Improving Irritable Bowel Syndrome (IBS) Symptoms and Quality of Life with Quebracho and Chestnut Tannin-Based Supplementation: A Single-Centre, Randomised, Double-Blind, Placebo-Controlled Clinical Trial

Background/Objectives: Irritable Bowel Syndrome (IBS) is a disorder of the gut-brain axis for which the gastroenterologist is most often consulted. Gastrointestinal symptoms and decreased quality of life lead to a considerable burden of disease. The exact causes of IBS are not well understood, and no standard therapy has been established. The primary outcome of the study focused on the improvements of the IBS symptoms assessed through the validated questionnaire IBS-Severity Scoring System (IBS-SSS). Similarly, secondary outcomes geared towards the improvement of the quality of life (IBS-Quality of Life (IBS-QoL) and the Gastrointestinal Quality of Life Index (GIQLI)) and specific IBS symptoms (bloating, abdominal distension, feeling of heaviness, abdominal pain, and flatulence), were assessed through self-administered questionnaires. Intestinal habits (consistency and frequency of depositions) through subject stratification into diarrhoea (IBS-D), constipation (IBS-C), mixed type (IBS-M), as well as the treatment tolerability were also evaluated. Methods: A randomised, placebo-controlled, double-blind, clinical trial was conducted on 156 enrolled IBS patients (79 female and 77 male), aged 18–70 years, randomised (1:1 allocation ratio) to receive either two capsules per day of the food supplement (containing 480 mg of a complex of tannin extracts) or a placebo for 56 days. Linear random intercept mixed models (LMM) were used to analyse all experimental variables Results: Supplementation resulted in a significant improvement (p < 0.05) in the primary outcome IBSS score, with respect to the placebo group, changing the IBS condition going from mild (242.3 ± 89.8) to moderate (148.1 ± 60.6). Similarly, all indicators concerning quality of life, and specific intestinal symptoms resulted in a significant improvement (p < 0.05). Furthermore, the tannin-based treatment showed the ability to modulate the response to different symptomatology such as diarrhoea and constipation, without side effects being reported. Conclusions: The use of a supplement based on chestnut and quebracho tannins presents great application potential in the management of IBS-related disorders, with the peculiarity of resolving opposite symptoms, such as diarrhoea and constipation, indiscriminately.