Inclusion Criteria:  Participants aged 18 to 80 years old. Participants who had been diagnosed with colorectal cancer or advanced colorectal polyps for the first time according to pathology results. Participants who had signed informed consent. Participants must have the ability to complete the questionnaires of the study.  Exclusion Criteria:  Participants who had a positive personal history of colorectal polyps. Participants who had a positive personal history of colorectal cancer. Participants who had a positive personal history of other gastrointestinal diseases, such as inflammatory bowel disease， intestinal tuberculosis, or irritable bowel syndrome. Participants who had undergone a colonoscopy or other procedure requiring bowel preparation in the last two months. Participants who had been hospitalized for any reason in the last two months. Participants who had consumed antibiotics for any reason in the last three months. Participants who had consumed prebiotic supplements regularly in the last year. Participants who had other physical conditions that didn't suitable to participate in the study, such as severe cardiovascular diseases, serious mental illness, or pregnant status.