Effects of Vitamin D on Gut Microbiota, Intestinal Barrier in IBS-D Patients

Inclusion Criteria: * ①IBS-D patients meeting the Roman IV diagnostic criteria: recurrent abdominal pain, averaging at least 1 day per week in the last 3 months, with 2 or more of the following: associated with defecation, accompanied by changes in defecation frequency, accompanied by changes in fecal properties or appearance. (Symptoms have been present for at least 6 months before diagnosis, and meet the above diagnostic criteria in the last 3 months; \>1/4 (25%) stools were Bristol Stool Scale type 6 or 7, and \<1/4 (25%) stools were Bristol Stool Scale type 1 or 2); ② The age ranged from 18 to 65. Exclusion Criteria: * ① History of other gastrointestinal diseases, such as inflammatory bowel disease, infection, cancer, abdominal radiation or surgery, hepatobiliary and pancreatic diseases; ② Taking vitamin D drugs, calcium, contraceptives, glucocorticoids, probiotics, antibiotics, antidepressants, etc.; ③ Pregnancy and lactation; ④ Diabetes mellitus, thyroid disease, osteoporosis, etc.; ⑤ Complicated with serious heart, liver, lung, kidney, blood, serious mental diseases and other systemic diseases; (6) Boston Intestinal Preparation Scale score \<6; The cecum was not detected by endoscopy. ⑦ Unwilling to participate or unable to give informed consent.