Adjunct Associate Professor Kewin Siah has developed a specialised clinical and research programme focused on complex disorders of gut–brain interaction, gastrointestinal motility and gastrointestinal dysautonomia. His work centres on patients with persistent, multisystem symptoms who often require coordinated care across gastroenterology, neurology, surgery, psychology and dietetics.
He received advanced training in Japan and at the Oppenheimer Center for Neurobiology of Stress, University of California, Los Angeles, where he further developed his expertise in irritable bowel syndrome and brain–gut interactions.
Regionally and internationally, he is Secretary-General of the Asian Neurogastroenterology and Motility Association, Chair of the Rome Foundation Complementary and Integrative Medicine Section, and Chair of the ANMA–APAGE Disorders of Gut–Brain Interaction Education Taskforce. He is also a chief author of major Asian clinical guidelines and consensus reports on chronic constipation, gastro-oesophageal reflux disease and functional dyspepsia.
His research spans gastrointestinal dysautonomia, small fibre neuropathy, the gut microbiome, multi-omics, digital health and complementary and integrative medicine. He has led and contributed to multinational studies, clinical trials, professional education and international consensus initiatives aimed at improving the recognition and management of complex gastrointestinal disorders across Asia. He also serves as an Associate Editor of the Journal of Neurogastroenterology and Motility.
1. Barbara G, Aziz I, Ballou S, Chang L, Ford AC, Fukudo S, Nurko S, Olano C, Saps M, Sayuk G, **Siah KTH**, Van Oudenhove L, Simrén M. Rome Foundation Working Team Report on overlap in disorders of gut-brain interaction. *Nat Rev Gastroenterol Hepatol.* 2025;22(4):228–251. doi:10.1038/s41575-024-01033-9. PMID: 39870943. **Impact Factor: 57.5.**
2. Schol J, Huang IH, Carbone F, Fernandez LMB, Gourcerol G, Ho V, Kohn G, Lacy BE, Colombo AL, Miwa H, Moshiree B, Nguyen L, O’Grady G, **Siah KTH**, Stanghellini V, Tack J. Rome Foundation and international neurogastroenterology and motility societies’ consensus on idiopathic gastroparesis. *Lancet Gastroenterol Hepatol.* 2025;10(1):68–81. doi:10.1016/S2468-1253(24)00284-X. PMID: 39674226. **Impact Factor: 39.1.**
3. **Siah KTH.** Acid inhibitors and allergy: comorbidity, causation and confusion. *Nat Commun.* 2020;11(1):3950. doi:10.1038/s41467-020-17831-z. PMID: 32769978. **Impact Factor: 18.1.**
4. Wei DJ, Li HJ, Lyu AP, Bian ZX, **Siah KTH**, Zhong LLD. Bridging the Gap: A Comprehensive Study on Traditional Chinese Medicine Strategies for Managing Adult Irritable Bowel Syndrome. *Am J Chin Med.* 2024;52(6):1589–1611. doi:10.1142/S0192415X24500629. PMID: 39343992. **Impact Factor: 7.8.**
5. Mahadeva S, **Siah KTH**, Ghoshal UC, Suzuki H, Lee YY, Chuah KH, et al. Second Asian Consensus Report on Functional Dyspepsia (2025): Updated Recommendations. *J Gastroenterol Hepatol.* 2026;41(3):832–853. doi:10.1111/jgh.70222. PMID: 41656163. **Impact Factor: 3.5.**
6. Tang ASP, Quek J, Sulaimi F, Sim B, Kai TOS, Soon EY, et al. Probiotics for Irritable Bowel Syndrome: An Updated Systematic Review and Meta-Analysis With Trial Sequential Analysis. *J Gastroenterol Hepatol.* 2026;41(4):1131–1146. doi:10.1111/jgh.70322. PMID: 41820241. **Impact Factor: 3.5.**
7. Xiao Y, **Siah KTH**, Zhang M, Tay BWR, Chuah KH, Tan V, et al. Hydrogen and Methane Breath Test: The Asian Neurogastroenterology and Motility Association Monograph. *J Neurogastroenterol Motil.* 2026;32(2):150–171. doi:10.5056/jnm25185. PMID: 41952402. **Impact Factor: 3.3.**
8. Ren YP, Chan WL, Chuah KH, Kim YS, Nakajima A, Mahadeva S, et al. Bali Chronic Constipation Roundtable Report: Chronic Constipation Management in Asia. *J Neurogastroenterol Motil.* 2026;32(1):109–128. doi:10.5056/jnm25076. PMID: 41261564. **Impact Factor: 3.3.**
9. **Siah KTH**, Kim YS. Exploring the Atypical Allergy Spectrum in Disorders of Gut-Brain Interactions: From Food to Aeroallergens. *J Neurogastroenterol Motil.* 2024;30(2):125–128. doi:10.5056/jnm24040. PMID: 38576364. **Impact Factor: 3.3.**
10. Chan ACY, **Siah KTH.** Can Small Fiber Neuropathy Explain the Overlap Gastrointestinal and Non-gastrointestinal Symptoms in Some Irritable Bowel Syndrome Patients? *J Neurogastroenterol Motil.* 2024;30(1):116–118. doi:10.5056/jnm23039. PMID: 38173163. **Impact Factor: 3.3.**
• Academy of Medicine, Singapore
• Asian Neurogastroenterology and Motility Association
• Asian Pacific Association of Gastroenterology
• Rome Foundation
.jpg)