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Dr. Mark Holthouse MD is the Chief Medical Officer for Functional Medicine Of Idaho and FMI Center For Optimal Health. Dr. Holthouse is only seeing patients through FMI Center For Optimal Health. To inquire about being seen by Dr. Holthouse, follow this link to the New Client Inquiry form, here.
Areas of Expertise:
• Expertise in both Men’s & Women’s Hormone Management and Bioidentical Hormone Replacement Therapy: pellets etc.
• Expertise in thyroid and adrenal gland imbalances
• Expertise in reversing pre-diabetes, diabetic medicine, metabolic syndrome
• Optimizing body composition: lean muscle and belly fat removal / Intermittent Fasting
• Expert in managing cholesterol, cardiac, and blood pressure from a holistic perspective
• Expertise in anti-aging and cellular senescence management
• Expertise in environmental medicine: heavy metals, mold diseases, mast cell activation syndromes
• Expertise in holistic approaches to autoimmune and gut health
• General Functional Medicine
Michael Sermon is the Medical Director of Functional Medicine of Idaho since 2023. He earned his Bachelor’s Degree in Human Movement Science at Utah State University. He then continued his education at Saint Francis University earning his Master of Physician Assistant Science. While working in family practice, urgent care, and emergency medicine in the rural areas of Texas and Oregon, Michael discovered that lifestyle modification and root-cause medicine is the key to disease prevention and healing.
After experiencing the effectiveness of root-cause medicine in his own life, and the lives of his patients and family, it became clear to Michael that the functional medicine model is key to lifelong health. He believes that patients should be highly involved with their own health care decisions, with guidance and expertise from the FMI team. Michael integrates traditional primary care with functional medicine in order to achieve preventative and restorative care for patients. He is currently working on functional medicine certification.
Michael enjoys hiking, biking, ice hockey, and many other sports. He spends his free time with his wife and children, enjoying the small things life has to offer.
Areas of Expertise:
Amy Ray is board certified by the American Nurse Credentialing Center as a Family Nurse Practitioner. Amy has over 20 years of healthcare experience and is passionate about seeking out the root causes of chronic “dis-ease” and empowering her patients to reach and maintain a state of optimal wellness. She has her undergrad in Nutrition Science from UC Davis and her Master’s degree in Nursing from MGH Institute of Health Professions in Boston, MA.
She first started looking in to functional medicine after many years of being disillusioned with allopathic medicine when her chronically ill patients rarely ever felt better with conventional treatment. She became fully committed to functional medicine after her father was diagnosed with stage 3 chronic kidney disease and was told he would be “monitored and then treated when it got worse- and it would get worse.” Luckily, he was not satisfied with that answer and came to her for help and guidance using her new found functional approach. He is at is healthiest now, and she has never looked back.
Amy has extensive experience in metabolic syndrome, insulin resistance, hormone imbalance, gut health, headaches, and autoimmune issues. She truly believes that food is medicine and that lifestyle changes are foundational for reversing chronic “dis-ease.” She believes our bodies are incredibly smart and protective and seeks to partner with her patients to find ways for their unique bodies to find the wellness and balance they once knew. She is an IFM Board Certified Functional Medicine Provider.
Outside of the office, Amy enjoys fitness, volunteering, gardening, traveling and all things outdoors. She and her husband moved to the area in hopes of enjoying all the wonderful outdoor opportunities Idaho has to offer.
Specialties include:
Elizabeth Hingley is an accomplished Family Nurse Practitioner, who earned her MSN degree from Georgetown University in Washington, DC in 2013. Her passion for patient care and dedication to her profession led her to pursue additional certifications. In 2022, she received her IFMCP through IFM.org, and she has been a Certified Diabetes and Education Specialist since 2011. Elizabeth has gained valuable experience in urgent care and endocrine management, specializing in diabetes, thyroid, testosterone, and weight management. She noticed that even with traditional medicine, some patients still experienced persistent symptoms, which led her to explore alternative therapies and focus on lifestyle management to address the underlying causes. Elizabeth is committed to patient education and empowering them to take ownership of their health, working with them as partners on their health journey. In addition to her passion for health and wellness, Elizabeth enjoys traveling with her loved ones, trail running, hiking, and exploring the great outdoors.
