★★★★★
- Accepting New Patients
Dr. Mark Tsuchiyose
Gastroenterology, Hepatology & Internal Medicine
Board-Certified Gastroenterologist and Hepatologist with over 35 years of experience providing compassionate, patient-centered and innovative care in the San Francisco Bay Area.
About Dr. Tsuchiyose
Dr. Mark M. Tsuchiyose has provided comprehensive gastrointestinal and liver care for over 35 years, treating a wide range of digestive and liver disorders with a personalized, patient-centered approach. His extensive training in diagnostic and therapeutic endoscopy allows him to pursue the best possible clinical outcomes for his patients.
Since 2014, Dr. Tsuchiyose has further expanded his practice through formal training and clinical experience in functional and holistic medicine. This shift was inspired by his daughter’s prolonged illness following post-infectious IBS and Lyme disease, which did not improve despite care from multiple specialists. This experience deepened his commitment to understanding root causes of chronic disease and thinking beyond conventional frameworks.
Through a functional understanding of pyloric valve dysfunction, Dr. Tsuchiyose has incorporated targeted nutritional supplementation to reduce bile-related injury, enabling many patients to discontinue long-term proton pump inhibitor (PPI) therapy and avoid associated side effects.
This same innovative approach has led to significant improvements in liver health. At the Center for Diabetes and Cardiometabolic Health (CDCH), Dr. Tsuchiyose has successfully reduced liver fat in approximately 90% of patients through focused metabolic and nutritional interventions.
In addition to caring for individual patients, Dr. Tsuchiyose has long been an advocate for fellow physicians, community, and public health.
- Over 35 years of clinical experience in gastroenterology and hepatology
- Performed thousands of diagnostic and therapeutic endoscopic procedures
- Consistent Adenoma Detection Rate on par with the national average
- Endoscopic complication rates lower than quoted national averages
- Assistant Clinical Professor of Medicine UCSF, San Francisco, CA (1996-2006)
- Medical Director, Seton Nutritional Support Team (1997–2000)
- Chief of Gastroenterology of Seton Medical Center, Daly City, CA (2002-2009)
- Chairman, Department of Internal Medicine, Seton Medical Center (2009–2013)
- Vice-President of Clinical Affairs & GI Therapeutic Lead, Adaptive Research (2021–2024)
- Vice-Chief of Staff Seton Medical Center, Daly City, CA (7/2022-6/2024)
- Chief of Staff Seton Medical Center, Daly City, CA (7/2024-present)
Leadership to Support Physicians
- President, Pacific Specialists Medical Group (1998–1999), advocating against unfair HMO practices
- President, Gastroenterology Specialty Network (1999–2000), addressing inequities in insurance and managed care systems
- President, Physicians for the Preservation of Private Practice - 2008 to 2010 to bring PCP and specialists together and garner the CCHP IPA contract
Community Engagement
- Board Member, Seton Foundation (2005–2008)
- Long-standing participant in the Hep B Free Program
Commitment to Public Health
- Founder, Center for Diabetes and Cardiometabolic Health (CDCH) at AHMC Seton Medical Center
- Member, Research Committee, Seton Medical Center (2022–Present)
- Proud parent of a daughter currently a third-year medical student at Tufts University with aspirations in advanced endoscopy
- Passionately involved in efforts to preserve and rehabilitate Seton Medical Center as a vital safety-net hospital
- Deeply committed to teaching and mentoring, beginning as an Assistant Clinical Professor at UCSF and continuing with residents in the NEMS program at Seton
- Strong believer in physical activity and healthy aging; enjoys squash, tennis, golf, skiing, Aikido, and strength training
- Lifelong learner with interests in books, media, travel, history, and regional cuisine
- Appreciates the arts and enjoys painting and sketching while traveling; aspiring ukulele student
- Dr. Tsuchiyose’s future focus is to expand clinical research and further develop other clinics to address the growing epidemic of chronic metabolic and liver disease.
We accept most major insurance plans. Please contact our office to verify coverage for your specific plan.
