Inclusion Criteria:

• 18 years or older diagnosed with active ulcerative colitis (UC) (with a Mayo score ≥4, with an endoscopic Mayo Clinic score ≥1, and disease that extended 15 cm or more from the anal verge) who had failed with mesalamine therapy
• Patients who were previously exposed to mesalamine or steroids will have a 30-day washout period before being enrolled
• Patients who were previously exposed to tumor necrosis factor (TNF) antagonists will have a 60-day washout period before being enrolled
• For patients who were previously exposed to glucocorticoids, immunosuppressive medications (i.e., azathioprine, 6-mercaptopurine, or methotrexate), or TNF antagonists, a documentation of unsuccessful previous treatment (i.e., lack of response or unacceptable adverse events) is required
• A diagnosis of ulcerative colitis (UC) confirmed by biopsy obtained at the index colonoscopy or flexible sigmoidoscopy

Exclusion Criteria:

• Patients who have been on semi-vegetarian diet before the trial will be excluded. 
• Other criteria include:
  • Pregnancy or lactation 
  • An unstable or uncontrolled medical disorder 
  • An anticipated requirement for major surgery 
  • History of subtotal colectomy with ileorectostomy or colectomy with ileoanal pouch 
  • Koch pouch, or ileostomy for UC  
  • Planned bowel surgery
• Unable to give informed consent
• Unable to swallow pills/capsules 
• Current diagnosis of fulminant colitis or toxic megacolon 
• Abdominal abscess 
• Symptomatic colonic stricture 
• Stoma 
• Disease limited to the rectum (ulcerative proctitis) 
• Current total parenteral nutrition 
• Positive Clostridium difficile stool assay 
• History of an infection requiring intravenous antimicrobial therapy within 1 month or oral antimicrobial therapy within 2 weeks 
• History of listeria 
• Histoplasmosis 
• Chronic or active hepatitis B or C infection 
• Human immunodeficiency virus 
• Immunodeficiency syndrome
• Untreated tuberculosis 
• History of central nervous system demyelinating disease 
• History of malignancy other than a successfully treated nonmetastatic cutaneous squamous cell or basal cell carcinoma or localized carcinoma in situ of the cervix 
• Evidence of dysplasia or malignancy on the screening colonoscopy/flexible sigmoidoscopy with biopsy  
• Any of the following laboratory abnormalities during the screening period: a) Hemoglobin level <8 g/dL, b) WBC count <3 × 109/L, c) Lymphocyte count <0.5 × 109/L, d) Platelet count <100k/L or >1200k/L, e) Alanine aminotransferase (ALT) or aspartate aminotransferase (AST) >3 × the upper limit of normal (ULN), f) Alkaline phosphatase >3 × ULN, g) Serum creatinine >2 × ULN
• Antibiotic use within past 14 days 
• Probiotics use within past 7 days