Areas of Expertise:
Diabetes
Thyroid
Weight Concerns
Janessa Tenney is a board certified Physician Assistant who offers in-person and telemedicine primary and functional care for adults at the Functional Medicine of Idaho Meridian Wellness Center.
Early in her career as a Physician Assistant, Janessa was introduced to functional medicine while working at a private practice in Monterey, California, where she witnessed first-hand how patient outcomes could be drastically improved if the patient was properly educated about their lifestyle and nutrition choices. She began studying functional medicine and started to implement its principles into her conventional medical practice. Janessa joined the Functional Medicine of Idaho team in 2021, and now combines her love for patient education with her passion for functional medicine in order to change patients’ lives every day.
Janessa earned her Bachelor of Science in Public Health from Brigham Young University – Idaho, and her Master of Medical Sciences in Physician Assistant Studies from Salus University. She is currently working towards her certification with The Institute for Functional Medicine.
Outside of the clinic, Janessa enjoys hiking, paddle boarding, kayaking, spending time with her friends and family, watching movies, and trying new food.
Karen Callagy received her Bachelor’s degree in Kinesiology from Pennsylvania State University in 1997. After working in Physical Therapy, as a PTA for several years, she went on to obtain her M.S. in Physician Assistant Studies at Arizona School of Health Sciences in 2005. She began her PA career in Family Medicine, eventually transitioning to Urgent care, as well as a brief stint in Oncology.
In all these settings, she began to realize that prescribing medications was not enough to make patients better and in many cases only perpetuated the problem. In her personal life, she was dealing with family members with autoimmune diseases that conventional medicine could not help, because diet was never addressed. After discovering the Institute of Functional Medicine in 2014, there was no turning back. Not only has she helped her own family but innumerable patients with the help of IFM. She continues to work towards her IFM certification, specializing in thyroid and gut health.
Karen firmly believes in “mind, body and spirit” and that each of these aspects must in balance for her patients to achieve their maximum health potential. She immensely enjoys going on the journey to wellness with her patients and believes it “takes a village” to accomplish this, ie. Nutrition staff, life coaching, and in some cases counseling.
In her personal life, she enjoys outdoor activities with her husband and 3 children, on the mountain where they reside, with their bunnies and Bernese Mountain Dog.
Areas of Expertise:
Julie is a board certified Family Nurse Practitioner with over 12 years of experience, providing acute and primary care for patients of all ages.
Julie was born and raised in Boise. She completed her bachelors of nursing at Boise State University. In pursuit of higher education Julie completed her masters and doctorate at George Washington University. Her doctorate is in palliative care, focusing on providing a well rounded approach to patient care. Her goal is to provide the highest quality of life for all her patients, to work in a collaborative relationship and support individual goals.
She is continuing her education through The Institute For Functional Medicine with the goal of obtaining her Functional Medicine Provider certification.
In her free time, Julie spends time with her family including her husband Joe and their two sons. They enjoy camping, hiking, and skiing.
Shelby L. Stoddard, FNP-C, MS, CCT, FAAO, believes that uncovering the “WHY” behind symptoms is crucial for promoting optimal health. As a dedicated Nurse Practitioner with a diverse healthcare background, she finds fulfillment in offering hope that feeling good again is attainable. Shelby prefers to implement small changes that lead to consistent, long-term improvements. With experience in adult cardiology, the ISU medical residency program, rural family medicine in Island Park, and Nutritional/Functional Medicine, she has refined her skills over the past decade to deliver comprehensive care.
Shelby’s journey began in Pennsylvania, where she started as a CNA in 1993. She graduated from the Licensed Practical Vocational School in 1994 and earned her Bachelor’s degree in nursing from Millersville University in 2001. In 2002, she made Idaho her home and later graduated from Idaho State University’s Family Medicine Nurse Practitioner program. She is board-certified by the American Association of Nurse Practitioners and has guest lectured at Boise State University Nursing Department.
