Probiotics Ameliorate Stool Consistency in Patients with Chronic Constipation: A Randomized, Double-Blind, Placebo-Controlled Study

Background/Aims The efficacy of probiotics for improving clinical symptoms, altering the fecal microbiota, and regulating serum immune cytokine levels was investigated in patients with irritable bowel syndrome-constipation (IBS-C) or functional constipation (FC). Methods A randomized, double-blind, placebo-controlled trial was conducted at Kyung Hee University Hospital between October 2016 and February 2017. Consecutive 18–75-year-old patients with diagnosis of IBS-C or FC (based on Rome IV criteria) consumed probiotics (3.0 × 10 8 CFU/g Streptococcus thermophilus MG510 and 1.0 × 10 8 CFU/g Lactobacillus plantarum LRCC5193) or a placebo daily for 4 weeks (weeks 1–4) and were followed up for a 4-week washout period without intervention (weeks 5–8). The primary outcomes of the study were Bristol Stool Form Scale and Complete Spontaneous Bowel Movements (CSBM). Efficacy was assessed by per protocol. Results Stool consistency measured by the Bristol Stool Form Scale was significantly better in the probiotic group ( n = 88) than in the placebo group ( n = 83) at 4 and 8 weeks (3.7 ± 1.1 vs. 3.1 ± 1.1 at 8 weeks, P = 0.002). No significant difference was found in CSBM. The quality of life was significantly better in the probiotic group than in the placebo group at 4 weeks ( P = 0.044) and 8 weeks ( P = 0.049). The relative abundance of L. plantarum among the fecal microbiomes was significantly greater in the probiotic group than in the placebo group at 4 weeks ( P = 0.029). However, the levels of other microbiomes and of serum cytokines (IL-10/IL-12 ratio and TNF-α) did not differ significantly between the two groups. Conclusions Probiotics significantly ameliorated stool consistency in patients with chronic constipation. In addition, the beneficial effect of L. plantarum on stool consistency remained after the probiotic supplementation was discontinued. The mechanism whereby probiotics benefit patients with chronic constipation should be clarified in further studies.