Efficacy and Safety of Dietary Supplementation of Diamine Oxidase to Improve Symptoms in Patients With IBS

This project is a single center, randomized, controlled clinical trial evaluating the effects of DAO enzyme dietary supplement on symptoms of irritable bowel syndrome.

These participants are randomized to either a 4-week group with DAO enzyme dietary supplement or placebo. The participants are required to fill out IBS-SSS and IBS-QOL questionnaires and record their IBS symptom improvement, IBS treatment drug use, compliance and adverse reactions every evening. At the same time, the patients' diet is continuously recorded for 3 days by 24-hour diet review method in Visit 0, Visit 1 and Visit 2, respectively, to inform the patients to avoid large fluctuations in diet structure. On days 0, 14 and 28, the subjects are asked to visit the hospital offline. The staff check with the subjects in detail according to the scale and questionnaire contents, and review the general situation and questionnaire in the previous 2 weeks. On the 7th and 21st day, the staff contact the subjects online to provide guidance and remind the subjects to fill in the scale and questionnaire. In addition, oral mucosal samples, urine and feces will be collected for identifying mutations in the genetic DAO enzyme coding gene, histamine detection and 16sRNA sequencing, respectively.