Shelby has received training in Functional Medicine practices from esteemed professionals such as Frank Shallenberger, MD, Robert Rowen, MD, John Lyftgoft, MD, Jeff Harris, ND, Scott Nelson, DC/Master acupuncturist, Tom Clarke, DC, American College for Advancement in Medicine (ACAM), and International Foundation for Nutritional Health. She has served as a supervising provider/lead in the FDA Clinical Research Study for the use of UVLRX Intravenous therapy in chronic illness and fatigue, as well as the study Investigator for the OPTIMA-G pain study using compounded pain cream as alternatives to opioid prescriptions for chronic pain syndromes.
Shelby understands that the integration of mind, brain, nerves, and immune systems is essential for overall well-being. She recognizes that sickness and disease can result from trauma, exposure to poisons/toxins, and pathologic insults, exacerbated by negative influences leading to further cellular damage. Inspired by Dr. Masaru Emoto’s water experiment, which showed the impact of words on water crystals, Shelby believes in the healing power of embracing various healing practices. She prides herself on being open-minded and providing tools for change.
Shelby’s passion for helping patients extends to her interests in mitochondrial dysfunction/optimization, chronic illnesses like Lyme disease, viruses, and parasites, immune system optimization/dysfunction, chronic and acute fatigue, oxygen/ozone therapies, prolozone injections for joints (especially knees), neural therapy, neurofeedback, thyroid management, weight loss/maintenance management, hypertension, endothelial dysfunction, stem cells, peptides, hormone optimization, anti-aging aesthetics, neuromuscular optimization, and intravenous nutrient support for cellular health. Her compassionate approach and dedication to patient care make her a valuable asset to the Functional Medicine of Idaho team!
Outside of her professional life, Shelby finds joy and relaxation in nature. Whether she’s fishing for bass, steelhead, and sturgeon on the river, hiking, snowshoeing, snowmobiling, mountain biking, or competing in NRL22 matches, she embraces the great outdoors.
Jacqueline Griffin, NP is a dedicated Nurse Practitioner based in St. Augustine, Florida, with additional licensure in Arizona, Idaho, and Washington. Her lifelong interest in natural living was inspired by her grandparents, who cultivated their own vegetables long before the farm-to-table movement gained popularity. The premature loss of her father in 2006 propelled her to investigate the shortcomings of the medical system, leading her to a career in healthcare. She honed her skills as a heart nurse at prestigious institutions such as Yale, Penn Medicine, and Johns Hopkins — completing her graduate studies at Chamberlain University and subsequently worked as a Nurse Practitioner in Internal Medicine and Family Practice, accumulating two years in internal medicine and several more in primary care.
Her extensive bedside nursing experience also includes ten years in Cardio-Thoracic Surgery, a year in Oncology, and seven years in health and wellness/nutrition coaching. In 2018, Jacqueline’s path led her to become a patient of Dr. Stephan Cabral. Inspired by his approach, she began training with him in Functional and Integrative Medicine two years later. Jacqueline is board certified in Family Medicine, Ortho-Molecular Medicine, and Bioregulatory Medicine, with additional training in Indian Medicine and the science of Ayurveda. She prides herself on integrating the best of all forms of medicine to uncover the root causes of her patients’ health imbalances. Jacqueline’s focus of interest is also on assisting patients in reversing trauma, PTSD, and various mental health conditions.
Jacqueline’s professional journey was paralleled by her personal battle with chronic illness, enduring 15 years of misdiagnoses and suffering from chronic gut issues, autoimmune conditions, mold toxicity, and chronic infections. With over 17 years of training in health, nutrition, trauma therapy, fitness, and both modern and alternative medicine, Jacqueline combines evidence-based research with a holistic approach to address the root causes of health imbalances. Her goal is to help her patients feel their best and achieve longevity.
Recognizing that medicine is not one-size-fits-all, she tailors her care to fit each individual’s unique needs, utilizing conventional modalities and testing when appropriate and diving deeper when necessary. Through Functional and Integrative Medicine, along with faith and patience, she found healing. Now, she channels her own experience and knowledge to help her patients find their own paths to wellness.
