This study aims to evaluate the impact of diet on the gut microbiome in adults with Clostridioides difficile infection (CDI). Eligible participants will be randomized and receive meals plus different types of health counseling. Counseling visits will be by phone or online videoconference (e.g. Zoom). Meals will be provided for two weeks and then participants will be asked to continue similar meals for 6 more weeks.

Participants will provide responses to questionnaires and multiple stool samples over the course of the study. The goal is to understand how different health factors might impact the risk of becoming infected again with C. difficile in the future.

Of note, this study will conceal the intervention details (type of diets) so that the control group does not increase their intake with the particular diet during the study. Participants in the control arm will be unblinded at the end of the study during a debrief with a member of the study team. At that time participants will be informed of diet being tested.

Inclusion Criteria:

• Provision of signed and dated informed consent form
• Stated willingness to comply with all study procedures and lifestyle considerations and availability for the duration of the study
• Non-recurrent non-fulminant CDI (laboratory-confirmed C. difficile infection without prior C. difficile infection within 3 months and no shock, hypotension, ileus, or megacolon)
• Currently receiving treatment or with plan to initiate treatment for CDI
• CDI treatment with standard regimen (fidaxomicin 200milligrams (mg) by mouth (PO) twice a day x 10-14 days or vancomycin 125mg PO 4 x a day (QID) x 10-14 days)
• No prior advanced therapy for C. difficile (i.e. prolonged antibiotic therapy, bezlotoxumab, fecal transplant, other microbial therapy)

Exclusion Criteria:

• Chemotherapy, immunotherapy, or transplant within 12 months
• Colon not in continuity (i.e. status post total colectomy or with current ileostomy)
• Medical comorbidities requiring specific fluid, sodium, or protein intake level outside range of prepared diet options
• Baseline diet with > 11grams fiber/1000 kilocalories
• Low sodium diet, vegan diet, gluten-free diet, Kosher diet or any other diet not able to be accommodated by the metabolic kitchen
• Allergies, food preferences, or other restrictions not able to be accommodated by the metabolic (note: lactose intolerance will not impact eligibility)
• Unwilling to stop probiotic supplements during the study period
• Current antibiotic therapy that will continue after CDI treatment has finished
• Hospitalized or in skilled nursing facility at time of CDI treatment conclusion
• Pregnancy or breast-feeding
• Unable to provide a stool sample of appropriate quality for further analysis (i.e. low volume, adulterated, delayed return, etc.)

The type of diet will be masked to the health counseling group.