BACKGROUND: The purpose of our research was to evaluate the impact of supplementationwith antioxidative vitamins in children with chronic recurrent gastroduodenitis on the concentrationof malon-dialdehyde (MDA) in plasma and erythrocytes, and on activity of the antioxidant enzymes: dismutase(SOD), catalase (CAT) and glutathione peroxidase (GSH-Px). MATERIAL/METHODS: We studied 19 children (agefrom 13 to 16), diagnosed with chronic recurrent gastroduodenitis. The concentration of MDA was measuredby Buege and Aust method, while the antioxidant enzyme activity was measured before and after a two-monthcourse of supplementation with vitamins C and E: SOD by the Misra and Fridovich method, CAT by the Bearsand Seizer method, and GSH-Px by the Paglia and Valentine method. RESULTS: The average concentrationof MDA in erythrocytes in the studied children was significantly higher (38.59 nM/gHb) than in controlgroup (24.07 nM/gHb), but after supplementation was significantly reduced (p

Keywords: Adolescent, Dietary Supplements, Duodenitis, Erythrocytes, Malondialdehyde