Efficacy and Safety of Encapsulated Bifidobacterium Longum BBH016 in Subjects With Lower Gastrointestinal Symptoms

Functional lower gastrointestinal (GI) symptoms such as abdominal pain, diarrhea, loose stools, and bloating are common in adults without identifiable organic disease and are associated with impaired quality of life and increased healthcare utilization. Growing evidence suggests that alterations in the gut microbiota may contribute to the development of these symptoms, supporting the potential role of probiotics as a therapeutic strategy. Bifidobacterium longum BBH016 is a probiotic strain isolated from a healthy donor and classified as Generally Recognized as Safe (GRAS). Preclinical studies have suggested that BBH016 may alleviate abdominal symptoms, reduce intestinal inflammation, and improve gut microbial balance. This investigator-initiated, randomized, double-blind, placebo-controlled clinical trial aims to evaluate the efficacy and safety of BBH016 capsules in adults with functional lower GI symptoms excluding constipation-predominant presentations. The study will be conducted at Seoul National University Bundang Hospital. A total of 88 participants aged 19-80 years will be randomized in a 1:1 ratio to receive either BBH016 capsules or placebo for 8 weeks (two capsules twice daily). Participants will be assessed at baseline, 4 weeks, and 8 weeks. The primary endpoint is overall improvement in GI symptoms at week 8 compared with baseline between treatment groups. Secondary endpoints include changes in individual symptom scores, IBS Symptom Severity Score (IBS-SSS), IBS Quality of Life (IBS-QoL), stool frequency and form assessed by the Bristol Stool Form Scale, and psychological well-being measured using the Hospital Anxiety and Depression Scale (HADS). Stool samples will also be collected to evaluate changes in the gut microbiome and their association with clinical outcomes.