Changes in Bile Acid Metabolism and Nutrient-Stimulated Hormone Responses After Malabsorptive Metabolic Surgery: RYGB Versus SADI-S

Background/Objectives: Bariatric–metabolic surgery (BMS) improves obesity through neuroendocrine mechanisms involving bile acids (BAs) and nutrient-stimulated gastrointestinal hormones. However, the underlying pathophysiology involved remains poorly understood. BAs are essential for the digestion and absorption of dietary fat and fat-soluble vitamins and act as nutrient-responsive signaling molecules, so their handling after malabsorptive procedures is relevant both to metabolic outcomes and to nutritional status.

Methods

We prospectively compared Roux-en-Y gastric bypass (RYGB) and single-anastomosis duodeno-ileal bypass with sleeve gastrectomy (SADI-S) in a single-center case-control study including 37 RYGB and 31 SADI-S patients with severe obesity and 19 non-obese controls. Before and one year after surgery, participants underwent a standardized mixed-meal test (nutrient challenge) with measurement of 14 individual BA fractions, insulin, GLP-1, ghrelin, FGF19, leptin, and adiponectin; bile acid malabsorption was assessed one year after surgery with the 75Se-SeHCAT test, and weight was followed for up to 5 years.