Increased glycine-amidated hyocholic acid correlates to improved early weight loss after sleeve gastrectomy

Abstract

Background: Bile acids (BAs) are post-prandial hormones that play an important role in glucose and lipid homeostasis as well as energy expenditure. Total and glycine-amidated BAs increase after sleeve gastrectomy (SG) and correlate to improved metabolic disease. No specific bile acid subtype has been shown conclusively to mediate the weight loss effect. Therefore, the objective of this study was to prospectively evaluate the comprehensive changes in meal-stimulated BAs after SG and determine if a specific change in the BA profile correlates to the early weight loss response.

Methods: Patients were prospectively enrolled at the University of Nebraska Medical Center who were undergoing a SG for treatment of morbid obesity. Primary and secondary plasma bile acids and their amidated (glycine, G-, or taurine, T-) subtypes were measured at fasting, 30 and 60 min after a liquid meal performed pre-op, and at 6 and 12 weeks post-op. Area under the curve (AUC) was calculated for the hour meal test for each bile acid subtype. BAs that were significantly increased post-op were correlated to body mass index (BMI) loss.

Results: Total BA AUC was significantly increased at 6 (p < 0.01) and 12 weeks post-op (p < 0.01) compared to pre-operative values. The increase in total BA AUC was due to a statistically significant increase in G-BAs. Nine different BA AUC subtypes were significantly increased at both 6 and 12 weeks post-op. Increased total and G-chenodeoxycholic acid AUC was significantly correlated to the 6 week BMI loss (p = 0.03). Increased G-hyocholic acid was significantly correlated to increased weight loss at both 6 (p = 0.05) and 12 weeks (p = 0.006).

Conclusions: SG induced an early and persistent post-prandial surge in multiple bile acid subtypes. Increased G-hyocholic consistently correlated with greater early BMI loss. This study provides evidence for a role of BAs in the surgical weight loss response after SG.

Keywords: Bile acids; Chenodeoxycholic acid; Deoxycholic acid; Hyocholic acid; Sleeve gastrectomy; Weight loss.

Fig. 1

The change in the total fasting bile acid (BA) concentration after sleeve gastrectomy. The total BA is the sum of unamidated and glycine and taurine-amidated subtypes. Data presented as mean ± standard deviation (n = 28). Asterisk denotes statistical significance at week 6 and number sign at week 12 with p<0.05 compared to pre-op

Fig. 2

The change in the total bile acid (BA) area under the curve (AUC) from a liquid meal test measured at 0, 30, and 60 min. The total BA AUC is the sum of unamidated and glycine and taurine-amidated subtypes. Data presented as mean ± standard deviation (n = 28). Asterisk denotes statistical significance at week 6 and number sign at week 12 with p<0.05 compared to pre-op

Fig. 3

The positive correlation between glycine-amidated HCA (hyocholic acid) area under the curve (AUC) from a liquid test meal and BMI loss at 12 weeks after sleeve gastrectomy