The overall goal of the study is to investigate the dietary differences between children with well-controlled inflammatory bowel disease (IBD) and those with active disease by using targeted food metabolomics. The utilization of the application of targeted metabolomics allows for the investigation of specific components of foods and their effects in IBD and inflammation, which may inform future dietary recommendations for IBD patients.

The investigators overall hypothesis is that higher intake of animal origin foods lead to higher concentrations of TMAO and its precursors (TMA, choline and carnitine), which causes gut microbiota dysbiosis, ultimately resulting in elevated inflammatory markers (systemic and/or fecal) in pediatric inflammatory bowel disease (IBD).

The two primary aims include:

Aim 1: Examine the relationship between IBD activity, dietary patterns, and diet-derived potential biomarkers in serum and urine.

Aim 2: Investigate the association between IBD activity, dietary patterns, gut microbiome, and diet-derived potential biomarkers in stool.

Investigators will also explore the integrated relationship between disease activity, diet, gut microbiome, diet-derived potential biomarkers, and inflammatory markers.

Investigators will recruit 100 subjects with known IBD of > 6 months duration. Subjects will be asked to complete dietary questionnaires, and provide stool, urine, and blood samples.

Inclusion Criteria:

• Male and Female
• Established IBD diagnosis (both well-controlled and active disease) for > 6 months
• Followed by the Children's Hospital Colorado (CHCO) IBD Center
• Ages 8-18 years

Exclusion Criteria:

• Vegan diet
• Exclusive enteral nutrition (EEN) currently or within 2 weeks of enrollment
• History of full colectomy
• Ongoing active gastrointestinal infection
• Severe malnutrition (BMI less than 5th percentile)
• Presence of ostomy
• Recent medication changes

Patients with established IBD diagnosis (both well-controlled and active disease) for > 6 months