This study evaluates whether the gut microbiome is involved in determining whether children with irritable bowel syndrome (IBS) develop worsening GI symptoms (e.g. pain) when given fructans (a sugar often found in wheat). Participants will both receive a diet with fructans and a diet without fructans.

Fructans (fructo-oligosaccharides) are a type of carbohydrate which can not be hydrolyzed by humans. It is commonly found in wheat in the American diet. After ingestion they arrive essentially intact into the colon where they are metabolized by the colonic microbiome. Fructan avoidance has been found to help decrease gastrointestinal symptoms (e.g. pain) in those with IBS.

However not all individuals with IBS have worsening symptoms when eating fructans in their diet. This study seeks to evaluate whether the microbiome is involved in determining whether an individual with IBS has worsening symptoms with fructan ingestion.

Following a one week baseline period, participants will be randomized in a double-blind cross-over fashion to either a 72 hour meal period with fructans or a 72 hour meal period with maltodextrin (placebo). A washout period of at least 10 days will occur in between. Symptoms will be captured using a stool and pain diary. Stool specimens and urine specimens will be obtained at baseline and during the dietary interventions. Breath hydrogen testing will be obtained during the dietary interventions.

Inclusion Criteria:

• Children ages 7-17 years
• Children with IBS will meet Rome III criteria per the Rome III questionnaire
• Healthy children will not have chronic conditions
• English speaking and able to read/write in English

Exclusion Criteria:

• Previous bowel surgery
• Documented gastrointestinal disorder (e.g. ulcerative colitis)
• Serious chronic medical condition (e.g. diabetes)
• Weight and/or height are greater than or less than 2 standard deviations for age
• Chronic conditions with GI symptoms (e.g. cystic fibrosis)
• Antibiotics within the past 3 months
• Pregnancy
• Autism spectrum disorder and/or significant developmental delay
• Mood disorders (e.g. major depression)
• Known post-infectious etiology