Decrease in serum protein carbonyl groups concentration and maintained hyperhomocysteinemia in patients undergoing bariatric surgery.

BACKGROUND: Human obesity is associated with oxidative stress but the factors contributing to the increase of reactive oxygen species (ROS) production remain unknown. We evaluated the association between serum homocysteine concentration, which may increase ROS production, and serum protein carbonyl groups concentration before and after bariatric surgery.
METHODS: Serum protein carbonyl groups and serum homocysteine concentrations, as well as obesity markers, were compared in 18 obese patients before and 6 months after bariatric surgery. Ten healthy individuals with normal body mass index (BMI) served as controls.
RESULTS: Before bariatric surgery, obese patients displayed approximately 50% higher serum protein carbonyl groups concentration than control subjects. After surgery, serum protein carbonyl groups concentration decreased and matched values observed in controls. Serum homocysteine concentration was also elevated in obese patients, but in contrast to protein carbonyl groups, did not change after surgery. The body weight, BMI, HOMA-IR, serum leptin, triacylglycerols, LDL/HLD cholesterol ratio, insulin, and glucose concentrations were higher in obese patients as compared to controls, and decreased after bariatric surgery.
CONCLUSIONS: This study demonstrates that bariatric surgery has protective effect on oxidative protein damage and improves several laboratory parameters including serum lipid concentration and insulin resistance. However, bariatric surgery does not cause a decrease in serum homocysteine concentration, a risk factor for the development of cardiovascular diseases. Collectively, the results presented in this paper suggest that serum homocysteine concentration is not directly associated with oxidative stress in obese patients after bariatric surgery.