Christa Inzer Castillo is a board certified Physician Assistant, with 14 years of experience in family practice, who offers primary and acute care for adults and children. She loves the opportunity to get to know entire families and develop relationships with her patients. While trained in western medicine she has long infused a whole person and natural approaches to achieve best patient outcomes.
Personal experience, specifically a mother who has responded poorly to the traditional western medical approach, but used whole body approaches to find answers inspired Christa to begin the process of understanding root cause medicine. The desire to help answer “why” is this going on in the body and “how” to help the body heal has become a passion. The process of teasing out each person’s unique puzzle is fascinating and rewarding, especially when you start to see health restored.
Christa grew up in the Treasure Valley, graduated from Meridian High School, earned her Bachelor of Science in Biology from the College of Idaho. In 2008 she earned her Master of Science in Physician Assistant Studies and Masters of Public Health from Touro University in Vallejo, California.
Outside of the clinic, Christa enjoys spending time with her husband and 3 children. You can find them outside working on numerous projects with chickens, goats, rabbits, dogs, cats, and gardening, or hiking and exploring the great state of Idaho. She also loves to serve in her church and squeeze in a swim.
Kaitlin Cooley is a board certified Family Nurse Practitioner who offers primary and acute care for adults and children. She has experience working with all ages of patients from neonatal to geriatric care.
As a Boise native, Kaitlin enjoyed a collegiate softball career in front of her friends and family at The College of Idaho. Kaitlin graduated from the college with a bachelors degree in Health Sciences. She later attended Idaho State University and obtained her nursing degree. After working as a registered nurse in the hospital, Kaitlin discovered she wanted to help patients optimize their health in the primary care setting by building foundational wellness. As a result, Kaitlin applied to Northwest Nazarene University and later graduated with honors with her Family Nurse Practitioner degree.
Kaitlin is passionate about providing quality care and helping patients feel their best. She practices an individualized, patient-centered, and science-based approach when meeting with patients and believes the best outcomes are met when patient and provider work in collaboration. She is continuing her education through The Institute For Functional Medicine with the goal of obtaining her Functional Medicine Provider certification.
Kaitlin is married to her husband, Matt, and has two sons. They enjoy spending time outside golfing, hiking, and running around with the kids.
Nick Garver is a dedicated physician assistant with a passion for preventative medicine and root cause care. He earned his degree from A.T. Still University in Mesa, Arizona, and brings a wealth of experience to Functional Medicine of Idaho, combining his expertise with a commitment to helping patients achieve optimal health.
Nick witnessed firsthand the limitations of a reactive healthcare system and was inspired to pursue a better way of practicing medicine—one that focuses on addressing the root causes of illness rather than merely treating symptoms. He specializes in cardio-metabolic health, men’s health, and general wellness, providing comprehensive care that empowers patients to thrive.
Outside of his work, Nick enjoys an active and fulfilling life with his wife and two young children. A true outdoorsman, he spends his free time fishing, golfing, exercising, and making cherished memories with his family. Nick’s heart-centered approach and love for the outdoors reflect his belief in living a balanced and health-focused life.
Jessica Bennett graduated with a Bachelors of Science in Nursing from the University of Vermont in 2003. After practicing as a nurse for ten years, she felt an unwavering desire to continue her education and pursue an advanced practice degree as a Certified Nurse Midwife. Graduating with honors from Frontier Nursing University in 2014, Jessica set out as a Certified Nurse Midwife and has never looked back.
Over the past seven years, Jessica has provided women’s health primary care, with a particular emphasis on hormone imbalance, including thyroid conditions, PCOS, infertility, sexual pain, and hormone replacement therapy for pre-menopausal and post-menopausal women. She is also experienced in full-scope well woman/primary care, including natural childbirth, birth control consultations, family planning, IUD and Nexplanon insertions and removals, GYN annual exams, problem visits, medication management, thyroid issues, hormone balancing, gut health, natural approach to managing mood disorders, and diet and exercise management for weight loss.
