The Importance of the Microbiome in Bariatric Surgery: a Systematic Review.

Bariatric surgery results in sustained weight loss, improvement of metabolic and hormonal changes, and reduction of comorbidities in obese patients. However, beneficial effects of bariatric surgery are not solely explained by restriction and malabsorption induced by surgery itself. Changes in the microbiome might play a role in this mechanism. A systematic review was performed in which 21 studies were included. The microbiome was affected by surgery and profound changes occurred in the first year of follow-up. An increase in Bacteroides and Proteobacteria and a decrease in Firmicutes were observed postoperatively in most studies. These changes were associated with weight loss. Bariatric surgery induces profound changes in the microbiome. This may be related to the beneficial effect of bariatric surgery on comorbidities associated with obesity.