Our Staff

Dr Liz Cruz


Dr. Cruz graduated from college in 1988 with a B.S. in Medical Technology. Prior to Medical School, she taught English for one year in Bangkok Thailand. In 1989, Dr. Cruz began her formal career in medicine by attending Loma Linda University School of Medicine in California. During medical school, Dr. Cruz was part of a student / staff physician team, which provided relief work to the natives along the Amazon River. She graduated from medical school in 1993 and then went on to do her Internal Medicine Internship under the auspices of the U.S. Navy at the Naval Hospital, Oakland, California.

Upon the closure of the Naval Hospital in Oakland, Dr. Cruz transferred and completed her internal medicine residency at the University of California, San Francisco. In 1996, she was deployed to Guam to fulfill her commitment to the U.S. Navy. While in Guam, she served as a Staff Internist at the U.S. Naval Hospital. During her active duty years in the Navy, she received the Meritorious Unit Commendation Medal as well as the Humanitarian Service Medal and the National Defense Medal for service during Operation Desert Storm. During her last two years in Guam, she was the Head of the Internal Medicine Division at the U.S. Naval Hospital.

In 2000, she went back to the University of California, San Francisco where she completed her training in Gastroenterology (GI). In 2004, Dr. Cruz moved to Arizona to join the Arizona Medical Clinic in Peoria. For two and a half years she served as a full-time gastroenterologist in both the outpatient and inpatient settings doing the full range of general gastroenterology including endoscopic procedures as well as hepatology. In January 2007, Dr. Cruz joined Estrella Gastroenterology in Goodyear, Arizona. In January 2008, she opened the doors to her own practice, Dr. Liz Cruz Partners in Digestive Health.

Dr. Cruz was born in Los Angeles, California and was raised in Orlando, Florida. She speaks fluent Spanish and enjoys her family, traveling, jazz music, and photography.

Dr. Cruz is a Diplomate of the American Board of Internal Medicine and the American Board of Gastroenterology. She is a member of the American Gastroenterological Association and the American Society for Gastrointestinal Endoscopy.

Maureen Tyner – RN, MSN, DNP-BC


Maureen Tyner was born and raised in Pittsburgh Pennsylvania home of Heinz ketchup and inclement weather. She relocated to Phoenix Arizona in 2013 to work for Dr. Liz Cruz Partners in Digestive Health. Maureen attended Carlow University in Pittsburgh and finished her Bachelor’s of Science in Nursing in 2009.

Since becoming a nurse, Maureen has worked in Trauma Intensive Care, Neuro-Trauma Intensive Care, Brain Trauma research and as a certified Sexual Assault Nurse Examiner. Seeking to further her education and desiring to provide comprehensive care to her patients, Maureen went back to school and completed her Master’s of Science in Nursing with a Family Nurse Practitioner certificate in 2013.

She has a strong love of education and served as adjunct faculty at Carlow University. Maureen is board certified by the American Academy of Nurse Practitioners (AANP). In May 2017, she received her Doctor of Nursing from Arizona State University.  Maureen is married and has a daughter and spends her free time hiking, bagpiping, reading and enjoying the Arizona sun.

Katrina Olivas – Back-Office Medical Assistant

Katrina Olivas was born and raised in Phoenix Arizona. She attended International Institute of the America’s in 2008 to get her Medical Assistant degree. Katrina comes to Digestive Healthcare after working two years in an OB/GYN office and a year with a vascular / cosmetic surgeon. She has two beautiful daughters whom she adores. Katrina loves doing arts and crafts, scrap booking, watching movies and the news, and being outdoors.

Yuridia Arreola – Wellness and Back-Office Support


Yuridia (Yuri) Arreola was born in San Jose, CA and raised in Colorado. She moved to Arizona when she was ten years old. Yuri started in the medical field five years ago working in a chiropractic office. She attended Gateway Community College to become a certified Health Unit Coordinator. She is currently attending EMCC pursuing a career in medical administration and justice administration. God, faith and her family are the most important things in her life. Yuri has three sisters and two brothers and is the proud aunt to eight children.

Teresa Ortega – Receptionist


Teresa Ortega was born in Bronx New York, raised in New Jersey and has been blessed with the opportunity to travel and live in many places, including California, North Carolina, Florida, Caribbeans and now Arizona. Before joining Digestive Healthcare Associates as a Receptionist, she spent five years working with adults with special needs and disabilities. She has two sons who hold the key to her heart. Her two hobbies are her boys and photography. She loves to be around people – putting smiles on their faces and laughter in their hearts.