Her approach to women’s healthcare is focused on prevention, total body wellness, and patient education. With a true passion for health, wellness, and empowering women, she is immensely grateful to have the opportunity to pursue her passions every day.
Tammy Hadfield, MSN, WHNP-BC, ABAAHP has been caring for women for over thirty years. She began
her career as an Associate’s Degree prepared Registered Nurse in 1991 at the University of Utah Medical
Center. She quickly found a passion in caring for mothers, babies and their families while working in high
risk obstetrics and volunteering as a rape and domestic violence victim’s advocate.
Tammy completed her Bachelor’s Degree with Honors in 1995 from Weber State University. After which
she joined the United States Air Force as a commissioned medical officer. Tammy was a labor and delivery nurse, lactation specialist, neonatal resuscitation instructor, and perinatal grief counselor during
her early military years. She was awarded an Armed Forces scholarship to attend graduate school to complete her Master’s in Nursing from University of Utah. She became a board certified Women’s Health Nurse Practitioner in 2001. Her first duty assignment as a nurse practitioner was in Anchorage, Alaska, where she was awarded the Pacific Air Force Advanced Practice Nurse of the Year award, and
served the GYN mobility troop commander. Tammy achieved numerous awards and medals, including the prestigious Meritious Service Medal and attained the rank of Major prior to her separation.
In 2004, Tammy moved to Idaho and quickly grew her practice specializing in bio-identical hormone
replacement for men and women, gynecological health, and age management medicine. She is proud to
have been the first board certified anti-aging diplomat in Idaho from the American Academy of Anti-Aging Medicine. In 2009, she founded and opened an independent medical practice Embrace Wellness.
She has written for Healthy Idaho and has been featured on KTVB channel 7 in a variety health related
segments.
After 15 years of solo practice, Tammy is pleased to join the FMI team. She specializes in providing hormone management for women from puberty through menopause, gynecological care, birth control options including intrauterine devices (IUDs) and implants (Nexplanon), abnormal pap smear management and colposcopy, sexual wellness, lichen sclerosus treatment, pelvic pain evaluation, PCOS management, and thyroid management. She not only offers medical treatment options but also advice on functional nutrition and supplemental therapies.
Tammy has been married since 1991 to Dalon, who is a VAMC nurse. They have raised two amazing daughters, and are proud grandparents. Tammy loves spending her time outside of work traveling, gardening, cooking, and enjoying time with her family.
Dr. Mario Brus obtained his medical and pediatric specialty training at Loma Linda University in Southern California. He is a board-certified pediatrician and maintains his Fellow of the American Academy of Pediatrics (FAAP) designation with his ongoing commitment to lifelong learning and advocacy for children.
His current emphasis is pediatric functional medicine, which aims to find underlying causation for pediatric chronic conditions. He addresses the root cause of these conditions with appropriate laboratory testing, genetic testing, and by emphasizing lifestyle and nutrition changes, as well as appropriate nutritional supplementation. This functional approach to pediatrics allows Dr. Brus to partner in the care of your child by listening to your concerns and making your child’s health his primary focus.
He believes in a conservative use of drugs and an aggressive encouragement of lifestyle and dietary changes that strongly impact body and brain function. Overall, his goal is to fix health issues at their source.
Aaron Dykstra is a board certified Family Nurse Practitioner with a Doctor of Nursing Practice degree. He offers pediatric primary care, including well-child checks and acute visits, in the Pediatric Department of the Functional Medicine of Idaho Meridian Wellness Center.
Functional and alternative therapies were a part of Aaron’s life from a young age, and he has implemented these principles into his conventional medicine practice throughout his career. Aaron has more than 8 years of experience in a variety of medical disciplines, including pediatrics, obstetrics, mental health, and nutrition. He has practiced in rural health clinics in California and Oregon. For the last 5 years, Aaron has had a passion for working with children and implementing positive change through the family unit. Aaron joined the Functional Medicine of Idaho Pediatric Team in 2021. His enthusiasm for educating children and parents about living a healthy lifestyle allows him to provide preventative and acute care for infants, children, and adolescents.
