The Johns Hopkins Hospital where he chairs the hospital's Nutrition Advisory Committee. He is an internist, gastroenterologist, and nutritionist. Dr. Mullin is nationally and internationally renowned for his work in integrative gastroenterology and nutrition. Mullin has accumulated over 30 years of clinical experience in the field of integrative gastroenterology and earned his master’s degree in nutrition while in practice. In 2009 he was named by the American Dietetic Association as an honorary member. Dr. Mullin has authored/edited several books in nutrition. He has been interviewed on radio and television and has contributed to many stories in print and electronic media.