All patients are asked to complete two 7-day Food Diaries at baseline and end of radiotherapy treatment. All patients keep a daily record of stool characteristics and frequency using the Bristol Stool Chart. Patients also complete a short 1-page weekly-cost questionnaire to assess the economic impact of symptom management. Patients in arms I and II complete several additional questions regarding the costs (if any) of adhering to their fiber prescription and the palatability of the diet.