Gut feeling: can a friendly bacteria soothe your stomach?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Male or female participants aged 19 to 80 years. 2. Subjects with lower gastrointestinal (GI) symptoms (diarrhea, loose stools, abdominal bloating, or excessive gas) in whom constipation is not the predominant symptom. 3. Subjects who have undergone colonoscopy within the past 5 years, or who will undergo colonoscopy after enrollment, with confirmation of no organic abnormalities in the colon. Records from another hospital within 5 years may be accepted. If colonoscopy included biopsy or polypectomy, subjects may be eligible if the investigator confirms no clinically significant abnormality. 4. Surgically sterile women or women of childbearing potential with a negative pregnancy test (urine hCG or serum β-hCG). Women of childbearing potential must agree to use appropriate contraception (e.g., oral contraceptives, intrauterine device \[IUD\], double-barrier method, or hormonal implant) throughout the study. 5. Subjects without major neurological or psychiatric disorders that impair decision-making capacity. Those with such conditions may still be eligible if deemed adequately controlled with medication or therapy. 6. Subjects who voluntarily provide written informed consent after receiving adequate explanation of the study. Exclusion Criteria: 1. Subjects with constipation as the predominant lower GI symptom. 2. Pregnant or breastfeeding women. 3. Participation in another clinical trial and receipt of an investigational product within 3 months prior to screening. 4. Any condition judged by the investigator to pose a risk to the subject or interfere with study participation. 5. Severe congestive heart failure or severe angina. 6. Subjects with lactose intolerance or immunosuppression. 7. Use of medications that may affect the study product (e.g., GI medications, probiotics, antibiotics). Probiotics: may participate if discontinued ≥2 weeks before enrollment. Antibiotics or GI medications (potassium-competitive acid blocker, proton pump inhibitor, H2 receptor antagonist, pinaverium, trimebutine, etc.): may participate if discontinued ≥4 weeks before enrollment. If ongoing GI medication use is necessary, dose and regimen must remain unchanged during the study. 8. Uncontrolled hypertension (systolic BP \>160 mmHg or diastolic BP \>100 mmHg at screening), regardless of current therapy. 9. Uncontrolled endocrine or metabolic disease (e.g., diabetes, secondary hyperlipidemia) or hypothyroidism. Patients with hypothyroidism may be included if on stable replacement therapy for ≥4 weeks and TSH is within normal range at screening. 10. Impaired renal function (serum creatinine \>2.0 mg/dL) or nephrotic syndrome at screening. 11. History of malignancy within the past 5 years (except those judged cured). 12. Major psychiatric instability or psychiatric disorders not adequately controlled by therapy. 13. Use of systemic corticosteroids within 1 month prior to screening. 14. History of abdominal surgery other than appendectomy, cholecystectomy, cesarean section, hysterectomy, or hernia repair. Other abdominal surgeries may be allowed if deemed appropriate by the investigator. 15. Any other condition judged by the investigator to make the subject unsuitable for participation.