METHODS: A total of 87 patients with IBS-D were selected in the Jinling Hospital between July 2011 and December 2013. Using a randomized, controlled trial, the efficacy of pectin for IBS-D was prospectively evaluated. Subjects were randomly assigned to receive 24 g pectin powder/d (n=46) or a placebo (n=41). Before and after 6 weeks of treatment, colonic microflora was examined by real-time PCR and compared between groups. Changes in stool frequency and form (Bristol stool scale), composite score of symptoms (Likert scale) and QOL scores (IBS-QOL questionnaire) were also monitored. Peripheral blood sample from patients with IBS-D was obtained to estimate the cytokines level, which was compared with that obtained from a group of age- and sex-matched healthy volunteers (n=20).

RESULTS: Those patients randomized to pectin experienced a greater reduction in composite symptom scores and Bristol stool scale scores, as well as significant improvement in QOL scores (P<0.05). The pectin acted as prebiotics and significantly enhanced faecal bifidobacteria and decreased total Clostridium sp (P<0.05). At baseline, patients with IBS-D demonstrated an abnormal IL-10/IL-12 ratio, which was normalized by pectin feeding alone (P<0.01). Placebo did not exert these effects on the aforementioned parameters after treatment. No significant adverse effects were reported during the study.

CONCLUSIONS: Pectin acts as a prebiotic in specifically stimulating gut bifidobacteria in IBS-D patients and is effective in alleviating clinical symptoms, balancing colonic microflora and relieving systemic inflammation. In view of its ability to re-establish a healthy gut ecosystem, pectin has the potential of being a therapeutic agent in IBS-D.