Presented herein are methods and compositions for treating congenital diarrheal disorders (CDD). Methods comprise administering to a patient in need thereof, an effective amount of a proanthocyanidin polymer composition from C. lechleri, preferably crofelemer. Administration of the proanthocyanidin polymer composition addresses the secretory diarrhea and symptoms associated therewith caused by the CDD and can improve nutritional status, electrolyte balance, hydration, growth and development of the patient.