Bariatric surgery may help gut microbiome recover, but not fully

Last Updated: 2018-07-04

By Anne Harding

NEW YORK (Reuters Health) - Microbial gene richness (MGR) improves in severely obese patients after bariatric surgery (BS), but remains low for years after the procedure, according to new research.

"The lack of full rescue post-BS calls for additional strategies to improve the gut microbiota ecosystem and microbiome-host interactions in severe obesity," Dr. Karine Clement of Sorbonne University in Paris and colleagues conclude in Gut, online June 13.

Gut dysbiosis occurs in overweight and moderately obese patients, but little research has been done on gut microbiota in severe and morbid obesity, Dr. Clement and her team note.

"BS represents a good model to understand the intestinal contribution to health improvements by comparing adjustable gastric banding (AGB), a procedure solely inducing caloric restriction due to gastric volume reduction . . ., and Roux-en-Y gastric bypass (RYGB), which by contrast drastically rearranges the digestive tract architecture and adds intestinal malabsorption to food intake reduction," they add.

The researchers looked at gut microbiota before and after BS in 61 severely obese women, including 20 treated with AGB and 41 who received RYGB. Before surgery, three-quarters had low gene count (LGC), which correlated with increased fat mass at the trunk and comorbidities including hypertension and type 2 diabetes (T2D).

LGC was negatively correlated with triglycerides, uricemia and markers of systemic inflammation including fibrinogen and neutrophil count. MGR was inversely correlated with adverse body composition, and was lower in patients with T2D. MGR was lower in patients with high blood pressure, with trends toward associations with other metabolic syndrome components.

The researchers looked at microbial recovery in 24 patients at one, three and 12 months after BS. The 14 RYGB patients in the group had greater improvements in body composition and metabolic and inflammatory profiles compared to the 10 AGB patients at one year. However, recovery of MGR was similar for the two groups, and did not improve further after one year.

"It remains unknown whether this low MGR is a cause or consequence of obesity and of its duration, but it represents a good biomarker of gut microbiota alteration, eventually useful for patient stratification," Dr. Clement and her team write.

"In their concluding remarks, the authors suggest interventions such as fecal microbial transplantation," Dr. Manimozhiyan Arumugam, who leads a group studying the gut microbiome and health at the University of Copenhagen, Denmark, told Reuters Health by email. "I would also add dietary approaches, for example by switching to a healthy diverse fibre-rich diet that can support a diverse microbiota. This may not be easy for patients who underwent bariatric surgery, as their appetite and preferences could be different after surgery. So expert dietary consultation and advice could make a big difference in effectively modifying their diets."

He added: "We need to understand whether low microbial richness is a cause or a consequence of obesity. A clear answer to this question will have a large impact in the ways we can design therapies in the future."

Dr. Clement was not available for an interview by press time.

SOURCE: https://bit.ly/2yN7yRl

Gut 2018.