Founder & medical director
Mark Su, MD, FAAFP
A board-certified family physician with more than twenty-three years of full-time patient care, a national leader in environmentally acquired illness, and the person who designs and signs off on every RootSeek Personalized Health Map.
His story
He built a practice around the patients medicine kept sending away.
Dr. Su has practiced on the North Shore of Massachusetts since 2003, first as a primary care physician and, from early on, as the doctor other doctors sent their hardest cases to. Patients arrived with fatigue that no test explained, pain without a cause, brain fog, reactions to foods and chemicals, and a folder of normal results. Over two decades that work narrowed into a specialty: chronic inflammation and the illnesses that hide behind it, including mold and water-damage exposure, Lyme and tick-borne disease, autoimmunity, long COVID, mast cell activation and immune deficiency.
In 2014 he founded Personal Care Physicians of Greater Newburyport so he could practice medicine the way he thinks it should be practiced: unhurried, personal, and honest about what is known and what is not. In 2021 he founded RootSeek so patients who could not get to his office could still get his thinking, with a full care team around them.
He is president of the International Society for Environmentally Acquired Illness, the professional body for clinicians who work with mold, water-damage and environmental illness, and he trains other clinicians in that field. He has been asked to serve as an expert in mold-related legal matters, sits on the medical advisory board of MedSystems, has authored peer-reviewed research and book chapters, and has presented more than twenty times at national and state conferences, including the ISEAI annual conference, the Vibrant Longevity Summit and CellCore’s clinical conferences.
Patients and colleagues describe him two ways, and both are true: a detailed diagnostician, and a healer more than a doctor. He is analytical and relational, sees the forest and the trees, and is proudest of having built family-owned practices where the person in front of him still comes first. He is a father of four and the husband of Jessica Lasky-Su, DSc, a Harvard researcher whose work and community have shaped his own.
Every week he hosts the Functional Medicine Reality Podcast, where you can hear how he thinks through a case before you ever book a call.
The care team
One team, one map, one plan.
You will not be handed off. Your physician, your clinician, your nurse and your coach all work from the same Personalized Health Map, and they talk to each other.
Clinicians
Board-certified physician associate with 24 years in practice: athletic training, orthopedics, then 14 years in emergency medicine, where she saw conventional care fall short for chronic and inflammatory illness. IFM-certified functional medicine practitioner focused on autoimmune conditions, gut health and hormone imbalance.
Board-certified family nurse practitioner trained through the Institute for Functional Medicine. A University of New Hampshire nursing graduate and former telemetry nurse, she is also trained in yoga, holistic stress management, health coaching and herbalism.
Bachelor’s in kinesiology and Master of Science in Physician Associate Studies from Northeastern University, with experience in primary care and emergency medicine. Focuses on gut health, nutrition and whole-person wellness.
Nursing & coaching
University of Massachusetts nursing graduate and certified yoga teacher. Former medical-surgical and telemetry nurse at Anna Jaques Hospital in Newburyport and a visiting nurse. Heidi runs your regular check-ins and keeps the plan moving between visits.
Bachelor of Science in Nursing from Indiana University and Certified Natural Health Professional, specializing in body balancing and biofeedback. Years of experience helping women with hormonal imbalance through nutrition and supportive group work.
Functional Diagnostic Nutrition Practitioner and integrative health coach with nutrition and hormone specialties from the Nutritional Coaching Institute, NASM certified, and a former professional snowboarder of twelve years. University of Utah graduate.
Operations
Over two decades in healthcare strategy and business management, and a personal history with Lyme disease. Jen runs strategy, operations, compliance and the day-to-day so the clinical team can focus on you.
Licensed phlebotomist with more than 30 years in traditional medicine, most recently at Tewksbury State Hospital. Robin manages scheduling, lab coordination across specialty laboratories, supplement orders, onboarding, superbills and portal messages. She is usually the first person you talk to, and the one who makes sure nothing falls through the cracks.
Portal messages get a reply. Nurse and coach check-ins are on the calendar, not on request. That is the level of support most virtual programs promise and few deliver.
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