Impact of Probiotic/Synbiotic Supplementation on Post-Bariatric Surgery Anthropometric and Cardiometabolic Outcomes: An Updated Systematic Review and Meta-Analysis of Randomized Controlled Trials.

BACKGROUND/OBJECTIVES: Bariatric surgery improves weight and metabolic health in individuals with severe obesity; however, challenges like gut dysbiosis and nutrient deficiencies persist postoperatively. Probiotic supplementation may enhance recovery by modulating gut microbiota. This updated meta-analysis aimed to assess the effects of probiotics/synbiotics on metabolic, anthropometric, and nutritional outcomes after bariatric surgery.

METHODS

A systematic review and meta-analysis of randomized controlled trials (RCTs) was conducted using PubMed, SCOPUS, Web of Science, and CENTRAL through December 2024. Studies comparing probiotics/synbiotics (which contain both probiotics and prebiotics) versus a placebo in adults post-bariatric surgery were included. Meta-analyses were conducted, with subgroup analyses by surgery type, the timing of the intervention, and probiotic formulation (PROSPERO ID: CRD420251019199).

RESULTS

Thirteen RCTs involving 809 patients were included in the analysis. Probiotic use significantly reduced BMI (MD = 0.67, 95% CI: 0.33 to 1.00), HbA1c (MD = -0.19%, 95% CI: -0.36 to -0.01), triglycerides (MD = -16.56 mg/dL), and AST levels (MD = -3.68 U/L), while increasing ALP (MD = 8.12 U/L) and vitamin D (MD = 13.68 pg/mL). Ferritin levels were significantly lower (MD = -18.89 µg/L) in the probiotic group. A subgroup analysis showed enhanced benefits in patients undergoing mini-gastric bypass, with perioperative or synbiotic interventions specifically improving triglycerides, total cholesterol, and HbA1c.

CONCLUSIONS

Probiotics may offer modest but significant improvements in BMI, glycemic control, lipid profile, liver enzymes, and vitamin D levels after bariatric surgery. These findings support the potential role of probiotics/synbiotics as an adjunct therapy, though further large-scale trials are warranted to confirm long-term benefits.