Medical Research: An alternative weight-loss surgery

Diverting bile flow to the final section of the small intestine has comparable anti-obesity effects in mice to gastric bypass surgery, a study published in Nature Communications reports this week.

Weight-loss surgery, such as Roux-en-Y gastric bypass surgery (RYGB) and vertical sleeve gastrectomy, remove parts of the stomach, or connect a smaller stomach pouch directly to the small intestine. These surgical procedures are among the most effective interventions for lasting weight loss and reversal of diabetic symptoms in humans. It was shown previously that bile acids mediate some of the beneficial metabolic effects of gastric bypass surgery.

Naji Abumrad and colleagues connected the gallbladder of obese mice to various parts of the small intestine and compared the metabolic benefits directly with RYGB in mice, over a period of up to eight weeks. They found that diverting bile acid flow to the final section of the small intestine (ileum) was sufficient to cause similar anti-obesity effects to the more complicated traditional surgical approach. The authors suggest that reduced fat absorption in the small intestine and changes to gut microbiota are partly responsible for these effects.

Although bile diversion is less invasive and less technically demanding than RYGB, the authors caution that the long-term safety and efficacy of this procedure is yet to be determined. In addition, the approach may not work for diabetic or obese individuals, who had their gallbladders removed owing to gall stone problems, and the extent to which the procedure is reversible is currently unclear.

doi: 10.1038/ncomms8715

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