Meet the Team

Dr. Brett Wisniewski has been practicing natural medicine for nearly 15 years and serves as the full-time Clinic Director and clinical consultant at Gateway Natural Medicine. He holds a Master’s degree in Molecular Cell Biology and is a Diplomate of both the American Board of Chiropractic Internists (DABCI) and the American Clinical Board of Nutrition (DACBN).

Dr. Brett’s clinical expertise centers on immunology, autoimmune disease, infectious disease, and cancer. He has also collaborated with some of the leading natural medicine companies, helping to formulate unique and effective blends of botanicals and vitamins. In addition, he has played a key role in customizing laboratory approaches designed to uncover the root causes of patients’ conditions, complaints, and symptoms. Recognized nationally as a lecturer, Dr. Brett is known for pushing the boundaries of diagnostics and advancing the field of natural medicine. He is deeply committed to listening to his patients’ stories and finding the “missing puzzle piece” that can change the course of their health journey.

Outside the clinic, Dr. Brett enjoys the quiet moments of early mornings with a strong cup of coffee and tackling hands-on construction projects—often inspired by the never-ending “honey-do list.”

After spending more than 20 years in the skincare industry, I’ve had the privilege of helping clients feel confident, cared for, and truly at home in their skin. My career has been shaped by a love for connection, a respect for the craft, and a commitment to delivering results with a personal touch. Over the years, I’ve watched trends come and go, techniques evolve, and the industry transform — but one thing has always stayed the same: my passion for supporting people in feeling their best.

As our business has continued to grow, I realized my next chapter would be behind the scenes, building systems, supporting the team, and keeping everything running smoothly. While I’ve officially retired from hands-on skincare, I haven’t stepped away from the heart of the work. Today, I pour my experience, intuition, and industry knowledge into the backend of our business, ensuring that every part of the client journey reflects the same level of care and intention I brought to the treatment room.

This shift allows me to focus on what I love most — nurturing the foundation of our brand, creating a seamless experience for our clients, and supporting the team so they can shine. Though I may no longer be treating skin directly, my passion for skincare, service, and elevating others continues to guide everything I do. I’m proud to continue growing our business from behind the scenes and to help shape its future with the same heart that has guided me for the past two decades.

In my spare time you will find me reading on my Kindle (last year I finished 160+ books), working out, going for long walks and bike rides with my husband, perusing antique shops and vintage stores on the weekends.

Dr. Christine Hafer has been in family practice for nearly 20 years. She earned her Doctor of Chiropractic degree from Palmer College of Chiropractic in 2008 after completing dual Bachelor’s degrees in Neuroscience and Psychology. She went on to achieve her CACCP certification in 2016 and is currently advancing her training through the Diplomate of the American Board of Chiropractic Internists (DABCI) program.

Her clinical passions include gut health, natural hormone balance, autoimmunity, hypermobility and connective tissue disorders, and pediatric care. As both a practitioner and a mom, Dr. Christine’s journey into functional medicine was deeply personal—sparked by her own postpartum health challenges despite decades of living a natural lifestyle. That experience fuels her commitment to helping moms restore their health and, in turn, improve the well-being of their entire families.

Outside the office, Dr. Christine is a wife and busy mom of three daughters. She enjoys walking her dog, strength training, and cheering on her beloved Detroit sports teams. Most days, though, you’ll find her with an iced coffee in hand, driving her girls to dance, music, and sports practices.

Dr. Zaideman has been practicing since 2012 and is the owner of North Florida Spine and Wellness in Tallahassee, FL. He obtained his Bachelor of Arts degree at Florida State University and then went on to obtain his Doctorate of Chiropractic Medicine at Palmer College of Chiropractic. He is a Certified Functional Medicine Practitioner and also a Fellow of the International Board of Functional Neurology in Childhood Neurodevelopmental Disorders. He also has completed over 300 hours towards his American Clinical Board of Nutrition Diplomate (DACBN) and is currently enrolled in the Chiropractic Internist Diplomate (DABCI).

Dr. Zaideman has a special clinical interest in Autism, ADHD, Dyslexia, and other childhood developmental disorders as well as anxiety, depression, adult ADHD, TBI, balance disorders and cognitive longevity. He focuses his treatment on the interaction between physiology and neurology for a holistic mind and body-approach.

Dr. Jackson McKeehan was born and raised in Colorado, growing up in the Falcon area and attending Pine Creek High School. From there, he earned my Bachelor of Science in Biology at Midland University in Fremont, Nebraska, where I also played collegiate basketball.

His passion for health and human performance led him to pursue a Doctor of Chiropractic degree at Cleveland University–Kansas City (CUKC). During that time, he began training with the DABCI program (Diplomate of the American Board of Chiropractic Internists). He has had the privilege of learning from outstanding instructors and shadowing many clinics gleaning the best of the best protocols and therapies.

