Jeffrey Zheng-Hsien Ko, M.D. for UC Davis Health

Jeffrey Zheng-Hsien Ko, M.D.

Health Sciences Assistant Clinical Professor, Division of Gastroenterology and Hepatology

To see if Jeffrey Zheng-Hsien Ko is accepting new patients, or for assistance finding a UC Davis doctor, please call 800-2-UCDAVIS (800-282-3284).





Internal Medicine

Locations and Contact

UC Davis Midtown Ambulatory Care Center

Midtown GI Clinic
3160 Folsom Blvd
Sacramento, CA 95816

Get Directions

Phone: 916-734-0779

Additional Numbers

Clinic Phone


Physician Referrals

800-4-UCDAVIS (800-482-3284)

Philosophy of Care

Dr. Ko strongly believes in closely collaborating with the patient to create the most effective personalized treatment plans by utilizing the most up-to-date evidence and guidelines in the context of the patient's specific goals and preferences.

Clinical Interests

Dr. Ko is a general gastroenterologist who cares for adult patients with gastrointestinal conditions such as gastroesophageal reflux disease (GERD), abdominal pain, irritable bowel syndrome (IBS), small intestinal bacterial overgrowth (SIBO), Helicobacter pylori infection, chronic diarrhea, and constipation. Dr. Ko also routinely performs endoscopic procedures such as upper endoscopy and colonoscopy for diagnostic and cancer screening purposes. As a hospital-based gastroenterologist, he also sees patients hospitalized with gastrointestinal conditions regularly at UC Davis Medical Center.

Research/Academic Interests

Dr. Ko's academic interests include quality improvement in hospitalized patients with gastrointestinal conditions such as gastrointestinal bleeding and inflammatory bowel diseases. He also has significant interest in formal medical education at the medical school, residency, and fellowship levels.


Gastroenterology and Hepatology

Undergraduate School

B.A., Psychology, Northwestern University, Evanston IL 2009

Medical School

M.D., St Louis University School of Medicine, St. Louis MO 2015


Internal Medicine, Cedars-Sinai Medical Center, Los Angeles CA 2015-2016


Internal Medicine, Cedars-Sinai Medical Center, Los Angeles CA 2016-2018


Internal Medicine, Chief Resident, Cedars-Sinai Medical Center, Los Angeles CA 2018-2019


Gastroenterology & Hepatology, UC Davis Medical Center, Sacramento CA 2019-2022

Nirmal Mann Excellence in Fellow Research Award, UC Davis Division of Gastroenterology and Hepatology, 2022

Clinician Health and Wellbeing Innovation Award, UC Davis Clinician Health and Wellbeing, 2021

Academic Debate Winner, American Liver Foundation Northern California Academic Debates, 2021

Johnson S, Hoch JS, Halabi WJ, Ko J, Nolta J, Dave M. Mesenchymal Stem/Stromal Cell Therapy Is More Cost-Effective Than Fecal Diversion for Treatment of Perianal Crohn's Disease Fistulas. Front Immunol. 2022 Jun 17;13:859954. doi:10.3389/fimmu.2022.859954. PMID:35784367.

Johnson S, Ko J, Halabi WJ, Stondell J, Dave M. Fistula Healing Is Low After Fecal Diversion Surgery in Perianal Crohn's Disease. Inflamm Bowel Dis. 2022 Feb 1;28(2):e17. doi:10.1093/ibd/izab210. PMID:34448837.

Ko JZ, Johnson S, Dave M. Efficacy and Safety of Mesenchymal Stem/Stromal Cell Therapy for Inflammatory Bowel Diseases: An Up-to-Date Systematic Review. Biomolecules. 2021 Jan 11;11(1):82. doi:10.3390/biom11010082. PMID:33440772.

Gu P, Patel D, Lakhoo K, Ko J, Liu X, Chang B, Pan D, Lentz G, Sonesen M, Estiandan R, Lin E, Pimentel M, Rezaie A. Breath Test Gas Patterns in Inflammatory Bowel Disease with Concomitant Irritable Bowel Syndrome-Like Symptoms: A Controlled Large-Scale Database Linkage Analysis. Dig Dis Sci. 2020 Aug;65(8):2388-2396. doi:10.1007/s10620-019-05967-y. Epub 2019 Nov 21. PMID:31754993.

Gu P, Lew D, Oh SJ, Vipani A, Ko J, Hsu K, Mirakhor E, Pattisapu V, Bullen T, Fuller G, Spiegel BMR, Almario CV. Comparing the Real-World Effectiveness of Competing Colonoscopy Preparations: Results of a Prospective Trial. Am J Gastroenterol. 2019 Feb;114(2):305-314. doi:10.14309/ajg.0000000000000057. PMID:30730859.

Shrivastav M, Gounaris E, Khan MW, Ko J, Ryu SH, Bogyo M, Larson A, Barret TA, Bentrem DJ. Validation of near infrared fluorescence (NIRF) probes in vivo with dual laser NIRF endoscope. PLoS One. 2018 Nov 2;13(11):e0206568. doi:10.1371/journal.pone.0206568. Erratum in: PLoS One. 2019 Jan 7;14(1):e0210677. PMID:30388158.

Ahmed S, Almario CV, Chey WD, Robbins LA, Chang B, Ahn J, Ko J, Gu P, Siu A, Spiegel BMR. Electronic patient agenda forms: comparing agreement between the reason for specialty consultation reported by referring providers and patients. Inform Health Soc Care. 2019 Jan;44(1):105-113. doi:10.1080/17538157.2018.1437041. Epub 2018 Mar 6. PMID:29509054.

Ko J, Chen Y, Nepute J, Goodwill V, Garrett R, Befeler A, Lai JP. A Giant Primary Clear Cell Hepatocellular Carcinoma in a Young Woman without Cirrhosis. Clin Exp Pathol. 2015 Apr 28:5(3):224. doi:10.4172/2161-0681.1000224.

Santaolalla R, Sussman DA, Ruiz JR, Davies JM, Pastorini C, España CL, Sotolongo J, Burlingame O, Bejarano PA, Philip S, Ahmed MM, Ko J, Dirisina R, Barrett TA, Shang L, Lira SA, Fukata M, Abreu MT. TLR4 activates the β-catenin pathway to cause intestinal neoplasia. PLoS One. 2013 May 14;8(5):e63298. doi:10.1371/journal.pone.0063298. PMID:23691015.

Krishnan K, Komanduri S, Cluley J, Dirisina R, Sinh P, Ko JZ, Li L, Katzman RB, Barrett TA. Radiofrequency ablation for dysplasia in Barrett's esophagus restores β-catenin activation within esophageal progenitor cells. Dig Dis Sci. 2012 Feb;57(2):294-302. doi:10.1007/s10620-011-1899-0. Epub 2011 Sep 24. PMID:21948356.