High- Fiber/ Low-fat Diet for Prevention of Recurrent Clostridioides Difficile Infection in Oncology

This is a randomized study. A total of 124 individuals with cancer 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 foods with 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.

• Diet Intervention (Other): The dietary fiber intake target will be 19 g/d for ages 9-18 and females age 19 and older and 23g/d for males age 19 and older.

Primary outcomes

• Number of Participants With Recurrent C Difficile Infection [6 weeks]: Clinical diagnosis of recurrent C. difficile

Secondary outcomes

• C. Difficile Toxins A and B [6 weeks]: Quantify toxins in stool using "Separate detection of C. difficile toxins A and B" kit (tgc Biomics)
• Fecal Microbiome [6 weeks]: Characterize the microbiome in fecal samples as using 16S rRNA targeted and shotgun metagenomic sequencing

Sex: All, ages: 9 Years to any

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.

Participant flow

Outcome results

• Number of Participants With Recurrent C Difficile Infection (Primary), Number, number of participants: Diet Intervention 1; no Diet Intervention 1
• C. Difficile Toxins A and B (Secondary)
• Fecal Microbiome (Secondary)

Adverse events

Time frame: from enrollment until end of intervention, up to 6 weeks

Serious adverse events by term

Other adverse events by term

Limitations and caveats: We did not recruit a sufficient number of study participants to assess our primary outcome of whether the frequency of recurrent C. difficile infection. was different between the study arms

• Study Protocol and Statistical Analysis Plan (PDF, 2025-10-10)
• Informed Consent Form (PDF, 2025-10-30)

• Catherine Lozupone, Principal investigator, University of Colorado, Denver

NIH grants: P30CA046934, U01AI150589