A series of N-of-1 trials will be used to determine the effectiveness of a specific carbohydrate diet (SCD) versus a modified SCD in patients in reducing symptoms and inflammatory burden at both the individual and population level. This is a four-year study. The study staff will recruit up to 60 patients across up to 21 sites in patients aged 7-18 with mild to moderate disease activity.

Inclusion Criteria:

• Diagnosis of Crohn's Disease (CD) or ulcerative colitis (UC) or Indeterminate colitis (IC)

• Age 7-18 years

• Enrolled in the ImproveCareNow (ICN2) registry

• Evidence of acute inflammation and/or elevated acute phase reactant as measured by Fecal calprotectin 1.5 times the upper limit of normal, Lactoferrin 1.5 times the upper limit of normal, CRP 1.15 times the upper limit of normal, or ESR 1.15 times the upper limit of normal (based on local reference ranges) obtained within 8 weeks of enrollment.

  • Potential participants who are close to meeting one of the acute inflammation and/or elevated acute phase reactant markers and who meet all other study criteria will be considered for study participation on a case by case basis by the investigative study team in consultation with the patient's primary gastroenterologist.

Exclusion Criteria:

Complex and Unstable IBD:

• Currently or within the past 9 months has had an abscess, fistula, stricturing CD, or ostomy

• Severe disease activity as measured by a short Pediatric Crohn's Disease Activity Index (SPCDAI) score of >45 or Pediatric Ulcerative Colitis Activity Index (PUCAI) score of >60 assessed within three weeks of enrollment

• Ever had history of full colectomy

• Hospitalization or surgery planned within 3 months

• Ongoing active gastrointestinal infection

• Severe Malnutrition (BMI less than 5th percentile)

• Recent medication changes including:

  • Thiopurines, natalizumab, or methotrexate started within 8 weeks prior to enrollment
  • Anti TNF (infliximab, adalimumab) started within 8 weeks prior to enrollment
  • Vedolizumab started within 16 weeks prior to enrollment
  • Increase in corticosteroids within 4 weeks of screening or have dose >20 mg prednisone or equivalent

Evidence of Other Complicating Medical Issues:

• Other serious medical conditions, such as neurological, liver, kidney, or systemic disease
• Serious psychological or psychiatric conditions such as eating disorders or self-harm
• Pregnancy
• Tobacco, alcohol, or illicit drug abuse

Inability to Complete the Protocol

• Non-English speaking participants

• On SCD or modified SCD anytime within 8 weeks of enrollment

  • If an otherwise eligible patient is on SCD or modified SCD within 8 weeks of enrollment but they are noncompliant per the determination of the patient's dietitian/primary gastroenterologist, then this patient is eligible to participant in the study.

• Participants on a vegan diet

• Lack of smart phone and data plan for participating caregiver

• Participating in another concurrent intervention study

We intend to provide access to the de-identified, HIPAA-compliant databases as required within a year after the study has been completed. Data plans, analysis plans, data dictionaries, study manuals and annotated case report forms will be made available, upon request, in a read-only format (PDF). Each dataset will be accompanied by appropriate documentation listing each variable, variable definition, decode values (if appropriate), an indication of the variable as a source collected or derived variable, and derivation algorithms for any derived values.

Datasets will be available as SAS, SAS transport, XML or CSV with labels. Other formats may be created if requested. All necessary security measures will be taken to ensure patient privacy and confidentiality, and details on how data may be used, including the use of de-identified data sets, will be included in the informed consent.

Within a year after study completion.