When Makenzie was 18 months old, she suffered a serious global brain injury after choking on a cracker. After five and a half weeks in the pediatric intensive care unit and intensive rehabilitation, she was released with a feeding tube in her stomach and a prescription for a hydrolysate formula called Peptamen Jr. For 11 months Mackenzie would throw up after every feeding. Her mother, Pam, took Makenzie for allergy tests, which revealed...