Increased intestinal permeability and dysbiosis have been causally associated with NAFLD and NASH progression. However, to date, there are no systematic studies, on the effect of bariatric-metabolic surgery on intestinal permeability and dysbiosis in the context of NAFLD development.

Morbid obesity is associated with non-alcoholic fatty liver disease (NAFLD) in 80-90% of patients, and non-alcoholic steatohepatitis (NASH) occurs in up to 60% of patients. If left untreated, the disease can progress to liver fibrosis, cirrhosis, or hepatocellular carcinoma. Weight loss of >10% of body weight is the most effective treatment for NAFLD, and bariatric metabolic surgery plays an effective role in achieving long-term weight loss. About 80% of patients achieve improvement or reversal of NAFLD after bariatric-metabolic surgery. However, clinical and histological progression of liver disease may occur in about 20% of patients, despite weight the loss. Increased intestinal permeability and dysbiosis have been causally associated with NAFLD and NASH progression. However, to date, there are no systematic studies, on intestinal permeability and dysbiosis after bariatric-metabolic surgery.

Research questions

• To investigate the changes in intestinal permeability after bariatric-metabolic surgery.
• To investigate the differences in intestinal permeability at the time of surgery and 1 year after surgery between patients with liver fibrosis grades F≤1 and F≥2 (low-grade fibrosis vs advanced fibrosis).
• To investigate differences between patients with and without liver fibrosis progression using parameters for metabolic endotoxemia, intestinal permeability, and dysbiosis.

Inclusion Criteria:

• Patients with morbid obesity undergoing bariatric metabolic surgery according to the IFSO criteria,
• Willingness to attend all follow-up visits
• Written consent

Exclusion Criteria:

• other liver disease than NAFLD
• presence of IBD, acute pancreatitis, amyotrophic lateral sclerosis, pregnancy

In our patients about 80% have NAFLD, about 50-60% are diagnosed with NASH. Furthermore, we know from our obese patient cohort, that 26% are diagnosed with fibrosis grade 2 or higher. Only patients that are scheduled for weight loss surgery will be enrolled in the study.