Aaron obtained his Bachelor of Science in Nursing at Brigham Young University. He earned both his Master’s of Science in Nursing and Doctor of Nursing Practice through the University of Arizona. He has obtained a Family Herbalist and Family Nutritionist certifications through The School of Natural Healing by Dr. Christopher. He is currently working towards his certification with The Institute for Functional Medicine.
Outside of work, you will find Aaron spending time with his wife and 5 kids, mountain biking, running, or camping in the backyard. Aaron is a big fan of Master Chef and enjoys cooking.
Olivia Mangeac is a certified Physician Assistant who offers pediatric primary care, including well child checks and acute visits, in the Functional Medicine of Idaho Pediatric Department.
Olivia began her career working in Urgent Care at St. Alphonsus, where she practiced as a Physician Assistant for 5 years. Throughout her time in Urgent Care, she became interested in root cause medicine and chronic illness prevention. Wanting to provide a wider scope of care for her patients by diving deeper and addressing more than surface-level symptoms, Olivia began studying functional medicine. She joined the Functional Medicine of Idaho Pediatric Team in 2021. Her passion for taking a proactive approach to healthcare allows her to provide preventative and acute care for infants, children, and adolescents.
Olivia earned her Bachelor of Science in Biology from Northwest Nazarene University, and her Master of Medical Science from Arcadia University.
In her spare time, Olivia enjoys snowboarding, hiking, backpacking, and spending time with her husband and daughter.
Lois Payne is an internationally credentialed coach through the International Coaching Federation, a certified Rapid Transformational Therapy hypnotherapist, and a graduate of the Functional Medicine Coaching Academy. She has created workshops, retreats, lifestyle programs, and worked individually with clients over the past 6 years to move them forward towards the results they want.
She is passionate about her work in maximizing the Functional Medicine process by supporting patients as they work to achieve their health goals. It is also her aim for them to see other aspects of their lives improve along the way.
In her spare time, and as a new transplant to Idaho, she finds herself drawn to explore the beautiful greenbelt and trails along the Boise River and to connect with the wonderful people here. She is curious about everything, and will try to read anything suggested to her.
Marianne Green earned her Bachelor’s Degree in Nutrition and Dietetics in 2018 from the University of Alabama. She then continued her education through Daemen College’s Dietetic Internship to earn her license as a Registered Dietitian. Prior to her career as a Dietitian, she was a Social Worker and obtained her Master’s Degree in Social Work from Eastern Washington University.
Marianne has experience in eating disorders, functional medicine, women and children, and overall wellness. She helps patients optimize their health while providing individual functional medicine nutrition based counseling. Marianne serves patients with all health concerns through a preventative lens, as patients aim to achieve optimal health in each stage of life.
In her free time, Marianne enjoys watching and playing sports with friends and family. She and her husband also spend time gardening and cycling.
Hailie Kuttler is a registered dietitian (RD) and board certified Integrative and Functional Nutrition Practitioner (IFNCP). She provides personalized nutrition counseling utilizing a ‘food first’ approach in preventing and reversing chronic health conditions. Hailie recognizes that sustainable change rarely happens overnight, and strives to support and empower her clients on their path to better health.
For many clients that she has had the privilege of partnering with, food has become a source of confusion, guilt, and stress. She is passionate about supporting people as they learn new ways of nourishing their bodies to achieve their best health.
Hailie, a Boise native, holds a Bachelor’s degree in Nutrition and Dietetics from the esteemed University of Idaho. Her expertise lies in empowering clients to enhance their digestive health, achieve a harmonious weight balance, and optimize their metabolic well-being by employing the principles of functional nutrition. With a particular focus on digestive conditions like IBS and SIBO, Hailie exhibits a profound passion for understanding and nurturing the intricate world of the gut microbiome and overall gut health. To further augment her knowledge and skills in functional nutrition, she pursued advanced education through Integrative and Functional Nutrition Academy.
In her free time, you can find Hailie experimenting with new recipes; biking on the greenbelt; backpacking in the Sawtooths; hiking with her two labs; or curled up with a cup of tea.
