Dr. Marcus B. Callahan, M.D.

Dr. Marcus B. Callahan is a board-certified physician specializing in men’s health, hormonal balance, and natural performance solutions. With over 20 years of clinical experience, Dr. Callahan has helped thousands of men improve their vitality, energy, and confidence using safe, holistic approaches. A graduate of the University of Michigan Medical School, Dr. Callahan has spent the last decade researching plant-based ingredients that support cardiovascular function, blood flow, and sexual wellness — the core foundations of male vitality. His passion for non-invasive, natural remedies led him to collaborate with nutritionists and herbal scientists in formulating supplements like Boostaro.