Evaluation of Serum-Derived Bovine Immunoglobulin Protein Isolate in Subjects with Diarrhea-Predominant Irritable Bowel Syndrome

BACKGROUND: There is increased interest in combining nutritional modalities with pharmacological therapies for managing patients with diarrhea-predominant IBS (IBS-D). AIM: A randomized, double-blind, placebo-controlled study to evaluate the impact of oral serum-derived bovine immunoglobulin/protein isolate (SBI) on gastrointestinal symptom scores and quality of life (QoL) in subjects with IBS-D. METHODS: Study subjects previously diagnosed with IBS-D according to ROME II criteria were recruited from London, Ontario, Canada and assigned to receive 5 g/day SBI, 10 g/day SBI, or placebo for 6 weeks. Daily symptom frequency and severity scores and a modified IBS-36 questionnaire assessed the impact of nutritional intervention. Laboratory assessments were performed at screening and end of treatment (EOT) to evaluate safety. Within-group comparisons of changes in number of days per week with symptoms and symptom severity were conducted on the per-protocol population of subjects using a t-test. RESULTS: Subjects who received SBI at 10 g/day (N = 15) had statistically significant within-group reductions in abdominal pain (p < 0.01), loose stools (p < 0.01), bloating (p < 0.05), flatulence (p < 0.01), urgency (p < 0.05) and any symptom (p < 0.01) at EOT vs. baseline. Subjects receiving 5 g/day of SBI (N = 15) realized statistically significant within-group reductions in days with flatulence (p < 0.035), incomplete evacuation (p < 0.05), and any symptom (p < 0.01). There were no significant changes in QoL scores or in hematology or clinical chemistry among treatment groups. CONCLUSIONS: This pilot study showed that nutritional therapy with either 10 g/day or 5 g/day of SBI in 30 patients was well tolerated and resulted in statistically significant within group improvements in both symptom days and in daily symptom scores in subjects with IBS-D. Additional studies are underway with larger numbers of subjects to validate these findings.