Nearly a decade ago, a thin, soft-spoken twenty-something woman named Megan walked into my office and presented me with a meticulous hand-written file containing her gastrointestinal history. The file included descriptions of her initial diagnosis of Crohn’s disease as a teenager, the multiple operations she had endured to remove diseased parts of her bowels, and the array of symptoms she suffered with, including nausea, a dozen bowel movements a day, and a total reliance on nutrition obtained through her veins...