Irritable Bowel Syndrome (IBS): Subtypes, Visceral Hypersensitivity, and Low-FODMAP Diet
Irritable Bowel Syndrome (IBS) is a disorder of gut-brain interaction (DGBI) affecting roughly 10% of the global population, characterized by recurrent abdominal pain associated with altered bowel habits. Review Rome IV diagnostic criteria, IBS subtypes (IBS-C, IBS-D, IBS-M), visceral hypersensitivity, Small Intestinal Bacterial Overgrowth (SIBO), and the 3-phase Low-FODMAP elimination and reintroduction protocol.
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Quick Summary & Key Findings
Irritable Bowel Syndrome (IBS) is diagnosed under Rome IV criteria as recurrent abdominal pain at least 1 day per week for 3 months, related to defecation and associated with a change in stool frequency or form. The most clinically validated dietary therapy is the 3-phase Low-FODMAP diet (Elimination, Reintroduction, and Personalization), which reduces poorly absorbed short-chain fermentable carbohydrates that cause gas distension, osmotic diarrhea, and visceral pain in sensitive guts.
For decades, patients presenting with chronic bloating, severe cramping, and unpredictable bowel habits were frequently told that their symptoms were 'all in their head' after routine colonoscopies and blood tests returned completely normal. Today, neurogastroenterology recognizes Irritable Bowel Syndrome (IBS) not as an imaginary complaint, but as a well-defined Disorder of Gut-Brain Interaction (DGBI).
In IBS, complex bidirectional dysregulation between the enteric nervous system (the 'second brain' in the gut) and the central nervous system produces visceral hypersensitivity—a lowered pain threshold where normal physiological intestinal gas and digestive contractions are perceived by the brain as sharp, distressing pain.
By classifying patients into precise clinical subtypes and applying the evidence-based 3-phase Low-FODMAP protocol developed by Monash University, clinicians and dietitians can resolve debilitating digestive symptoms in over 70% of IBS sufferers.
The Rome IV Diagnostic Criteria and IBS Subtypes
The 3-Phase Low-FODMAP Protocol (Monash University)
Gut-Brain Neuromodulators and Psychological Therapies
Frequently Asked Questions
Dr. Randhir Sud, MBBS, MD, DM, MAMS
Chairman, Institute of Digestive & Hepatobiliary Sciences, Medanta – The Medicity • MBBS, MD, DM (Gastroenterology)Dr. Randhir Sud is the Chairman of the Institute of Digestive and Hepatobiliary Sciences at Medanta – The Medicity, Gurugram. Recipient of the Padma Shri award, he is a pioneer in therapeutic gastrointestinal endoscopy, pancreatic-biliary disorders, and digestive health with over 35 years of clinical practice.
References & Clinical Resources
- Clinical Research Faculty & Editorial Team. ACG Clinical Guideline: Management of Irritable Bowel Syndrome (2020-2026). [Access Resource Link] — The American Journal of Gastroenterology
- Clinical Research Faculty & Editorial Team. Efficacy of the Low FODMAP Diet for Treating Irritable Bowel Syndrome: The Evidence to Date (2020-2026). [Access Resource Link] — Clinical and Experimental Gastroenterology
- Clinical Research Faculty & Editorial Team. Rome IV Diagnostic Criteria for Disorders of Gut-Brain Interaction (2020-2026). [Access Resource Link] — Gastroenterology
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