Effect of administering a multi-species probiotic mixture on the changes in fecal microbiota and symptoms of irritable bowel syndrome: a randomized, double-blind, placebo-controlled trial

Abstract

We assessed the effect of multi-species probiotic mixture on the changes in fecal microbiota and irritable bowel syndrome (IBS) symptoms. Eighty-one IBS patients were randomly assigned to receive either probiotic mixture (n = 39; containing Lactobacillus acidophilus, L. rhamnosus, Bifidobacterium breve, B. actis, B. longum, and Streptococcus thermophilus) or placebo (n = 42) for 4 weeks. A questionnaire regarding general symptom relief was administered. The change in total symptom scores (sum of 10 IBS symptoms) and subtotal scores in 4 domains (pain, constipation, diarrhea, and bloating/gas) were evaluated. The change in fecal flora was determined by quantitative real-time PCR. The concentration of probiotic strains significantly increased after ingestion in probiotics group (B. bifidum, p = 0.043; B. lactis, p<0.001; L. acidophilus, p = 0.016; L. rhamnosus, p<0.001). The proportion of patients with adequate symptom relief was higher in probiotics group than in placebo group (74.4% vs 61.9%, p = 0.230). The decrease in total symptom score over time was not significantly different between the groups (p = 0.703). Among subtotal scores of 4 IBS symptom domains, the time effect was significantly different for diarrhea-symptom score between the groups (p = 0.017). A 4-week administration of multi-species probiotic mixture significantly increased the fecal concentration of most probiotic strains and improved diarrhea-symptom scores in IBS patients.

Keywords: diarrhea; fecal microbiota; irritable bowel syndrome; probiotics; treatment.

Fig. 1

A flow diagram illustrating the study design. *Questionnaire on stool form/frequency and VAS scores for 10 IBS symptoms. **Questionnaire on stool form/frequency, VAS scores for 10 IBS symptoms, and whether any relief in the general symptoms was achieved.

Fig. 2

The quantitative changes in the probiotics in the fecal sample before and after the study period. (a) Bifidobacterium bifidum, (b) B. lactis, (c) B. longum, (d) Lactobacillus acidophilus, (e) L. rhamnosus, (f) Streptococcus thermophilus; PLC-B, placebo group before the study period; PLC-A, placebo group after the study period; PRB-B, probiotics group before the study period; PRB-A, probiotics group after the study period; *p<0.05, **p<0.001.

Fig. 3

The quantitative changes in the levels of Bacteroidetes and Firmicutes in the fecal sample before and after study period. (a) Firmicutes, (b) Bacteroidetes, (c) Firmicutes/Bacteroidetes ratio; PLC-B, placebo group before the study period; PLC-A, placebo group after the study period; PRB-B, probiotics group before the study period; PRB-A, probiotics group after the study period.

Fig. 4

The change in stool form/frequency and total symptom score during the study period. (a) Stool form, (b) Stool frequency, (c) Total symptom score; Means and SE are shown. P values were calculated for time-group interactions by repeated-measures analysis of variance.

Fig. 5

The change of score in 4 IBS symptom domains during the study period. (a) Pain/discomfort score, (b) Constipation-relate symptom score, (c) Diarrhea-related symptom score, (d) Bloat/gas score; Means and SE are shown. P values were calculated for time-group interactions by repeated-measures analysis of variance.