A single-blinded, randomised experimental study was conducted. Potential participants were screened based on the inclusion and exclusion criteria during telephone interviews. As the patients were their own controls, self-reported allergy was not an exclusion criterion as long as both interventions were carried out during unchanged allergic exposure.~Patients were then randomly allocated to one of two study arms: Referm® or thickened water (Thick-it ®, commercially available; Kent Precision Foods Group, Inc., Muscatine, IA, USA) as placebo. The patients underwent sigmoidoscopy with biopsies obtained from the distal colon at baseline and after 14 days of intervention with ReFerm® or placebo enema twice a day. The enema was administered rectally, in the left side position, and retained for as long as possible (at least 10 min) both in the left-sided and supine body position to activate retrograde peristalsis. To assess clinical improvement of symptoms, questionnaires were completed twice: before and after the intervention. During the 14 days of the intervention, the patients completed daily questionnaires. To improve compliance with the study intervention, the patients were given a check-up call by a principal investigator (OBe) twice per week during the intervention period.
Impaired intestinal permeability and microbial dysbiosis are important pathophysiological mechanisms underlying irritable bowel syndrome (IBS). ReFerm®, also called Profermin®, is a postbiotic product of oat gruel fermented with Lactobacillus plantarum 299v. In this experimental study, we investigated whether ReFerm® has a beneficial effect on the intestinal epithelial barrier function in patients with IBS.