Effects of probiotic, prebiotic or synbiotic supplementation after Roux-en-Y gastric bypass: a systematic review with meta-analysis

The Roux-en-Y gastric bypass (RGYB) is a type of bariatric surgery that, despite its benefits, is associated with multiple gastrointestinal and nutritional complications, so using the microbiota as a therapeutic target can enhance its benefits and reduce the risk of complications. Therefore, this study aimed to evaluate the effects of probiotic, prebiotic or synbiotic supplements in patients with morbid obesity undergoing bariatric Roux-en-Y surgery. A systematic literature review was conducted using PubMed, Scopus, Web of Science, Ovid-Medline, Cochrane library and Embase databases through January 2022. The search strategy identified 766 articles, of which, after selection process, four randomized clinical trial (RCTs) studies were included. Twelve percent of patients were men, and the mean age ranged between 32.0 and 48.6 years. Three trials included probiotic supplementation, one included two types of interventions (prebiotic and symbiotic supplementation). Three were conducted in Brazil, one in United States. Regarding the percentage of excess weight loss (%EWL), with very low certainty, in two RCTs that including 144 participants, probiotic supplementation did not reduce significantly %EWL compared to placebo ([MD]: -2.38; 95% CI: -6.11, 1.35; I2 = 0%). Probiotic supplementation reduced discomfort measured by Gastric Symptom Rating Scale ([MD]: -0.50; 95% CI: -0.63, -0.37), reduce triglycerides blood levels ([MD]: -0.21.8 mg/dl; 95% CI: -24.1, -19.5) and increase B12 vitamin ([MD]: 18.2 pmol/L; 95% CI: 14.2, 22.2) compared to placebo.