This study was conducted in two phases. In Phase I, 40 UC participants, 40 CD participants, and 40 colitis participants were randomly assigned in a 1:1 ratio to the experimental group and the control group, respectively. The study included a screening period (1 week), a double-blind treatment period (24 weeks), an exit examination (1 day), and a safety follow-up period (4 weeks). After providing informed consent, participants who met the inclusion criteria and those who did not meet the exclusion criteria were randomly assigned, in a 1:1 ratio, to receive either the trial (probiotic 6600 capsules) or the control group (placebo). The clinical remission rate (SCCAI score ≤2 and no single subscore >1) after 24 weeks of treatment was calculated. Mayo score ≤2 and no single subscore >1; CDAI score ≤2 and no single subscore >1) were used as the primary efficacy index.

Inclusion Criteria:

1. Ulcerative colitis (UC) : met the clinical diagnostic criteria of UC "Chinese Guidelines for the Diagnosis and Treatment of Ulcerative Colitis (2023, Xi 'an)", and modified Mayo score ≥4 points;
2. Crohn's disease (CD) : met the clinical diagnostic criteria of CD "Chinese Guidelines for the Diagnosis and Treatment of Crohn's Disease (2023, Guangzhou)", and CDAI score ≥220;
3. Colitis: clinical diagnosis of colitis and modified SCCAI score ≥3; 3.
4. The age of signing the informed consent form was from 18 to 75 years old (including the cut-off value, male and female were not limited);
5. Complete medical history;
6. From the time of informed consent until 3 months after the last dose of dose, the participant committed to not having any plans to have children or to have any plans to donate sperm or eggs, and to voluntarily use non-pharmacologic contraception;
7. Fully understand the content, process and possible adverse reactions of the trial, voluntarily participate in the trial, and sign the informed consent.

Exclusion Criteria:

1. Taking prebiotics or probiotics in the past 2 weeks or allergic to intervention preparations;
2. Short bowel syndrome, abdominal abscess, toxic megacolon, intestinal perforation, active fistula of digestive tract, severe intestinal stenosis with obstructive symptoms, suspected intestinal obstruction, total colectomy;
3. Other autoimmune diseases, hematological diseases, tumors, acute infections, severe hepatic and renal insufficiency (ALT>2 times the upper limit of normal), severe diseases such as neutropenia, heart failure, organic heart disease, viral hepatitis B, liver cirrhosis, renal impairment (serum creatinine > 2mg/dL or 177mmol/L), AIDS And mental disorders;
4. History of psychoactive substance abuse;
5. A history of drug or other dependent substance abuse, or heavy alcohol consumption in the last 2 weeks (i.e. 28 standard units per week for men and 21 standard units per week for women (1 standard unit contains 14g of alcohol, such as 360mL of beer or 25mL of 40% spirits or 150mL of wine); Heavy drinkers during the trial;
6. Pregnant or breastfeeding women, or planning to become pregnant in the next 6 months;
7. Nervous system diseases such as Alzheimer's disease, stroke, Parkinson's disease;
8. Participated in other clinical trials within the past 6 months;
9. Incomplete medical record information (including gender, age, diagnostic information, colonoscopy results, pathological diagnosis results and other demographic data, etc.);
10. Other investigators deemed ineligible for enrollment.