Dr. Jackson is also certified in acupuncture and brings a well rounded approach to our clinic. He also sees patients at our Colorado Springs location.

“At Gateway Natural Medicine, I believe healthcare should be personal, root-cause focused, and natural. Too often, patients are given quick fixes that overlook the underlying issue — my mission is to change that. If you’re seeking a natural, patient-centered approach to healthcare that focuses on long-term healing rather than temporary relief — you’ve come to the right place. Let’s begin your journey toward balance, restoration, and lasting health.”

Ashley Engler has been practicing Acupuncture since 2005 after graduating from Southwest Acupuncture College in Boulder, CO. She is licensed both by the National Acupuncture Association and the State of Colorado. Ashley has extensive training in motor point acupuncture for musculoskeletal and spinal issues as well as additional training in women’s health issues and cosmetic acupuncture. In addition to Acupuncture, Ashley utilizes a wide variety of techniques including therapeutic injection therapy, cupping, ear seeds, shockwave therapy, deep tissue laser therapy and pediatric acupressure techniques.

Her clinic concentrations are: Musculoskeletal pain, spinal-related issues, women’s health concerns, IVF support, pregnancy-related issues, anxiety/stress, and digestive support.

Outside the clinic, Ashley loves spending quality time with her husband and two sons. She also loves running outside, practicing yoga, paddle-boarding and frequently getting lost in a really great book.

Katie Martin is a family nurse practitioner who has been practicing as an FNP since 2021. Prior to that, she worked as a registered nurse for six years, primarily on a medical-surgical unit, where she developed a strong foundation in patient-centered care. She earned her Bachelor of Science in Nursing from Elmhurst College and graduated from the University of Northern Colorado with her Family Nurse Practitioner degree.

Katie currently works full time as a trauma and acute care surgery nurse practitioner, a role she values for the opportunity to care for patients across the continuum of their medical journey. She enjoys building meaningful relationships and believes that truly listening to each patient’s story is essential to thoughtful, effective care.

Drawn to natural medicine, Katie values a whole-person approach that blends evidence-based care with long-term wellness and prevention, including regenerative medicine options. She is passionate about patient education and takes the time to explain medical concepts in a clear, understandable way so patients feel empowered to participate in their own health.

Originally from a small town in northwest Illinois, Katie appreciates the sense of connection in close-knit communities and finds practicing in a small town especially meaningful. Outside the clinic, she enjoys running, hiking, reading, and spending time with her family and two dogs.

Carleen was born and raised in northern Colorado. She graduated aesthetics school at The White Magnolia Advanced Skin Institute in July 2022. She has always been passionate about encouraging women to be free in their own skin and feel confident and comfortable with the beauty they’ve been given, through personalized skin care treatments.

When Carleen was a little girl, she was always playing “spa” on her friends at sleepovers; even at a young age, she knew she wanted to help people feel their most radiant!

When she’s not working, you can expect to find her spending time outside with her daughter, baking in her kitchen, and swing dancing. She also enjoys going on adventurous taco tastings (recommendations welcome!)

Dr. Hayley Nick is a birth worker and movement-focused clinician who has been helping people feel stronger and more connected to their bodies since 2019. After earning her Doctor of Chiropractic degree from Palmer College of Chiropractic, she built her career on a simple philosophy: when people understand their bodies and receive care that honors their individual needs, they move with more ease, strength, and confidence.

While Dr. Hayley is Webster Certified and widely known for her work in prenatal and postpartum care, her expertise extends far beyond pregnancy. She has years of experience treating individuals of all ages, backgrounds, and activity levels. Her clinical style blends biomechanics, neuromuscular assessment, and strength-based rehabilitation to help patients reduce pain, improve function, and ultimately feel empowered in their movement.

As a perinatal chiropractor, Hayley brings advanced training in pelvic biomechanics, ligament dynamics, and optimal fetal positioning. She also specializes in pelvic floor strengthening and rehabilitation, helping women address dysfunction, rebuild foundational stability, and regain confidence in core and pelvic health during pregnancy, postpartum, and beyond. Her approach integrates breathwork, functional loading, and coordinated pelvic floor training to support both healing and long-term resilience.

Hayley is also certified in infant craniosacral therapy, allowing her to support newborns with gentle craniosacral assessment and care. Her work helps address feeding challenges, tension patterns, birth-related strains, and overall nervous system regulation.

Her work with athletes stems from a deep understanding of load, movement patterns, and the specific demands of sport. Whether she’s helping a powerlifter rebuild strength postpartum, a runner get back to pain-free miles, or a recreational athlete move without fear, she utilizes various techniques such as soft tissue mobilization, flexion-distraction, cupping, dry needling, and extremity adjusting.

