Friday, 7 July 2017

Shift in gut microbes after surgery


Obesity is linked with the composition of microbes in the human gut. In new research, bacterial composition in the gut, as well as accompanying metabolites are shown to undergo a profound and permanent shift, with microbial diversity significantly increasing following gastric bypass surgery.

A new study compares the two most common surgical therapies for obesity, known as Roux-en-Y gastric bypass (RYGB), and laparoscopic adjustable gastric banding (LAGB). The results demonstrate that RYGB -- the more aggressive of the two surgeries -- produces profound changes in the composition of microbial communities in the gut, with the resulting gut flora distinct from both obese and normal weight patients. The results are likely due to the dramatic reorganization of the gut caused by RYGB surgery, which increases microbial diversity. The new research paves the way for new diagnostics and therapies for obesity.

The gamut of adverse health effects associated with obesity is broad, including such devastating illnesses as type 2 diabetes, coronary artery disease, stroke and certain forms of cancer. Patients often suffer a loss of mobility, social isolation and inability to work. Currently, bariatric surgery is the most effective treatment for morbid obesity, in terms of significant and sustained weight loss.

The study sought to explore long-term changes in the gut in patients who had undergone either of the two surgeries at least 9 months prior, comparing them with normal weight and pre-bariatric obese patients. While the reasons for the sharp disparity of results between RYGB and gastric banding are not entirely clear, the results indicate that simply reducing the size of the stomach through gastric banding is not sufficient to induce the large changes in microbial communities observed for the RYGB group.

See:

Zehra Esra Ilhan, John K DiBaise, Nancy G Isern, David W Hoyt, Andrew K Marcus, Dae-Wook Kang, Michael D Crowell, Bruce E Rittmann, Rosa Krajmalnik-Brown. Distinctive microbiomes and metabolites linked with weight loss after gastric bypass, but not gastric banding. The ISME Journal, 2017; DOI: 10.1038/ismej.2017.71

Posted by Dr. Tim Sandle