Accepted Insurance Plans:
- Medicare
- Blue Cross Blue Shield
- Aetna
- Cigna
- United Healthcare
Additional Plans:
- Brown and Toland
- Hills Physician
- Health Net
- Anthem
- And many more...
Please call (650) 993-6629 to verify your insurance coverage before your appointment.
Professional Training & Credentials
Dr. Tsuchiyose brings decades of specialized training and recognized expertise in gastroenterology, hepatology, and internal medicine.
Medical School
University of Southern California
Doctor of Medicine, 1983
Internship
LAC/USC Medical Center
1983-1984
Residency - Internal Medicine
Huntington Memorial Hospital
1984-1986
Fellowship - Hepatology
Huntington Memorial Hospital
1986-1987
Fellowship - Gastroenterology
LAC/USC
1987-1989
Advanced ERCP Training
Holland & Japan
International Training, 1989
Professional Recognition
Board Certified in Internal Medicine
Board Certified in Gastroenterology
Board Certified in Hepatology
Fellow, American College of Gastroenterology
Member, American Gastroenterological Association
Chief of Staff, Seton Medical Center (Current)
Areas of Expertise
Comprehensive digestive health care with specialized expertise in advanced endoscopic procedures, liver disease management, and functional GI medicine.
- Diagnostic and Therapeutic Endoscopy with expanded understanding of physiology to tailor personalized care
- Colonoscopy and Colon Cancer Screening with high ADR
- Acid reflux & GERD treatment with the understanding of bile gastritis and esophagitis and the unique proven protocol to manage this difficult subset of GERD patients
- All liver disease management including hepatitis B & C with particular interest and success with all fatty liver (MAFLD & MASH)
- ERCP (Endoscopic Retrograde Cholangiopancreatography)
- Pancreatic & Biliary Disorders
Dr. Tsuchiyose specializes in functional GI medicine to treat a wide range of digestive symptoms:
Research & Publications
Dr. Tsuchiyose has contributed to advancing medical knowledge through research and peer-reviewed publications throughout his career.
- Numerous retrospective comparative studies of liver diseases with R. Peters, MD (1975-1977)
- USC Liver Unit, electron microscopic characteristics of NANB Viral liver infections in chimpanzees and trace element spectrophotometry characteristics liver diseases with R. Peters, MD (1977-1979)
- H. Edmonston, MD. Data collection for AFIP Liver fascicle on cholangiocarcinoma (1980)
- Department of Obstetrics and Gynecology, physiologic changes of hot flushes (1985)
- Cornelius Dooley, MD, Campylobacter pylori in Barrett's esophagus (1988)
- Hepatitis B eradication of the virus and CCC component (present)
- Collaboration with Genentech to reduce fibrosis in the setting of MASH (1/2026)
- J. Weissman, MD, M. Tsuchiyose, R. Peters, MD, "Lack of response to recombinant Hepatitis B Vaccine in non-responders to the plasma vaccine". JAMA September, 1988 - 260:12, 23-30
- A. George, M. Tsuchiyose, C. P. Dooley "Sensitivity of the gastric mucosa to acid and duodenal contents in patients with non-ulcer dyspepsia", Neurology, July, 1986 - 101: 1, 3-6
- S. Stain, H. Cohen, M. Tsuchiyose, A. Donovan "Choledocholithiasis endoscopic sphincterotomy or common bile duct duration" Annals of Surgery, June, 1991 - 627-634
- M. Tsuchiyose, M. J. Tong, MD, T. Merrigan "Pulse prednisone and interferon in hepatitis B chronic active hepatitis"
- E. A. Tsuchiyose, Anupam Aditi, MD, K. Tsuchiyose, MS, M. Tsuchiyose, MD. Abstract presented at ACG, "Adenoma Detection Rate found to be independent of time of day in single site sample using individual endoscopists". October, 2017
- The effect of fatigue on ADR - Erika Tsuchiyose et al
- The positive effects of liver supplements on reduction of fatty liver, a single site's 6 months data. To be submitted to the 2026 American College of Gastroenterology national conference