Effects of Eicosapentaenoic Acid on Subjects at High Risk for Colorectal Cancer

Arm: experimental Inclusion Criteria: * Patients with ulcerative colitis (diagnosed based on clinical criteria, endoscopic and histological) lasting over 8 years, with no clinical activity (SCCAI = 0), and in stable treatment (without any change in treatment in the previous 3 months) with mesalamine, immunomodulators and / or biologics. * Baseline fecal calprotectin\> 150 micrograms / g. * Signed informed consent. Exclusion Criteria: * Patients receiving systemic steroids in the two months prior to study entry. * Patients taking concomitant warfarin or other blood thinners. * Known or suspected hypersensitivity to eicosapentaenoic acid/omega 3. * Women who are pregnant or of childbearing age who do not accept the use of contraceptive methods specified in the study (oral contraception, IUDs) and breastfeeding women. * Patients with severe medical conditions that, in the opinion of the investigator, contraindicate the patient's participation in the study. * Changes of treatments and / or use of experimental drugs within 3 months before inclusion in the study. * Use of Probiotics Arm: no intervention Inclusion criteria * Subjects undergoing screening colonoscopy within the regional colorectal cancer screening programme * Signed informed consent * Polypectomy with biopsy forceps. Exclusion criteria * HBV-positive, HCV-positive, HIV-positive or otherwise affected by infectious diseases * Subjects undergoing chemo and radiation therapy within six months prior to surgery * Patients receiving systemic steroid in the two months prior to study entry * Patients undergoing antibiotic therapy within three months prior to the study * Patients treated with probiotics