Research project led by Bailey Hanna, MS, RDN - no affiliate links, ads or sponsored products.
A single randomized, double-blind, placebo-controlled trial investigated a 4-strain probiotic blend in an IBS population over 6 months, administered at a daily dose of 8 to 9 billion CFU. The study faced several methodological challenges, including a high rate of antibiotic use in the placebo group during the intervention, the use of non-validated symptom monitoring tools or measures not specific to IBS, and a small sample size that rendered the study underpowered to detect statistical significance for several outcomes. Attrition rates were also substantial.
Our independent analysis revealed no significant improvements in symptoms related to bowel habits, and no significant changes in stool frequency for IBS-C, IBS-D, and IBS-M subtypes. Distention and quality of life also showed no significant improvements. While the study authors reported beneficial effects for flatulence and abdominal pain, our analysis found these effects to be statistically non-significant due to the study being underpowered. We observed improvements in urgency and feelings of incomplete evacuation, categorizing them as improvements in diarrhea and constipation, respectively, but remain cautious about these findings due to the lack of significant improvements in bowel movement frequency across all subtypes.
The study did report improvements in total IBS symptom scores in the latter half of the study, which reached statistical significance, albeit with an effect size categorized as minimal.
Key Takeaway:
The beneficial effects of this probiotic were minimal at best and were confounded by methodological flaws in the study, as well as a high rate of antibiotic use in the placebo group. Moreover, benefits were inconsistent for urgency and bowel movement difficulty compared to the nonsignificant improvements in bowel movement frequency reported across all subtypes. While dosing information is provided below, we currently cannot recommend the use of this probiotic for IBS with confidence.
Trial Duration
Reference:
Kajander K, Hatakka K, Poussa T, et al. A probiotic mixture alleviates symptoms in irritable bowel syndrome patients: a controlled 6 month intervention. Aliment Pharmacol Ther 2005;22:387–94.
There is insufficient evidence demonstrating benefits for IBS with this probiotic. Therefore, we do not provide guidance on finding a commercial product containing this strain/blend.
This probiotic has low to moderate quality studies in IBS populations supporting it. View our evidence evaluation framework to learn how we assess the quality of studies.
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A probiotic mixture alleviates symptoms in irritable bowel syndrome patients: a controlled 6 month intervention
Aliment Pharmacol Ther 2005;22:387–94
ADULTS 20-65 years
In the probiotic group, nine patients (43%) experienced diarrhea at least once during the second half of the study, compared to four patients (24%) in the placebo group. No between-group statistical analysis was provided. There was no significant change in bowel movement frequency for the IBS-D group at months 4-6.
During the last three months of the study, the baseline-adjusted urgency score was 5.2 for the placebo group and 3.3 for the probiotic group, resulting in a treatment difference of -1.9 (95% CI: -3.5 to -0.3; P = 0.021). We calculated an effect size of 0.52 for the improvement in urgency score, placing it in our moderate beneficial range.
While we categorize this probiotic favorably for its benefits related to urgency, our confidence in its effectiveness for managing diarrhea is limited. This is due to the lack of significant improvement in bowel movement frequency in IBS-D participants and the higher incidence of single episodes of diarrhea in the probiotic group compared to the placebo group.
There was no significant change in bowel movement frequency in the IBS-C group. The treatment difference for the feeling of incomplete evacuation score was -2.1 points (95% CI: -4.0 to -0.1; P = 0.039).
We independently calculated an effect size of 0.47 for this parameter, placing it in our lowest effect size category. While we categorize the improvement in incomplete evacuation as a beneficial effect, our confidence in this probiotic’s benefits for constipation is limited due to the lack of significant change in bowel movement frequency in the IBS-C group.
A trend towards increased weekly stool frequency in the probiotic group was observed in the constipation and mixed subgroups during the last three months of the study. Although there were no significant differences between the treatment groups, an almost significant difference was noted in the mixed subgroup (12.2 vs. 10.2; p = 0.076).
During the last month of the study, the treatment difference in the baseline-adjusted symptom score (abdominal pain, distension, flatulence, borborygmi) was 7.7 points (95% CI: 13.9 to 1.6) when comparing the probiotic group with the placebo group (p = 0.015). This corresponds to a median reduction of 42% in the symptom score for the probiotic group versus a 6% reduction for the placebo group.
During the second half of the trial, the treatment difference in the total symptom score was 6.5 points (95% CI: 12.5 to 0.4) in favor of the probiotic group (p = 0.037). The total symptom score decreased from baseline in 76% of patients receiving probiotics and in 43% of those receiving placebo (p = 0.002). We independently calculated an effect size of 0.46 for the total symptom scores, placing this effect in our lowest beneficial effect size category.
From baseline to the second half of the study, 66% of the probiotic group experienced reduced abdominal pain compared to 43% in the placebo group, a difference reported as statistically significant (p=0.035). However, our independent analysis found this parameter to be statistically non-significant due to the study being underpowered.
There was no significant difference in distention compared to the placebo during the latter half of the study (p=0.221).
The study authors reported that during the second half of the trial, flatulence decreased in 68% of patients in the probiotic group and 40% of patients in the placebo group, which they stated was statistically significant (p = 0.011).
However, our independent analysis did not find this effect to be statistically significant, as the study lacked sufficient power to demonstrate significance for flatulence.
No data
At baseline, the mean quality of life score was slightly higher in the probiotic group compared to the placebo group, but the difference was not statistically significant (72 out of 100 vs. 64 out of 100 points; p=0.094). There was no change in the mean score at 3 months or 6 months in either group compared to baseline.
At baseline, the symptom of borborygmi was significantly less severe in the probiotic group compared to the placebo group. During the last half of the treatment, 61% of the probiotic group and 38% of the placebo group reported alleviation of borborygmi.
The between-group comparison was statistically significant in favor of the probiotic group (p=0.035). We calculated an effect size of 0.58 for this parameter, placing this beneficial effect in our moderate effect size range. However, the relevance of this change is unclear due to the uneven distribution of symptom severity at baseline
Antibiotic use during the intervention period was higher in the control group (50% vs. 27%, P = 0.032). Since antibiotics can alter the microbiota and affect IBS symptom severity, an analysis excluding all antibiotic-treated subjects was conducted.
In this subsample (probiotics n=30, placebo n=20), probiotics also appeared more effective in alleviating symptoms during the last three months of the study: the treatment difference was 8.3 points (95% CI: 17.3 to 0.4) in favor of the probiotic group compared to the placebo group (P = 0.062).
There was a trend towards milder symptoms in the probiotic group across all primary symptoms (abdominal pain, distension, flatulence, and borborygmi), though the differences were non-significant except for borborygmi.
The study used a symptom diary developed by the researchers, and Quality of Life (QoL) was measured by a RAND questionnaire, which included generic health questions and was not specific to IBS. Descriptive measures for secondary outcomes were not reported in the same detail as primary outcomes.
The study had substantial attrition, but only reported an overall number rather than attrition by independently assessed groups. The study was also not sufficiently powered to make several of the detected effects statistically significant.