Zonulin level, a marker of intestinal permeability, is increased in association with liver enzymes in young adolescents.

Background: Zonulin is acknowledged as the only physiological mediator established to reversibly regulate intestinal permeability through modulation of intercellular tight junctions. We aimed to determine whether there are differences in zonulin levels between 74 subjects with overweight or obesity and 76 with normal-weight and to assess correlations of circulating zonulin levels with anthropometric measures and obesity-related biomarkers.

Methods: We assessed anthropometric and laboratory measures, including body mass index (BMI) z-score, blood pressure, liver enzymes, lipid profiles, and insulin resistance. Serum zonulin levels were measured using an enzyme-linked immunosorbent assay.

Results: The mean age of the participants was 12.8 ± 1.5 years. Circulating serum zonulin levels were significantly increased in subjects with overweight/obesity compared with those of normal-weight (P = 0.03). Zonulin levels were significantly and positively associated with BMI z-score, alanine aminotransferase levels, triglyceride, fasting insulin, and insulin resistance as indicated by the homeostatic model assessment of insulin resistance (HOMA-IR) (all P < 0.05). In multivariate linear regression analysis, alanine aminotransferase was significantly and positively associated with circulating zonulin levels in adolescents with overweight or obesity (P < 0.01) after controlling for the effect of potential confounding factors. BMI z-score tended to be positively associated with serum zonulin levels in this subgroup analysis (P = 0.06).

Conclusions: Serum zonulin is a biomarker associated with hepatic metabolic disturbances in young adolescents with overweight or obesity. The positive relationship suggests a potentially relevant pathophysiological mechanism linking zonulin to hepatic metabolism in this age group of young adolescents with overweight or obesity.