Success of Vertical Sleeve Gastrectomy Linked to Gut Metabolism

Changes in bile acids are the key to weight-loss success and improvement in diabetes following vertical sleeve gastrectomy (VSG).

Researchers at the University of Cincinnati (UC; OH, USA), the University of Gothenburg (Sweden), and Cincinnati Children's Hospital Medical Center (OH, USA) conducted a study to examine the results of VSG surgery applied to mice with diet-induced obesity and targeted genetic disruption of the nuclear receptor farsenoid-X receptor (FXR). The results of the study showed that the therapeutic value of VSG does not result from mechanical restriction imposed by a smaller stomach, but rather increased circulating bile acids and associated changes to gut microbial communities.

The results point to bile acids and FXR signaling as an important molecular underpinning for the beneficial effects of VSG weight-loss surgery; moreover, in the absence of FXR, the ability of VSG to reduce body weight and improve glucose tolerance was substantially reduced. And because bile acids and FXR receptors interact with gut microbial communities, the researchers also looked at gut bacteria after VSG, and found that the surgery caused in changes in the gut flora. The study was publishing early online on March 26, 2014, in Nature.

“Importantly, we observed changes in several key bacterial groups that have been previously linked to the risk of Type 2 diabetes, and these changes were related to FXR and bile acids,” said lead author Prof. Karen Ryan, PhD, of the department of endocrinology, diabetes, and metabolism at UC.

“Conventional thought is when you make the stomach smaller, patients lose more weight because they have less room to put more food and, therefore, eat fewer calories,” added co-principal author Prof. Randy Seeley, PhD, director of the Cincinnati Diabetes and Obesity Center. “But as it turns out, the reason why the surgery works is that you are changing the bile acids.”

VSG is the surgical removal of a large portion of the stomach along the greater curvature, reducing it to about 25% of its original size. The procedure involves a longitudinal resection of the stomach starting from the antrum at the point 5–6 cm from the pylorus and finishing at the fundus close to the cardia; the remaining gastric sleeve is calibrated with a bougie, with the ideal approximate remaining size of the stomach after the procedure at about 150 mL. VSG is the fastest growing weight loss surgery option in North America and Asia.

Related Links:
University of Cincinnati
University of Gothenburg
Cincinnati Children's Hospital Medical Center