Dr. Jay Luthar, MD, DipABLM, and Dr. Julia Loewenthal, MD have been named 2026 Castle Connolly Top Doctors, marking the second consecutive year they have received this honor. Only 7 percent of the nation's licensed physicians are selected annually 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. The practice is grounded in the belief that the most powerful medicine begins with deep, sustained relationships and strategic life-wide health stewardship. Unlike traditional volume-driven practices, at Lutanen Health each doctor cares for no more than 150 patients. It is the only academically affiliated primary care practice in Boston where longevity science is woven into everyday care.
Dr. Luthar stated, "The Castle Connolly recognition affirms what I believe matters most in medicine: time, trust, and partnership. 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 life span to preserve vigor and delay decline rather than simply react to illness.
Both Drs. Luthar and Loewenthal are fellowship trained in integrative medicine, bringing mind-body science and holistic approaches to lifestyle optimization and wellness to their patients. Their newly designed 3,000 square foot healing space in the heart of Back Bay includes a state-of-the-art human performance laboratory. Lutanen Health evaluates and treats a wide range of primary conditions with particular 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. The practice incorporates advanced diagnostic technologies and evidence-informed procedures, including 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 to ensure continuity and high-level integrative care. 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 both 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 serves 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. Castle Connolly publishes its Top Doctors list at castleconnolly.com and in various print and online partner publications. Nominations are open to all board-certified MDs, DOs, and DPMs. The Castle Connolly team chooses honorees based on nominee criteria that includes their medical education, training, hospital appointments, and disciplinary histories. Doctors do not and cannot pay to be selected as a Castle Connolly Top Doctor.
