Human experimental study on the effect of probiotics combined with prebiotics on ulcerative colitis: a randomized double-blind controlled trial

INTERVENTION: Experimental group:Probiotics and prebiotics;placebo group:maltodextrin; CONDITION: Ulcerative colitis PRIMARY OUTCOME: clinical activity index; SECONDARY OUTCOME: Sigmoidoscopy score;bowl habit index;Inflammation status score of colorectal biopsy tissue samples;Immunohistochemical analysis of inflammatory markers in biopsies;The index of the barrier function of blood midgut mucosa;Fecal inflammation index;Microgenomics of intestinal mucosa; INCLUSION CRITERIA: 1. Patients with unlimited gender, aged >= 18 years, willing to sign informed consent; 2. Patients who meet the diagnostic criteria in the consensus opinion on the diagnosis and treatment of inflammatory bowel disease (2018 Edition); 3. Patients with mild or moderate disease course > 3 months; 4. Patients who have not received antibiotic treatment or taken commercial probiotic preparations in the past three months; 5. HIV negative, HTLV I / II negative, fecal culture negative, C diff toxin negative, CMV negative.