Probiotics are friendly bacteria normally present in food products like yogurt whereas irritable bowel syndrome is a longstanding functional disorder characterized by abdominal pain and altered bowel habits either diarrhea or constipation dominant without a definitive etiology.

Study Hypothesis:Does probiotics(Saccharomyces boulardii improves daily bowel symptoms and quality of life in patients with diarrhea dominant irritable bowel syndrome?

Irritable bowel syndrome (IBS) is a common functional disorder and may lead to impaired social and personal function and can diminish quality of life.While the precise pathophysiology of IBS remains to be elucidated, dysmotility and altered visceral sensory perception are currently the most popular hypothesis. There has been a suggestion that some patients with IBS may harbor bacterial overgrowth leading to low grade inflammation, immune activation, and their symptoms may be ameliorated by its eradication.Probiotics, defined as live or attenuated bacteria or micro organism that confer a significant health benefit to the host.

• I. Firstly, probiotic organism exert antibacterial and antiviral effects.
• II. Probiotics could alter the composition of the gut flora, either directly through augmentation of commensal or indirectly through a reduction in pathogen related inflammation or bacterial fermentation.

Trial protocol:

Phase 1: placebo BID (1 week),both arms Phase 2: Randomization by pharmacy, placebo vs. active drug (6 weeks) Phase 3: placebo BID (1 week), both arms

-III. Probiotics have been demonstrated to exert anti-inflammatory effects at mucosal surfaces by reducing mucosal inflammation, decreasing immune mediated activation of enteric motor and sensory neurons and modifying neural traffic between the gut and central nervous system.

Saccharomyces Boulardii is a probiotic yeast and its role for the treatment of IBS has not been extensively investigated.

• Drug: Saccharomyces boulardii
• Drug: Methyl cellulose powder (low viscosity)

• Active Comparator: Receive active drug Saccharomyces boulardii 250mg twice a day for 8 weeks.
• Placebo Comparator: Placebo will be given twice a day for 10 weeks

Inclusion Criteria:

• Patients will be recruited from gastroenterology clinic at Aga Khan University hospital with diagnosis of diarrhea dominant irritable syndrome.
• Age between 18- 60 years.
• Male and female both.
• Organic gastrointestinal diseases excluded by baseline laboratory and sigmoidoscopy/colonoscopy and biopsy within last 2 years.
• All Patients need to satisfy ROME III criteria

Exclusion Criteria:

• Age < 18 and > 60 years
• Pregnant and lactating females
• Patients on laxatives or antidiarrheal drugs that could influence the motility of gut
• Patient on antibiotics or within 2 weeks of starting protocol.
• Not willing to participate
• Non-compliant in run in period.
• Patients taking Husk.
• Diabetic patients