Overweight and obesity and their association with intestinal permeability, usual dietary intake, and serum retinol...

Obesity may affect gut health by altering the intestinal barrier function. Excess body fat disrupts plasma levels of fat-soluble vitamins, such as vitamin A, which is crucial for maintaining intestinal permeability. Thus, excess body fat and low retinol concentrations may contribute to intestinal barrier dysfunction in individuals, a condition that remains poorly understood in the context of overweight and obesity. This study aimed to evaluate the associations of overweight and obesity with intestinal barrier permeability, usual dietary intake, and serum retinol concentrations.

This cross-sectional study included 89 individuals aged >18 years, with data collected from October 2019 to March 2023. Self-reported disease status, anthropometric measures (weight, height, waist, and hip circumferences), biochemical measures (lipid profile, glycemic status, serum retinol, and α-tocopherol levels), intestinal permeability, and dietary usual intake (using two 24-h recalls and the MSM method) were collected.

individuals with overweight or obesity exhibited lower intestinal permeability measured by the Lactulose/Mannitol test (0.035 [0.016-0.064] vs 0.060 [0.028-0.092]; P = 0.036). Usual dietary intake, including vitamin A consumption, did not differ between groups (391.49 [291.49-572.98] μg vs. 368.21 [190.42-557.06] μg; P = 0.545). Despite similar intakes, individuals with overweight or obesity had significantly higher serum retinol concentrations (1.51 vs. 1.00 μmol/L; p = 0.013), suggesting that differences in vitamin A status are more likely driven by metabolic alterations than by dietary intake. BMI correlated positively with anthropometric adiposity markers (waist: ρ = 0.864; hip: ρ = 0.854; WHR: ρ = 0.391; all p < 0.001) and metabolic parameters, including triglycerides (ρ = 0.479; p < 0.001), insulin (ρ = 0.749; p < 0.001), HOMA-IR (ρ = 0.740; p < 0.001), CRP (ρ = 0.500; p < 0.001), and serum retinol (ρ = 0.301; p = 0.004). Inverse correlations were found with HDL-cholesterol (ρ = -0.358; p = 0.001), fiber intake (ρ = -0.328; p = 0.002), and the lactulose/mannitol ratio (ρ = -0.214; p = 0.044). Serum retinol was inversely correlated with the lactulose/mannitol ratio (ρ = -0.373; p < 0.001) and lactulose excretion (ρ = -0.370; p < 0.001), but not with mannitol excretion (ρ = 0.067; p = 0.530). In the adjusted logistic regression, higher retinol levels were significantly associated with overweight/obesity (AOR = 1.781; 95% CI: 1.012-3.134; p = 0.045).

Overweight and obese individuals showed lower intestinal permeability and higher serum retinol levels, despite similar dietary intake. Retinol was independently associated with overweight/obesity, suggesting complex interactions between vitamin A status, metabolic alterations, and intestinal barrier function. These changes may warrant further investigation and clinical attention.