Effects of glutamine on plasma protein and inflammation in postoperative patients with colorectal cancer: a meta-analysis of randomized controlled trials

OBJECTIVE: To evaluate the effects of glutamine on the plasma protein and inflammatory responses in colorectal cancer (CRC) patients following radical surgery. METHODS: We thoroughly retrieved online databases (EMBASE, MEDLINE, PubMed, and others) and selected the randomized controlled trials (RCTs) with glutamine vs. conventional nutrition or blank treatment up until March 2023. The plasma protein associated markers indicators (consisting of albumin (ALB), prealbumin (PA), nitrogen balance (NB), total protein (TP)), inflammatory indicators (including TNF-α, CRP, infectious complications (ICs)), and matching 95% confidence intervals (CIs) were evaluated utilizing the pooled analysis. Subsequently, meta-regression analysis, contour-enhanced funnel plot, Egger’s test, and sensitivity analysis were carried out. RESULTS: We discovered 26 RCTs, included an aggregate of 1678 patients, out of which 844 were classified into the glutamine group whereas 834 were classified into the control group. The findings recorded from pooled analysis illustrated that glutamine substantially enhanced the plasma protein markers (ALB [SMD([random-effect]) = 0.79, 95% CI: 0.55 to 1.03, I(2) = 79.4%], PA [SMD([random-effect]) = 0.94, 95% CI: 0.69 to 1.20, I(2) = 75.1%], NB [SMD([random-effect]) = 1.11, 95% CI: 0.46 to 1.75, I(2) = 86.9%). However, the content of TP was subjected to comparison across the 2 groups, and no statistical significance was found (SMD([random-effect]) = − 0.02, 95% CI: − 0.60 to 0.57, P = 0.959, I(2) = 89.7%). Meanwhile, the inflammatory indicators (including TNF-α [SMD([random-effect]) = − 1.86, 95% CI: − 2.21 to − 1.59, I(2) = 56.7%], CRP [SMD([random-effect]) = − 1.94, 95% CI: − 2.41 to − 1.48, I(2) = 79.9%], ICs [RR([fixed-effect]) = 0.31, 95% CI: 0.21 to 0.46, I(2) = 0.00%]) were decreased significantly followed by the treatment of glutamine. CONCLUSIONS: The current study’s findings illustrated that glutamine was an effective pharmaco-nutrient agent in treating CRC patients following a radical surgical operation. PROSPERO registration number: CRD42021243327. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00384-023-04504-8.