Immunonutrition in minimally invasive major abdominal surgery: A systematic review and meta-analysis of randomized clinical trials.

BACKGROUND & AIMS: Immunonutrition is recommended in major abdominal surgery. Evidence is sparse on its effect in minimally invasive procedures. This study aimed to assess its effect on postoperative outcomes in minimally invasive major abdominal surgery.

METHODS

CENTRAL, PubMed, EMBASE, and Web of Science were systematically searched (last update: May 28, 2025). All randomized clinical trials (RCTs) investigating immunonutrition versus standard nutrition in patients undergoing minimally invasive major abdominal surgery were included. Mortality, overall and infectious complications, and length of hospital stay (LOS) were analyzed using odds ratios (OR) or mean differences (MD) in a random-effects model. Risk of bias (Cochrane 2.0) and certainty of evidence (GRADE) were assessed.

RESULTS

Eleven RCTs comprising 890 patients were included. The overall risk of bias was high in eight RCTs, with some concerns in two and low in one. Immunonutrition may not reduce mortality (OR 1.01, 95 %-CI: 0.2 to 5.08, p = 0.99, I2 = 0 %, GRADE: low). It may have little to no effect on overall (OR 1.25, 95 %-CI: 0.65 to 2.4, p = 0.5, I2 = 60 %, GRADE: very low) or infectious complications (OR 0.75, 95 %-CI: 0.44 to 1.28, p = 0.3, I2 = 32 %, GRADE: very low), and LOS (MD +0.03 days, 95 %-CI: -0.65 to +0.71, p = 0.93, I2 = 47 %, GRADE: very low) but the evidence is very uncertain. These findings persisted after excluding high-risk-of-bias studies (8/11). There was not enough data to analyze higher risk subgroups such as malnourished patients.

CONCLUSION

The effects of immunonutrition observed in open surgery are not present in minimally invasive major abdominal surgery, making its routine use in this setting unjustified. High-quality RCTs in nutritionally at-risk patients are warranted.