Circulating antioxidants in ulcerative colitis and their relationship to disease severity and activity.

Oxygen free radicals produced by neutrophils are important in the pathogenesis of mucosal damage in ulcerative colitis. Vitamin A, vitamin E and cysteine in the plasma can scavenge free radicals. In the present study, plasma levels of vitamin A, vitamin E, cysteine, cystine and protein-bound cysteine were measured in active ulcerative colitis before and immediately after treatment of the active disease, and correlated with disease severity, extent and activity. Plasma vitamin A and cysteine were significantly reduced in active ulcerative colitis compared with controls. Levels of vitamin E, cystine and protein-bound cysteine were not significantly altered in active ulcerative colitis. Vitamin A and cysteine concentrations returned to normal levels (P < 0.05) within 2 weeks of treating active colitis. There were significant negative correlations between clinical severity and the plasma concentrations of vitamin A and cysteine. Plasma cysteine levels also correlated inversely to disease extent. Depletion of the circulating antioxidants, vitamin A and cysteine, in active ulcerative colitis is likely to be important in the pathophysiology of the disease.