Beyond hands-on care, Hayley is also a doula, bringing both emotional support and leadership experience to the communities she serves. Her dual background in chiropractic and birth work allows her to offer comprehensive, whole-person care grounded in clinical skill, compassion, and a deep respect for the body’s innate capacity.

Outside the clinic, Hayley has always lived an active, competitive life. She has competed in powerlifting within the USAPL since 2016 and in countless local CrossFit competitions, driven by her love of strength, movement, and pushing her own limits. Today, she balances training with life as a mom to her three-year-old daughter and spending time with her friends and family.

Avery was born and raised in Southern California and has always been inspired by the joy and connection that food brings—from both a holistic and a health-centered perspective. Even as a young girl, she intuitively understood the power of nourishing the body with real, whole foods to feel her best.

She graduated from the Institute for Integrative Nutrition (IIN) in August 2024. Before stepping fully into the wellness world, Avery studied Elementary Education and spent several years as a teacher. During that time, she found herself consistently answering questions from family, friends, and colleagues about nutrition and lifestyle. It soon became clear that her passion for supporting others through health and well-being was more than a side interest—it was her calling. Realizing it’s never too late to pivot, Avery returned to school to empower people in a new and deeply meaningful way.

When she’s not working with clients, you can almost always find her moving her body—biking, running, skiing, wakeboarding, or practicing yoga. And of course, she loves spending time in the kitchen, experimenting with delicious, nourishing recipes that she’s always excited to share.

Alex Miller is a dedicated Licensed Massage Therapist and Advanced Bodyworker who blends clinical expertise with a results-driven approach to movement longevity. Specializing in injury recovery, deep tissue trigger-point myofascial therapy, and sports massage, he works with athletes, fitness enthusiasts, weekend warriors, and anyone looking to break free from chronic pain and repetitive strain.

By integrating specialized therapies like cupping to increase circulation, scraping (IASTM) to release stubborn scar tissue, and targeted postural corrections, every session is customized to target the root cause of dysfunction rather than just mask symptoms. Whether you’re recovering from an injury, trying to improve your athletic performance, or looking to reverse the physical toll of a desk job, Alex’s goal is to help you restore fluid movement, eliminate pain, and rebuild structural balance.

A Colorado native who grew up in Berthoud, Alex graduated from the Colorado Institute of Massage Therapy in 2010 and brings over a decade of experience helping patients recover from work-related injuries and chronic pain. He’s also certified to train foam-rolling routines and postural strength exercises so you can keep up the work between sessions — foam-rolling is a great way to add pliability to the body’s soft tissue and improve muscle resiliency. When he’s not in the clinic, Alex loves to cook and BBQ, stay active, play disc golf, and spend time with his wife.

Dr. Sarah Swisher-Leatherman has enjoyed practicing in Florida for 23 years and is excited to return to the mountains. She is a graduate of the University of Oregon and Cleveland Chiropractic College and completed the 300+ hour Chiropractic Internist program.

She is passionate about living joyfully and positively, influencing and lifting up the women around her. Her clinical interests include nutrition focused weight loss, gut health, optimized perimenopausal hormone support and acute illness care. Outside of the office, she enjoys reading, walking in nature and giving Martha Stewart a run for her money in artful cooking.

Dr. Alexi is a dedicated chiropractor who graduated from Palmer College of Chiropractic in Florida in 2023. He is passionate about supporting long-term health and helping people reach their highest potential.

His clinical approach focuses on sports rehabilitation and full-body care, addressing both spinal and extremity conditions. He uses a combination of Diversified technique, dry needling, and targeted rehabilitation exercises to restore movement and function. Dr. Alexi takes the time to identify the root of each patient’s concerns and tailors care to their needs. He believes chiropractic goes beyond symptom relief—it’s about improving communication between the brain and body and supporting the body’s natural ability to heal.

His path into chiropractic developed gradually through personal experience and a growing alignment with a holistic philosophy of health. Through consistent chiropractic care, he realized he was feeling the best he had in years—an outcome he attributes directly to chiropractic. That experience continues to shape his patient-centered approach, emphasizing long-term results, consistency, and becoming resilient to stress.

A former college soccer player, Dr. Alexi understands the physical and mental demands of athletics and the importance of recovery firsthand. This experience gives him unique insight into movement, performance, and injury prevention. Known for his compassionate, detail-oriented approach, he works closely with each patient to help them reach their personal performance goals—whether in sports or daily life.

Outside the office, he enjoys hiking, working out, and traveling. Having spent most of his life in Florida, he is excited to explore Colorado’s natural beauty.