Study on the Effectiveness and Mechanism of Tong-Xie-Yao-Fang in Treating Diarrhea-predominant Irritable Bowel Syndrome

Inclusion Criteria: * IBS-D patients and healthy volunteers meeting diagnostic criteria; * Aged between 18 and 70; * Have not taken antibiotics, steroids and other hormones, Chinese herbal preparations (including oral and intravenous injections), microecological preparations or probiotics such as yogurt in the past week. * Patients sign informed consent forms and are willing to receive appropriate treatment, and volunteers are willing to cooperate in taking blood, urine, stool and other samples. Exclusion Criteria: * Patients with serious heart, liver, kidney and other major organ diseases, hematopoietic system, nervous system or mental diseases; * Other organic diseases of the digestive system (such as peptic ulcers), organic diseases such as tumors indicated by recent colonoscopy, or systemic diseases affecting digestive motility (such as hyperthyroidism, diabetes); * Need to continue to use drugs that may affect gastrointestinal function (antidiarrheals, antidepressants, anti-anxiety drugs, intestinal flora regulation drugs, antibiotics, etc.); * Have a history of drug allergy or severe food allergy for research purposes; * Patients under 18 years of age or over 75 years of age and pregnant or lactating women; * Severe negative life events occurred during treatment; * There is currently any form of psychotherapy in progress; * No intention to cooperate.