The present invention relates to a method of administering an effective dose of highly purified eicosapentaenoic acid as free-fatty acid (EPA-FFA) to reduce fecal calprotectin levels and reduce the risk of clinical relapse in UC patients. The eicosapentaenoic acid, in the free fatty acid (EPA-FFA) form, has a purity of at least 95%, and more preferably at least 99%.