Bacterial Endotoxin and Non-alcoholic Fatty Liver Disease in the General Population: a Prospective Cohort Study

Background: Patients with non-alcoholic steatohepatitis (NASH) have increased intestinal permeability and small intestine bacterial overgrowth.

Aims: To test the hypothesis that endotoxemia is associated with non-alcoholic fatty liver disease (NAFLD) in the general population, and to study dietary factors associated with endotoxemia.

Methods: Nine hundred and twenty adults were randomly selected from the government's census database and underwent proton-magnetic resonance spectroscopy to assess hepatic steatosis. Endotoxemia was assessed using the limulus amebocyte lysate, lipopolysaccharide-binding protein (LBP) and EndoCab immunoglobulin G (IgG) assays.

Results: Two hundred and sixty-three (29%) subjects had NAFLD. Subjects with NAFLD had slightly higher LBP (P < 0.001) and EndoCab IgG (P = 0.013) levels. EndoCab IgG remained an independent factor associated with intrahepatic triglycerides after adjusting for other metabolic factors. Among 565 subjects without NAFLD at baseline who had repeated assessment at a median interval of 47 months, 78 (13.8%) developed incident NAFLD and they also had higher LBP (P = 0.016). Moreover, LBP was associated with insulin resistance and dyslipidaemia, and modestly increased with the cytokeratin-18 fragment level but not liver stiffness measurement by transient elastography. Although total energy consumption and individual macronutrients were not associated with endotoxemia, current drinkers (mostly <140 g/week) had lower endotoxin, EndoCab IgG and fetuin-A levels than nondrinkers.

Conclusions: Endotoxin markers are associated with NAFLD in the general population, but do not have a major effect on NASH and fibrosis. People with modest alcohol consumption have lower serum endotoxin. This may partly explain the lower risk of NAFLD and NASH in modest drinkers in previous observational studies.