This is a prospective, randomized, double-blind, placebo-controlled, parallel-group interventional clinical trial designed to evaluate the efficacy and safety of a Bacillus coagulans-based product in adult patients with mild to moderate Irritable Bowel Syndrome with predominant diarrhea (IBS-D), diagnosed according to Rome III criteria.

A total of 50 eligible male and female participants aged 18 to 65 years will be randomized in a 1:1 ratio to receive either Bacillus coagulans capsules or matching placebo for 8 weeks. The investigational product contains Bacillus coagulans (10⁶-10⁸ CFU) administered orally twice daily, morning and evening.

The primary objective is to assess the effect of the study product on IBS-D symptoms, including abdominal pain, gastrointestinal symptom severity, stool consistency, and stool frequency, using validated assessment tools such as Abdominal Pain Visual Analogue Scale (VAS), IBS Symptom Severity Scale (IBS-SSS), and Bristol Stool Form Scale (BSFS). Secondary assessments include changes in hematological parameters and lipid profile biomarkers, along with safety monitoring through vital signs and adverse event reporting.

Participants will attend four study visits: screening, baseline, Week 4, and Week 8. Weekly symptom recordings for abdominal pain and stool characteristics will be documented using participant diary cards throughout the treatment period.

Inclusion Criteria:

Male or female ≧ 18 - ≦ 65 years old. Signed informed consent. IBS-Diarrhea patient satisfying Rome III criteria.

Male and female subjects in age range of 18 - 65 years and satisfying the Rome III Criteria for mild to moderate IBS-Diarrhea (IBS-D):

Recurrent abdominal pain or discomfort, 3 days per month in the last 3 months (12 weeks), associated withmore than 2 of the criteria below. The criteria are fulfilled with symptoms onset 6 months prior to diagnosis Improvement with defecation. Onset associated with a change in stool frequency. Onset associated with a change in stool form (appearance).

At least two of the following, at least a quarter of occasions or days (25%):

Altered stool frequency (> 3 bowel movements/day). Altered stool form (loose/watery stools). Altered stool passage (urgency or feeling of incomplete evacuation). Passage of mucus. Bloating or feeling of abdominal distention.

Exclusion Criteria The patient will be excluded from the study if assessment by the treating investigator showed evidence for cardiovascular, respiratory, urogenital, gastrointestinal/hepatic, hematologic/immunologic, head, ears, eyes, nose and throat, dermatologic/psychiatric, allergy, major surgery or other diseases as revealed by history, physical examination and existing laboratory assessments which may interfere with the administration. Pregnant or lactating women. Females at child bearing age will be excluded unless they are using acceptable birth control measures (i.e. implants, injectables, combined oral contraceptives, some intrauterine contraceptive devices, sexual abstinence or a vasectomized partner) Patients requiring treatments with non-permitted medication (i.e. 5-HT3 antagonist, spasmolytics, anticholinergics, cholestyramine, anti latulence agents, metoclopramide, gastric-anti secretory agents (proton pump inhibitors; for indications other than Gastroesophageal Reflux Disease (GERD)), narcotics, anti-diarrheal drugs, and systemic steroids) Patients requiring the use of antibiotics either in medicine form of natural (e.g.

grapefruit seed extract, olive leaf extract, oil of oregano, colloidal silver and highly concentrated garlic preparations) Exercise and the use of complementary and alternative medicine for IBS symptoms (i.e. peppermint oil, cognitive behavior therapy) during the study should be maintained at the same level prior to the study. Patients exceeding the treatment limits of permitted medication [(more than 2 days/week during the study period): alginate, antacids and analgesics (limited to acetaminophen ≤ 1000 mg/day, acetylsalicylic acid or NSAIDS no more than 2 tablets/day), (stable dose throughout the study period, anti-depressants (must be on a stable dose > 3 months), fiber supplements, psyllium hydrophilic mucilloid, gastric anti secretory agents (only for GERD patients who are on a stable dose > 3 months; patients should be able to differentiate between IBS and GERD symptoms), acetylsalicylic acid ≤ 325 mg/day, sedatives. Deliverance medications: Mild laxatives only if necessary.]. Any other medications can be used without limits based on the clinical judgment of the treating investigator. Being in another clinical trial 4 weeks before entering the study. Constipated IBS patients. IBS-Diarrhea patients with un-treated lactose intolerance. Regular use of probiotics or using other probiotics during the course of the study.

Patients allergic to milk or soy products. Patients using catheters. Patients presented with rectal bleeding, weight loss, iron deficiency anemia, nocturnal symptoms and a family history of colorectal cancer, inflammatory bowel disease and celiac spruce. Patients over 50 diagnosed with Irritable Bowel Syndrome who have not had a colonoscopy in the last 5 years. Patients who have allergies for the active ingredients or any of the excipients Patients presented with any immune-compromised condition (such as AIDS, lymphoma, long term corticosteroid treatment) Patients presented with nausea, vomiting and fever.