Mark Hyman is a physician and best-selling author known for his work in functional medicine. He focuses on treating the root causes of chronic diseases rather than just the symptoms. Hyman has written several books, including Food: What the Heck Should I Eat?, which emphasizes the importance of nutrition in health. In addition to his writing, Hyman is the founder of the UltraWellness Center and serves as the director of the Cleveland Clinic Center for Functional Medicine. He is a prominent speaker and advocate for dietary changes to improve overall health and well-being, often promoting a whole-foods, plant-based diet.