Effects of a (poly)phenol-rich supplement on anthropometric, biochemical, and inflammatory parameters in participants with morbid obesity: Study protocol for a randomised controlled trial.

Background: Morbid obesity (body mass index ≥40 kg/m2) represents a severe health risk and implies the need of urgent therapeutic action. (Poly)phenols may play a relevant role in the management of this disease modulating physiological and molecular pathways involved in energy metabolism and adiposity. The purpose of this double-blinded, placebo-controlled, randomised trial is to determine if (poly)phenol supplementation, in combination with a dietary intervention, can improve anthropometric and cardiometabolic parameters in participants with morbid obesity. Methods: Adults (n = 40) with morbid obesity, bariatric surgery candidates, will be recruited from the Bellvitge University Hospital, Spain, and randomly assigned (stratified by sex) to intervention (poly)phenol-rich supplement 1,200 mg/day + hypocaloric diet) or control group (placebo + hypocaloric diet) for 12 weeks. The primary outcome is body weight. Secondary outcomes are: other anthropometric markers and body composition measured through standardized methods and a bioimpedance analysis, cardiometabolic and inflammatory biomarkers, metabolic pathways, and gut microbiota diversity. Anthropometric parameters, dietary, physical activity and lifestyle questionnaires, blood pressure, and blood and urine samples will be collected at baseline, 6 weeks, and 12 weeks. Faecal samples will be collected at baseline and at 12 weeks. Informed consent of participants will be obtained before the start of the study. Discussion: The present study is expected to provide evidence on the effects of a combination of (poly)phenols on several well-established obesity and cardiometabolic markers, and to unravel possible underlying mechanisms by metabolomic analyses. Gut microbiota diversity will be considered as a potential future endpoint. The study will contribute to future strategies for prevention or treatment of obesity and related conditions.