Ray Rodriguez – Scheduler / Referral Coordinator


Raymond (Ray) Rodriguez was born and raised in Tolleson, Arizona. Ray started his career in the medical field in 2009.  He graduated from Trendsetters CNA Academy as a Certified Nursing Assistant and Medication Technician.  He said “I do” to his best friend, on April 11, 2014.  He enjoys the company of his family and friends and his only wish is to one day explore Europe and the Hawaiian Islands. Ray enjoys participating and celebrating his Mexican Catholic traditions. Ray has always believed that the impossible is possible and his only hero is God.

Elizabeth Cruz Sr. – Back Office Support


Elizabeth Cruz was born in Fajardo, Puerto Rico, but was raised in Southern California. She moved to Arizona in 2007 to help Dr. Cruz start Digestive Healthcare Associates. In 2009 she returned home to Orlando, Florida where she’s lived since 1978. Elizabeth continues to contribute any way she can to the office. She has held many positions in her career; including 33 years with the Southern California Conference and the Florida Conference of Seventh Day Adventist. Her strong administrative, accounting, translation and customer service skills are always put to good use. In her spare time, Elizabeth is very involved with her family, church and community service projects. She loves spending time with her mother, her three daughters and many grandchildren.

Denise Mata – Procedure Scheduler

Denise Mata was born and raised in Phoenix, Arizona. She finished school to be a medical assistant in 2012 and has been in the medical field ever since. She loves to spend time with her three daughters and fiancé. Their favorite place to go is Dutch Bros. – her favorite is the Double RainBro black tea, it’s her go to drink! She really enjoys Sundays with her family, going to church and then having lunch. Her favorite restaurant is Oregano’s Pizza Bistro, she loves the Pablo Picasso salad. She also enjoys volunteering at her daughters school and watching her play soccer.

Alyssa Ontiveros – Back-Office Medical Assistant / Support

Alyssa was born and raised in Phoenix, Arizona. She is currently a nursing student at Grand Canyon University with a target graduation date of 2018. Alyssa has worked in hospitals since she was 16 years old. Her experience ranges from working in a hospital Emergency Room to working in a physical therapy office. In her spare time she rescues pitbulls, makes eclectic beaded jewelry, and loves attending car shows. She calls herself a “Speed Enthusiast” with regard to cars and trucks.

Tina Nunziato – Certified Holistic Nutrition Consultant


Tina Nunziato graduated from the Arizona State University College of Business Honors Program in 1996 with a Bachelor of Science in Marketing. After graduation Ms. Nunziato took a job as a Marketing Analyst for a local telecommunications vendor, now Lucent Technologies. She quickly moved out of market research and into business development as a Marketing Specialist where she worked on various new product and joint venture initiatives.

In late 1999, during the dot-com boom, Ms. Nunziato moved to San Francisco to start a web-based software company. Focused on the park and recreation market, the company went through many strategy iterations before it found its niche. In her role as COO and eventually CEO, Ms. Nunziato experienced all facets of business from raising capital and product design to selling, training and supporting customers.

In May of 2003, subsequent to selling her company to one of the industry competitors, Ms. Nunziato came back to her roots here in the valley. She accepted a position as the Director of Marketing with Carefx Corporation a healthcare software company in Scottsdale.
In 2007 Ms. Nunziato decided to try her hand in medicine when she started Dr. Liz Cruz Partners in Digestive Health with her life and business partner Dr. Liz Cruz. Ms. Nunziato and Dr. Cruz decided to take medicine one step further by offering a wellness program through their office. In conjunction with and to support this business Ms. Nunziato went back to school to receive her Certificate in Holistic Nutrition in 2010. Since then both businesses have been growing as they continue to help patients year after year with their digestive diseases, sluggishness and weight gain.

It is the passion of both Ms. Nunziato and Dr. Cruz to get the digestive wellness message to as many people as possible as fast as possible so to help heal a nation.

Our Amazing Team

Dr. Liz Cruz is devoted to your health for you and your loved ones.

After years of offering her digestive wellness knowledge, products and services to her patients and seeing amazing results time and again, Dr. Liz Cruz didn't want to stop there. "This information and these tools need to be shared with everyone now more than ever! It's never too late to change how you feel."– Liz Cruz M.D.

Dr. Liz Cruz loves to educate and help others adapt a healthy lifestyle that fits their needs.
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