Evaluation of Oxidative Stress Status in Obese Patients after Bariatric Surgery

INTRODUCTION: This study aimed to evaluate the changes in oxidative stress markers in obese patients after bariatric surgery.


METHODS: The study included a total of 90 obese adults, divided into two groups: those who underwent bariatric surgery (case, n=45) and those who did not (control, n=45). Parameters such as 8-hydroxy-2-deoxyguanosine (8-OHdG; oxidative DNA damage), NADPH oxidase 2 (NOX2), NADPH oxidase 4 (NOX4), and thiol-disulfide homeostasis were compared in both groups.
RESULTS: 73.3% of the participants were female; age distribution was similar between groups (p=0.698). Body mass index (BMI) was lower in the case group compared to the control group (31.5±7.2 vs. 38.2±3.7 kg/m²; p<0.001). Native thiol levels were lower in the case group (135.9±55.6 vs. 154.3±38.0 µmol/L; p=0.014) and 8-OHdG was higher (7.6±1.8 vs. 6.5±2.1 ng/mL; p=0.015); NOX2 and NOX4 levels were similar (p>0.05). In the case group, those with a BMI change ≥13 kg/m² had higher native thiol levels (p=0.034) and lower 8-OHdG levels (p=0.045). A positive correlation was found between BMI change and native thiol levels (r=0.363; p=0.017). As the amount of weight loss increased, the disulfide/native thiol ratio decreased (r=−0.389; p=0.013) and the native/total thiol ratio increased (r=0.322; p=0.040).
DISCUSSION AND CONCLUSION: Although overall oxidative stress markers (high 8-OHdG, low native thiol) were observed in obese patients who underwent bariatric surgery, improvements in oxidative stress markers were detected in those with greater BMI reduction. The findings suggest that effective weight loss after surgery may increase antioxidant capacity and reduce DNA oxidative damage. Long-term prospective studies are needed to clarify this relationship.

Keywords: Obesity, Bariatric surgery, Oxidative stress,, 8-OHdG, NOX2, NOX4, Thiol-disulfide balance