Impact of a probiotic product on bowel habits and microbial profile in participants with functional constipation: A randomized controlled trial

Objective To investigate the clinical efficacy of a multi-strain probiotic product on bowel habits and microbial profile in participants with functional constipation. Methods This was a randomized, double-blind, placebo-controlled and parallel-arm study. Altogether 94 otherwise healthy adults aged 18 to 65 years with symptoms of functional constipation were randomized as part of the intention-to-treat population. The participants received a placebo or the probiotic product (1.5 x 10(10) CFU/day), consisting of Lactobacillus acidophilus DDS-1, Bifidobacterium animalis subsp. lactis UABla-12, Bifidobacterium longum UABl-14 and Bifidobacterium bifidum UABb-10 over 4 weeks. Outcomes included the patient assessment of constipation-symptom (PAC-SYM) questionnaire, stool frequency and consistency, and microbial profile. Results There were no significant between-group differences in the PAC-SYM score, despite significant within-group differences (P < 0.001) over the study period. The probiotic group showed a faster normalization of stool frequency and consistency, with most participants achieving a normalized profile after 1 week. Fecal samples of the probiotic group exhibited higher relative abundance of Ruminococcaceae (P = 0.0047), including the Ruminococcus genus, and lower relative abundance of Erysipelotrichaceae (P = 0.0172) at end-point compared with baseline. Placebo group samples showed similar abundance profiles over the study, with the exception of Clostridiaceae, which was lower at the study end-point (P = 0.0033). Among treated participants, all four probiotic strains were significantly more abundant after the intervention. Conclusions No significant differences were observed in symptomology, with both groups showing a more than 20% improvement. However, the probiotic helped modulate bowel function earlier than the placebo, with a corresponding shift to a more fibrolytic microbiota.