Reduced plasma antioxidant concentrations and increased oxidative DNA damage in inflammatory bowel disease

Background: Oxidative stress is believed to play a key role in the pathogenesis of inflammatory bowel disease (IBD)-related intestinal damage. Circulating antioxidants may have a role to play in preventing free radical-mediated tissue injury. Methods: Plasma vita-min A, E and carotenoid concentrations, leukocytic genomic damage and 8-hydroxy-deoxy-guanosine (8-OHdG) concentration were determined in 46 ulcerative colitis (UC) patients, 37 Crohn disease (CD) patients and 386 controls. A 20 ml blood sample was taken from each subject for antioxidant and 8-OHdG measurements. A food frequency questionnaire was administered to a sample of subjects from each group to evaluate daily intake of dietary compounds. Results: Antioxidant concentration was significantly reduced in IBD patients, particularly in those with active disease, with respect to controls (P < 0.0001). 8-OHdG concentrations were significantly increased in IBD patients compared to controls, independent of disease activity (P < 0.05). No correlation was found between antioxidant and 8-OHdG concentrations. Carotenoid concentrations were significantly reduced in malnourished IBD patients (0.89 +/- 0.14 mu mol/l) compared to patients with normal or high body mass index (1.83 +/- 0.12 mu mol/l; P < 0.05), independent of disease activity or extension. Protein, fruit and vegetable intakes of IBD patients were significantly lower than those of controls. Conclusions: Depletion of antioxidants is likely to be important in the pathophysiology of IBD: UC and CD patients show increased free radical peripheral leukocyte DNA damage and decreased plasma antioxidant defenses. These results indicate the necessity of further studies to establish whether optimal vitamin status may improve the clinical course of UC and CD.