This clinical trial aims to understand the feasibility of patients taking ketone body supplement beta-hydroxybutyrate (BHB) for 4 weeks with a confirmed diagnosis of Crohn's disease and starting new therapy for active disease.

The main questions it aims to answer are:

• BHB supplementation will be feasible and acceptable to patients.
• BHB supplementation will be associated with a reduction in systemic inflammation.
• BHB supplementation will be associated with a reduction in pro-inflammatory bacterial colonies.

Participants will:

• Take 3 capsules x 3 times per day for 4 weeks.
• Document food consumption using a 24-hour food recall questionnaire.
• Provide blood and fecal samples twice, at the beginning of the study and the 4-week mark.

Researchers will compare the group taking the ketone body supplement and the group not taking the supplement to see if the supplement provides relief of symptoms suffered from Crohn's disease.

A clinical trial designed to determine the feasibility of prebiotic supplementation with beta-hydroxybutyrate (BHB) in Crohn's patients in a prospective, open-label pilot trial and to assess the association between BHB supplementation and changes in the microbiome, inflammation, and markers of disease severity in Crohn's patients in a prospective pre-/post-study design.

Inclusion Criteria:

• Age ≥18 years of age
• Confirmed diagnosis of Crohn's disease
• Active disease defined as either a fecal calprotectin >250 µg/g or active disease on endoscopy within the prior 3 months
• Starting a new therapy defined as a biologic (anti-TNF, anti-integrin, IL-12/23, or IL-23) or small molecule therapy (JAK inhibitor, S1P receptor modulator)
• Willing to provide consent for participation.
• Managed at UT Digestive Health Clinic.

Exclusion Criteria:

• Any current or recent (within 4 weeks) use of BHB supplement
• Currently or recently (within 4 weeks) following a ketogenic diet
• Currently or recently (within 4 weeks) following an intermittent fasting diet
• Any recent antibiotic use (within 3 months)
• Recent infection with C. difficile (within 6 months)
• Current or recent (within 4 weeks) daily use of acid-suppressing therapy (proton pump inhibitor or H2 receptor blocker)
• Current or recent use (within four weeks) of non-dietary probiotic supplements
• Unwilling to provide signed consent

Eligible consenting patients will be randomized to either standard of care therapy (control) vs standard of care therapy plus BHB supplementation (intervention). BHB will be supplemented as a capsule taken orally three times daily for four weeks for those randomized to the intervention arm.