Thomas Flass, MD, MS 

Pediatric Gastroenterologist and Nutrition Advocate

Dr. Flass holds 2 degrees in Nutrition and is board certified in both Pediatrics and Pediatric Gastroenterology. Prior to medical school he received an undergraduate degree in Human Nutrition from Cornell University, then went on to get a Master’s degree in Human Nutrition from Colorado State University in Fort Collins, CO. His research focus during that time was on omega–3 fatty acids effects in the brain.

After completing his Master’s degree, he attended medical school at the University of Colorado School of Medicine. He then completed a residency in Pediatrics and his fellowship in Pediatric Gastroenterology at Children’s Hospital Colorado, one of the top Pediatric training programs in the country. 

Dr Flass has been practicing Pediatric Gastroenterology and Nutrition in Montana since 2012, and helped to create an extensive outreach program to serve the needs of children in one of the most medically underserved areas of the United  States.

He believes in a nutrition first approach to medicine and gastroenterology. This involves looking for the real underlying cause of a child’s health issue, and not merely treating or masking the symptoms – often recommending dietary changes in conjunction with medications and nutritional supplements. He has given numerous public
lectures and Grand Rounds lectures on nutrition related topics to try to raise awareness as to how dietary choices can promote or heal disease. He is currently in the process of completing a book that condenses his 30 years of experience and the latest research into an evidence–based look at pediatric nutrition and why our dietary choices for our kids are so important.

Board Certifications

The American Board of Pediatrics – Pediatrics
The American Board of Pediatrics – Pediatric Gastroenterology



Children’s Hospital Colorado – Pediatric Gastroenterology, Hepatology and Nutrition



Children’s Hospital Colorado


Medical School

University of Colorado School of Medicine


Master’s Degree

Colorado State University  


Bachelor’s of Science

 Cornell University College of Human Ecology




My Story

Like many other healthcare providers, my journey and my worldview were shaped by my own health challenges as a child. For years I suffered from frequent bouts of abdominal pain and gastrointestinal distress, but was left with no diagnosis or effective management plan. “You have a sensitive stomach” was all I was told. As a teen, I kept a bottle of pepto or a roll of tums in my pocket at all times to try and ward off the next impending attack. No one at the time talked to me about diet, or how certain foods could be causing my symptoms.

It wasn’t until years later that I went through the most powerful transformation of my life. At the advice of some forward–thinking healthcare providers with whom I had the good fortune to work, I did an elimination diet – removing multiple potential food triggers from my diet. The results changed my life. Aside from the resolution of my GI symptoms, the difference in my energy and my ability to think and focus were profound. Without this experience, there is absolutely zero chance I would be a doctor right now.

Having this personal experience opened up a new world to me – a side of nutrition and medicine that is incredibly powerful, but woefully underutilized. It has caused me to always “think outside the box” and look at the relationship between food and medicine through a more integrative lens. It is the driving force that continues to propel me forward to explore how our food impacts our health and the health of our children.

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