Bilio-enteric flow and plasma concentrations of bile acids after gastric bypass and sleeve gastrectomy

Bile acids in plasma are elevated after bariatric surgery and may contribute to metabolic improvements, but underlying changes in bile flow are poorly understood. We assessed bilio-enteric flow of bile and plasma bile concentrations in individuals with Roux-en-Y gastric bypass (RYGB) or sleeve gastrectomy (SG) surgery compared with matched non-surgical controls (CON).

Fifteen RYGB, 10 SG and 15 CON underwent ⁹⁹Tc-mebrofenin cholescintigraphy combined with intake of a high-fat ¹¹¹In-DTPA-labelled meal and frequent blood sampling. A ⁷⁵Se-HCAT test was used to assess bile acid retention.

After RYGB, gallbladder filling was decreased (p = 0.045 versus CON), basal flow of bile into the small intestine increased (p = 0.005), bile acid retention augmented (p = 0.021) and basal bile acid plasma concentrations elevated (p = 0.009). During the meal, foods passed unimpeded through the gastric pouch resulting in almost instant postprandial mixing of bile and foods, but the postprandial rise in plasma bile acids was brief and associated with decreased overall release of fibroblast growth factor-19 (FGF-19) compared with CON (p = 0.033). After SG, bile flow and retention were largely unaltered (p > 0.05 versus CON), but gastric emptying was accelerated (p < 0.001) causing earlier mixture of bile and foods also in this group. Neither basal nor postprandial bile acid concentrations differed between SG and CON.

Bilio-enteric bile flow is markedly altered after RYGB resulting in changes in plasma concentrations of bile acids and FGF-19, whereas bile flow and plasma concentrations are largely unaltered after SG.