64; 95% CI = 0.38 to 1.07; p = 0.087). Patients treated with glutamine had a significant reduction in length of hospital stay (WMD = -2.67; 95% CI = -3.83 to -1.50; p < 0.0001). In conclusion, GLN supplementation appears to reduce hospital stay without affecting the rate of complications. The positive effect of GLN on time of hospitalization is difficult to interpret due to the lack of significant effects on surgery-related morbidity.