Inclusion Criteria:  Patients aged 18 or over Active UC defined as a Mayo score (7) >3 A Mayo endoscopic score (7) >0 Females of child-bearing potential must be willing and able to use acceptable contraception as per Appendix III. II. b. Toxicity section of the Health Canada Guidance  Exclusion Criteria:  Participating in another intervention study for UC Unable to give informed consent Severe comorbid medical illness Severe UC requiring hospitalization. Increase in medical therapy for UC in the last 12 weeks. Continued treatment with 5-ASA, azathioprine, 6-mercaptopurine or anti-TNF therapy (e.g. infliximab) will be permitted if taken at stable dose for ≥12 weeks prior to randomization. Relapse on a stable dose (same dose for at least 2 weeks) or a tapering dose of steroids will also be permitted provided the dose of steroid is not increased again. Stable intake of probiotic therapy also permitted. Antibiotic therapy in the last 30 days. Pregnant women. Patients with clinically significant hepatic dysfunction at the time of screening: ALT > 5 times the upper normal range. Patients with clinically significant renal dysfunction at the time of screening: serum creatinine > 300 µmol/L Any condition, in the opinion of the investigator, that the treatment may pose a health risk to the subject.