IBS is the most common diagnosis in new patients in our pediatric gastroenterology clinic, accounting for 36 % of all new patients. Pediatric IBS patients always have a problem with defecation, characterized either as diarrhea predominant or constipation predominant. About one third of pediatric IBS subjects have d-IBS. There are no FDA approved treatments for children with d-IBS. There is evidence that diarrhea predominant irritable bowel syndrome d-IBS may be caused by a mild inflammation in the intestinal lining. Oral serum-derived bovine immunoglobulin protein isolate (SBI) is a medical food, believed to treat mild inflammation in the small intestine associated with some cases of d-IBS, especially those arising after acute gastroenteritis. It improved pain and diarrhea in adults with d-IBS. Our aim is to determine if SBI improves the number of spontaneous bowel movements in children with d-IBS.

The objectives of the study are to determine whether there is improvement in gastrointestinal symptoms (i.e., number of spontaneous bowel movements. abdominal pain, stool consistency, reduction in stool number, flatulence, urgency, incontinence), in laboratory parameters, and/or in psychosocial measures in subjects with d-IBS receiving 3 weeks of SBI.

This is a randomized, double-blind, placebo-controlled, weighted, pilot study evaluating effects of SBI (10 g per day), in children or adolescents with d-IBS.

The primary outcome will be change in the number of spontaneous bowel movements from the screening week compared to the final week. This information is gathered as part of the daily diary questions.

Secondary clinical outcome variables will include changes in abdominal pain, stool consistency, flatulence, urgency, and incontinence. Further clinical outcome variables will be change in number of spontaneous bowel movements during each treatment week compared to the screening week. Stool consistency will be assessed with the Bristol Stool Form Scale. Secondary laboratory outcome variables will include changes in stool calprotectin, stool lactoferrin, erythrocyte sedimentation rate, C-reactive protein, and platelet count from the screening week and final week. Secondary psychosocial outcomes will include data from Pediatric Quality of Life Inventory for Gastrointestinal Symptoms, and the Pediatric Functional Disability Index.

Inclusion Criteria:

1. Males and non-pregnant females between 8 years and 18 years at the time of consent.
2. Able to obtain parental or legal guardian informed consent from subjects as applicable.
3. d-IBS determined by ROME III criteria. A Rome III diagnosis consists of recurrent abdominal pain or discomfort at least 2days/week in the last 3 months prior to enrollment associated with two or more of the following10:

1. Improvement with defecation 2. Onset associated with a change in frequency of stool 3. Onset associated with a change in form (appearance) of stool.

Exclusion Criteria:

1. Children taking pharmacologic treatment for d-IBS will be excluded.
2. Children who are unable to articulate symptoms of IBS will be excluded.
3. Non-English speaking children will be excluded.
4. Children with known allergy or hypersensitivity to beef or any component of SBI.
5. Pregnancy.