Dr. Jay Luthar, MD, DipABLM, and Dr. Julia Loewenthal, MD have been named 2026 Castle Connolly Top Doctors, marking the second year they have received this prestigious designation. Only 7 percent of the nation's licensed physicians are chosen each year as Castle Connolly Top Doctors for their specialties in their regions. Both physicians practice at Lutanen Health, a bespoke primary care and longevity practice in Boston's Back Bay.
Lutanen Health operates on the principle that the most powerful medicine begins with deep, sustained relationships and strategic life-wide health stewardship. Unlike traditional practices driven by volume, each doctor at Lutanen Health cares for no more than 150 patients. The practice is the only academically affiliated primary care practice in Boston where longevity science is woven into everyday care.
"The Castle Connolly recognition affirms what I believe matters most in medicine: time, trust, and partnership," said Dr. Luthar. "Dr. Loewenthal and I share the conviction that care should be uniquely designed for each individual patient. When you understand someone's biology, context, and goals over time, you can offer care that is not only more effective but deeply human."
At Lutanen Health, primary care becomes private health management, identifying risk long before symptoms emerge and allocating interventions across a lifespan to preserve vigor and delay decline. Drs. Luthar and Loewenthal are fellowship trained in integrative medicine, bringing mind-body science and holistic approaches to lifestyle optimization. Their newly designed 3,000 square foot healing space includes a state-of-the-art human performance laboratory.
The practice evaluates and treats a wide range of primary conditions, with a focus on metabolic health, cardiovascular risk reduction, cognitive preservation, and healthy aging. The clinical team specializes in managing complex internal medicine cases while addressing the unique needs of older patients, including frailty risk, medication optimization, and age-related vitality. Advanced diagnostic technologies include AI-guided plaque detection, multi-cancer early detection blood testing, VO₂ max testing, biological age tracking, advanced biomarker and genetic analysis, comprehensive fitness and mobility assessment, and structured sleep evaluation.
Practice amenities reflect its relationship-driven model: extended visits, same-day appointments, 24/7 physician access, individualized nutrition counseling, and for select patients, home visits. Complimentary valet parking is also available. Dr. Luthar completed his medical residency at Cambridge Hospital, a Harvard Internal Medicine Residency Site, and is board-certified in Internal Medicine, Integrative Medicine, and Lifestyle Medicine. Dr. Loewenthal completed her Internal Medicine residency at Brigham and Women's Hospital and her fellowship in Geriatric Medicine through the Harvard Multi-Campus Geriatrics Program. She is board-certified in Internal Medicine and Geriatric Medicine, and board eligible in Integrative Medicine. Both physicians maintain academic faculty roles at Harvard Medical School, where Dr. Luthar serves as an Instructor and Dr. Loewenthal as an Assistant Professor. Their work bridges clinical care, education, and research to advance the science of healthy aging.
Top Doctors are nominated by peer physicians and selected by the physician-led Castle Connolly research team. The full list is published at castleconnolly.com and in partner publications. Doctors do not and cannot pay to be selected.
