# Gastrointestinal Permeability After Bariatric Surgery: A Systematic Review

## TL;DR

This study reviews how bariatric surgery affects gut permeability, finding mixed results depending on the type of surgery and body location.

## Contribution

The paper provides a systematic review of gastrointestinal permeability changes after bariatric surgery, highlighting conflicting evidence and key influencing factors.

## Key findings

- Gastroduodenal permeability decreased after sleeve gastrectomy.
- Small intestinal permeability increased after biliopancreatic diversion.
- Colonic permeability increased six months post-sleeve gastrectomy.

## Abstract

Gastrointestinal permeability refers to the movement of substances across the gut wall. This is mediated by endotoxemia (bacterial products entering the systemic circulation), and is associated with metabolic disease. The effect of bariatric surgery on permeability remains uncertain; the associated dietary, metabolic and weight changes are suggested to influence, or trigger, altered permeability. The primary aim of this study is to synthesize evidence and analyze the effect of bariatric surgery on permeability. A systematic review was performed, searching MEDLINE, EMBASE, and Scopus until February 2023, using MESH terms “intestinal permeability”, “bariatric”, for studies reporting in vivo assessment of permeability.

Three cohort studies and two case series were identified (n=96). Data was heterogeneous; methodology and controls preclude meta-analysis. Gastroduodenal permeability reduced post-sleeve gastrectomy (SG). Two studies showed an increase in small intestinal permeability after biliopancreatic diversion. Two studies revealed a decrease in post-Roux-en-Y gastric bypass. One study identified increased colonic permeability six months post-SG. Evidence regarding permeability change after bariatric surgery is conflicting, notably for the small intestine. Impaired colonic permeability post-SG raises concerns regarding colonic protein fermentation and harmful dietary sequelae. There are multiple interacting variables confounding gastrointestinal permeability change; procedure type, altered microbiota and metabolic response to surgery. Further understanding of this important aspect of obesity is required, both before and after bariatric surgery.