What Role Does Bariatric Surgery Play in Altering the Gut Microbiome?

The growing prevalence of obesity worldwide has ushered in a host of metabolic diseases, including diabetes, nonalcoholic fatty liver disease, and ischemic heart disease.¹ This rise in obesity has led researchers to study possible modifiable factors, including the gut microbiome, to turn back the tide.

How Modern Life Alters the Gut Microbiome

Lifestyle changes in diet and sleep patterns may be affecting patients with morbid obesity (body mass index >35-40 kg/m²).² As such, researchers are attempting to characterize how the modern human lifestyle affects the gut microbiome.¹ Evidence shows that circadian disturbances caused by issues such as jet lag or shift work adversely alter the gut microbiome and set the stage for obesity and other metabolic diseases.¹

In patients with severe obesity, the gut microbiome remains altered even after surgical weight loss.² Research shows that obesity is linked to a less robust microbiome for maintaining health years after bariatric surgery. Low bacterial richness may usher in inflammation, altered adipocyte size, and insulin resistance.²

Return to an Obesogenic Microbiome After Surgery

To determine the extent of microbiome alterations after bariatric surgery, Nan Shen, MSc, a biomedical engineer at the Icahn School of Medicine at Mount Sinai in New York City, and colleagues followed 26 patients, 8 of whom had type 2 diabetes, in New York City and Barcelona, Spain. Follow-up continued for 1 year after bariatric surgery. At 3 and 6 months after surgery, patients who had undergone Roux-en-Y gastric bypass or sleeve gastrectomy showed rapid changes in microbiome diversities.³

At 12 months after surgery, however, patients’ microbiomes nearly resembled their preoperative states.³ The researchers reported that 15 bacterial pathways related to metabolism improved after surgery, but 12 had partial regression to their baseline status 1 year after surgery, regardless of the type of procedure, location, or diabetes status.³ Researchers said that the return to presurgery microbiota levels may presage poor metabolic health.³

“Microbiome research is in its infancy,” said coauthor Blandine Laferrère, MD, PhD, professor of medicine and co-director of the Diabetes Research Center Translational Biomarkers Analytical Core at Columbia University College of Physicians and Surgeons in New York City. “Although it is possible that targeting the microbiome could be part of the future panel to treat obesity and metabolic disorders, we are not there yet. The focus should be on a healthy diet. The contribution of diet composition to the microbiome signature, an element that could not be assessed in our study, is likely to be extremely important. Future research needs to uncover the mechanisms by which diet composition alters whole metabolism through changes in the gut microbiome.”

This article originally appeared on Endocrinology Advisor