Background: There are conflicting epidemiological studies regarding the association between selenium (Se) and metabolic disorders. Furthermore, the pathophysiological links between Se and metabolic dysfunction-associated steatotic liver disease (MASLD) have not yet been fully elucidated. Therefore, we evaluated the association between serum Se levels and the clinical features of MASLD and the inflammatory and oxidative stress markers in these patients as potential risk factors for the progression of this disease. Methods: This cross-sectional study involved 150 patients aged 20 to 50 years who were newly diagnosed with MASLD. Oxidative stress was evaluated by measuring serum thiobarbituric acid reactive substances (TBARS), total antioxidant capacity (TAC), and the activities of erythrocyte superoxide dismutase (SOD) and glutathione peroxidase (GPx). Tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and transforming growth factor beta (TGF-β) were measured as inflammatory markers. A one-way analysis of variance (ANOVA), Pearson chi-square test, Kruskal–Wallis test, and multiple linear regression were employed for data analysis. Results: We observed a significant inverse association between serum Se concentrations and liver steatosis severity in the participants. There was a significant decrease in serum concentrations of insulin and the homeostasis model assessment of insulin resistance (HOMA-IR), triglycerides, TNF-α, and TBARS with ascending quartiles of serum Se. Conversely, the mean serum levels of TAC and erythrocyte GPx activities exhibited a consistent increasing trend in relation to rising serum Se concentrations. However, no significant trends were identified for serum FSG, IL-6, TGF-β, or erythrocyte SOD activities across the varying levels of serum Se. Conclusions: Our results demonstrate that decreased serum selenium levels in Iranian patients with MASLD correlate with elevated inflammatory markers, increased oxidative stress, and more severe liver steatosis.
