OBJECTIVE. Meta-analyses have indicated effect of probiotics on irritable bowel syndrome (IBS). However, few long-term trials have been conducted and uncertainty remains as to effectiveness and long-term effect in a primary care setting. We aimed to investigate the effect of probiotics compared with placebo in the management of IBS in primary care during a 6-month treatment period and with a 6-month follow-up. MATERIAL AND METHODS. We randomized IBS patients fulfilling Rome III criteria to receive two capsules twice daily either containing placebo or a probiotic mixture of Lactobacillus paracasei ssp paracasei F19, Lactobacillus acidophilus La5 and Bifidobacterium Bb12 in an amount of 1.3 × 10(10) CFU per capsule. Primary endpoint was proportion of responders defined as patients reporting adequate relief (AR) at least 50% of the time in the 6-month treatment period. Secondary outcomes were proportions of patients reporting AR at different time points, and change in gastrointestinal symptoms and health-related quality of life (HrQOL) from baseline to 6 and 12 months. RESULTS. A total of 131 patients were included in this study. The proportion of responders in the treatment period was 52% (35/67) in the probiotic group versus 41% (26/64) in the placebo group, p = 0.18. Overall we found no difference between the groups in change in gastrointestinal symptoms after treatment. Patients improved in HrQOL, but with no statistically significant difference between the groups. CONCLUSION. During a 6-month treatment period, we were not able to detect a positive effect of probiotic when compared with placebo.
Trial registration: ClinicalTrials.gov NCT01151657.