Effects of a Prebiotic-Probiotic Combination on Constipation Symptoms and Quality of Life

This study aims to evaluate whether a combination of a prebiotic (1-kestose) and a probiotic (Lacticaseibacillus rhamnosus BBH112) improves gastrointestinal symptoms and quality of life in adults with constipation-related symptoms. A total of 40 adults aged 19 to 80 years will be enrolled in this randomized, double-blind, controlled trial. Participants will be randomly assigned to receive either the probiotic combined with the prebiotic or the probiotic combined with a placebo for 8 weeks. The primary objective is to compare overall satisfaction with gastrointestinal symptom improvement between the two groups after 8 weeks. The study will also assess changes in abdominal pain, bloating, bowel habits, stool consistency, quality of life, and psychological well-being. In addition, changes in the gut microbiome will be evaluated using stool samples collected before and after the intervention. The findings may help determine whether adding a prebiotic to probiotic supplementation provides additional benefits for adults experiencing constipation-related gastrointestinal symptoms.

\*\*Inclusion Criteria:\*\* 1. Korean men and women aged 19 to 80 years. 2. Adults experiencing constipation-related lower gastrointestinal symptoms, including abdominal pain or bloating, along with constipation symptoms such as excessive straining during defecation, hard stools (Bristol Stool Form Scale types 1-2), or fewer than three bowel movements per week. 3. No diagnosed organic gastrointestinal disease. 4. Colonoscopy performed within the previous 5 years, or at enrollment, confirming the absence of significant organic colonic disease. Colonoscopy reports from other institutions are acceptable. Individuals who underwent biopsy or polypectomy may be enrolled if the investigator determines that participation is appropriate after reviewing the results. 5. Women who are surgically sterile or women of childbearing potential with a negative urine or serum pregnancy test who agree to use appropriate contraception during the study. Appropriate contraceptive methods include oral contraceptives, intrauterine devices, double-barrier methods, or hormonal implants. Male participants must also agree to appropriate contraceptive measures during the study. 6. Individuals capable of understanding the study and communicating their decisions clearly, without significant uncontrolled neurological or psychiatric conditions. Individuals with adequately controlled neurological or psychiatric disorders may participate. 7. Individuals who voluntarily provide written informed consent to participate in the study. \*\*Exclusion Criteria:\*\* 1. Pregnant or breastfeeding women. 2. Individuals whose predominant gastrointestinal symptom is diarrhea. 3. Participation in another investigational drug trial within 3 months before Visit 1. Individual cases may be reviewed in consultation with the study monitor. 4. Any condition or circumstance that, in the investigator's judgment, may increase the risks associated with study participation or interfere with the conduct of the study. 5. Severe congestive heart failure or severe angina pectoris. 6. Diagnosed lactose intolerance or immunosuppression. 7. Current use of medications that may affect the study intervention or outcomes, including gastrointestinal medications, probiotics, intestinal regulators, or antibiotics, unless the following conditions are met: * Probiotic use may be discontinued at least 2 weeks before enrollment. * Antibiotics or gastrointestinal medications, including potassium-competitive acid blockers, proton pump inhibitors, histamine-2 receptor antagonists, pinaverium, or trimebutine, may be discontinued at least 4 weeks before enrollment. * Participants requiring continued gastrointestinal medications may be eligible if the type and dosage of these medications remain unchanged throughout the study period. 8. Uncontrolled hypertension, defined as systolic blood pressure greater than 160 mmHg or diastolic blood pressure greater than 100 mmHg at Visit 1, regardless of antihypertensive treatment. 9. Uncontrolled endocrine disorders (including diabetes mellitus), metabolic disorders (such as secondary hyperlipidemia), or hypothyroidism. Participants with a history of hypothyroidism may be eligible if they have received stable thyroid hormone replacement therapy for at least 4 weeks before the study visit and have a thyroid-stimulating hormone (TSH) level within the normal reference range at Visit 2. 10. Impaired renal function, defined as serum creatinine greater than 2.0 mg/dL at Visit 1, or the presence of nephrotic syndrome. 11. Diagnosis of malignancy within the previous 5 years, except for individuals considered cured. 12. Significant psychiatric instability or psychiatric disorders that are not adequately controlled with medication or psychiatric treatment. 13. Use of systemic corticosteroids within 1 month before Visit 1. 14. History of abdominal surgery other than appendectomy, cesarean section, hysterectomy, or hernia surgery. Individuals with other abdominal surgical histories may be enrolled if the investigator determines that participation is appropriate. 15. Any other condition that, in the investigator's judgment, makes the individual unsuitable for participation in the study.