The primary objective of the study is to determine whether dietary intervention to increase fiber and decrease fat reduces C. difficile infection recurrence in a cohort of oncology patients.

This is a randomized study. A total of 124 individuals with either acute leukemia or lymphoma and a first or second occurrence of C. difficile infection will be enrolled. Participants will be randomized to Arm 1 (Diet intervention) or Arm 2 (No diet intervention). Participants in Arm 1 will be assessed for food preferences and will be provided lists of high fiber and high saturated fats. Participants will be able to choose foods from the high fiber food lists and groceries will be provided once per week to support each participant's meal plan. Participants will be asked to limit foods on the high saturated fats list. Food consumption with a 24 hour recall and weight will be monitored and stool samples will be collected one time per week for 6 weeks. In Arm 2, participants will be asked to provide 24 hour food recall and stool samples. Individuals in both arms will be monitored for stool consistency and any antibiotics or chemotherapy drugs taken. Participation will last 6 weeks.

Inclusion Criteria:

• Diagnosis of a malignant neoplasm at the at Children's Hospital Colorado or the University of Colorado Hospital
• Diagnosis of first time or first recurrent CDI as defined by clinical criteria within the past 21 days
• Informed consent obtained and signed. For minors, the consent will be completed by a guardian and the study participant will sign the assent form. Only the consent form is required of adults.
• 9 years old or older
• 40th to 100th percentiles of saturated fat intake and below the 50th percentile for fiber intake based on a food frequency questionnaire.
• Ability to comply with study procedures for the entire length of the study.