Discuss the primary factors that may be involved in IBS etiology. You must include in your discussion the possible roles of genetics, infection, and serotonin

Question

What will be an ideal response?

Answer 1

• Unknown cause
• Genetic predisposition: Genes that control serotonin receptors may make certain people more prone to IBS
• Gender: Affects more women than men
• Altered immune response stimulated by food sensitivity
• Patients may be able to identify certain foods that exacerbate symptoms
• Fermentable oligosaccharides, disaccharides, monosaccharides, and polyols or sugar alcohols (FODMAPs) may play a role in the development of IBS
• Altered microbial environment in the colon
- Abnormal colonic fermentation (partial digestion of food in the large intestine that may lead to excessive gas production as a by-product)
- Includes small intestine bacterial overgrowth
• Elevated inflammatory response to gastroenteritis (infection)
• Specific bacteria documented with gastroenteritis in the development of IBS:
• Salmonella
• Blastocystis hominis
• Campylobacter
• Parasites like Trichinella spiralis
• Heightened or abnormal communication between GI tract and muscle
• Increased sensitivity to the enteric system that changes motility
- Stimuli that most people would not react to cause symptoms of urgency, diarrhea, or constipation in IBS patients
- Stress and other psychological factors may exacerbate symptoms
• Commonly associated with celiac disease, Inflammatory bowel disease - not causes but these often co-exist with IBS.
• Abnormal release, transport, or recognition of serotonin
- 95% of serotonin is found in the GI tract, and serotonin can be either stimulatory or inhibitory to the GI tract, which is why people may have diarrhea, constipation, or a mix with IBS.
- Serotonin can either cause stimulation of acetylcholine, which causes muscle contraction, or it can cause release of nitric oxide, which relaxes smooth muscle in the GI tract.
- Altered serotonin levels are well documented in IBS patients.
• Documented reduced levels of serotonin in IBS-C patients
• Documented elevated levels of serotonin in IBS-D
• Although there is documentation, the exact role of serotonin in IBS is not understood

• Altered GI mucosal permeability may be caused by these previously discussed triggers and lead to inflammation and an altered perception of pain.