Backgroundn-3 Polyunsaturated fatty acids (PUFAs) have been suggested as a treatment for ulcerative colitis (UC). However, the efficacy of n-3 PUFAs against UC has not been examined in children. Therefore, the authors investigated the effects of eicosapentaenoic acid (EPA) on fatty acid composition and leukotriene (LT) production in children with UC.MethodsFor 2 months the authors administered highly purified EPA ethyl ester (EPA-E) (1.8 g/d) to children with UC in remission. Colonic mucosal histology, fatty acid composition of erythrocyte membrane phospholipids, and LTB4production by leukocytes and colonic mucosa were measured before and 2 months after the initiation of EPA-E treatment.ResultsNo patients relapsed during the study period, and no significant differences were detected in laboratory findings obtained before and 2 months after the initiation of EPA-E ingestion. There were no significant differences in mucosal histologic scores before and 2 months after EPA-E treatment. The EPA levels in erythrocyte membranes 2 months after the initiation of EPA-E treatment were significantly higher than before treatment, but the other fatty acids showed no significant changes. LTB4production by leukocytes and rectal mucosa after 2 months of EPA-E treatment was significantly lower than before treatment.ConclusionEPA-E treatment increased the levels of EPA in erythrocytes and decreased LTB4levels produced by leukocytes and colonic mucosa. To assess the concomitant clinical changes, we should examine the long-term effects of EPA-E ingestion on the maintenance of remission in children with UC.