Our Team

Our Team

Dr. William M. Kleber,
D.C., D.A.B.C.I.

Dr. Kleber is a Board Certified Chiropractic Internist. His interest in internal medicine began when he came to believe that his patients were suffering from more than just subluxations, but serious internal disorders continually exacerbating the subluxations. His desire to learn more about these issues stemmed from his dedication to improve not only their health but the quality of their life with natural medicine. Dr. Kleber has built a successful practice in Berthoud, Colorado, providing alternative options to those who have exhausted the traditional field of medicine with no success.

He earned his Diplomate Degree from the American Board of Chiropractic Internists and has been practicing for nine years as an internist with more than 27 years as a chiropractor. He continues to balance his patient care with chiropractic techniques and resolution of internal disorders.

Dr. Kleber began his career in New York before settling in the beautiful foothills of the Rocky Mountains with his wife, Karen, and their four children.


Dr. Brett Wisniewski,

B.s., D.C., D.A.B.C.I., D.A.C.B.N.

Dr. Brett Wisniewski was born and raised in New Jersey. He attended Monmouth University where he received a Bachelors of Science degree in Biology with concentrated studies in Chemistry. Since, he has always gravitated towards the study of the human body and natural health. Dr. Wisniewski moved his family to Florida to further his studies at Palmer College Chiropractic where he graduated Cum Laude, with a Doctor of Chiropractic Degree.

Dr. Brett Wisniewski has worked with many of the industry’s leading nutraceutical companies, consulting and formulating nutritional supplements. He travels the country, educating both the medical and  alternative health care fields on natural treatments for the illnesses that plague our country. He has studied under some of the pioneers in the natural health industry and with thousands of hours invested into post-graduate studies in nutrition, he considers himself a lifelong learner.

Dr. Wisniewski has seen patients bounced around in the traditional medical model with little to no results or answers. He believes finding the fundamental cause can cure most diseases. Dr. Brett Wisniewski has extensive knowledge in nutrition, sports performance, metabolic weight loss, mitochondrial dysfunction and autoimmune disease.  He currently holds a Diplomate from the American Board of Clinical Nutrition and the American Board of Chiropractic Internists. Dr. Brett is pursuing a masters degree in immunology and molecular cell biology.  He enjoys pushing the envelope of healthcare to achieve better results, Naturally!

“I feel, I owe it to my patients to never stop learning so I can provide them with the proper level of healthcare that they deserve.” –Dr. Brett Wisniewski



Igor Zielinski, LAc

Igor Zeilinski earned his Master of Acupuncture and Oriental Medicine degree from Emperor’s College of Oriental Medicine in Santa Monica, California. He was certified as a Diplomat in Acupuncture and Traditional Chinese Medicine by the National Certification Commission for Acupuncture and Oriental Medicine in October 2008. This included Clean Needle Technique and Chinese Herbology. He was certified by the Acupuncture Board of California in October 2007. Prior to moving to California in 2003, he was an MD in Warsaw, Poland.


Igor’s training includes adjunctive therapies such as moxibustion, tuina, acupressure, cupping, auriculotherapy, and dietary and lifestyle recommendations. He has been a registered and licensed acupuncturist in Colorado since 2009 and a licensed acupuncturist in California since 2007. When he is not commuting to Berthoud, Igor splits the week at his own acupuncture clinic in downtown Denver, Colorado. Avicenna Acupuncture

“As a new person to acupuncture, I didn’t know what to expect. I guess “wow” would explain how I feel. After the first few treatments, I was feeling pain relief. Now, after today, I have no pain in my arm. Thad, you are interesting and very informative. I like the way you explain everything you’re going to do and what you are doing it for. You’ve helped my pain and helped me to relax in my hectic life. Thanks!” Ginny D


Front Office/Back Office

Kelly Wisniewski,
Office Manager

Kelly has been with our office since 2014 and maintains an efficient work flow throughout the entire office.  She is responsible for scheduling, billing and general management of Gateway Natural Medicine.  You can always count on her to be on top of things and greet you with a smile.


Lab and Patient Care

Racheal Piccoli,
MA/Back Office

Racheal has both a degree in Medical Assisting and Phlebotomy. She is the friendly face that assists the Doctor by getting your vital signs, performing ultra sound and other modalities, collecting samples for labs and scheduling your report of findings with the Doctor. She is also responsible for maintaining all policies and procedures for the back office.