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 pathogen esis of inflammatory bowel disease (IBD)-related intestinal damage. Circula ting antioxidants may have a role to play in preventing free radical-mediat ed tissue injury. Methods: Plasma vita-min A, E and carotenoid concentratio ns, leukocytic genomic damage and 8-hydroxy-deoxy-guanosine (8-OHdG) concen tration were determined in 46 ulcerative colitis (UC) patients, 37 Crohn di sease (CD) patients and 386 controls. A 20 ml blood sample was taken from e ach subject for antioxidant and 8-OHdG measurements. A food frequency quest ionnaire was administered to a sample of subjects from each group to evalua te daily intake of dietary compounds. Results: Antioxidant concentration wa s 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 o f disease activity (P < 0.05). No correlation was found between antioxidant and 8-OHdG concentrations. Carotenoid concentrations were significantly re duced in malnourished IBD patients (0.89 +/- 0.14 mu mol/l) compared to pat ients 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 vegetab le intakes of IBD patients were significantly lower than those of controls. Conclusions: Depletion of antioxidants is likely to be important in the pa thophysiology of IBD: UC and CD patients show increased free radical periph eral leukocyte DNA damage and decreased plasma antioxidant defenses. These results indicate the necessity of further studies to establish whether opti mal vitamin status may improve the clinical course of UC and CD.