Plant-Based Foods and (Poly)Phenol Supplementation in Gut Microbiota Modulation, Body Weight, and Cardiometabolic Risk

This single-blind, randomized controlled trial aims to evaluate the effects of increased dietary polyphenol intake-either through a healthy plant-based diet (PBD) or supplementation-on body weight and cardiometabolic risk factors in adults with overweight or obesity. A total of 99 participants (aged 25-45 years, BMI 25-35 kg/m²) with cardiovascular risk factors will be recruited from local health centers and randomly assigned (1:1:1) to one of three intervention groups for 12 weeks: (1) a healthy PBD rich in polyphenols, with supplemental apple, blueberries, hazelnuts, extra-virgin olive oil, and coffee provided at no cost to the participant (2) a healthy diet plus polyphenol supplementation (≈30g/day) from maqui , green tea, olive leaf, cranberry, and grape extracts, or (3) a control group receiving placebo and standard healthy diet recommendations. All groups will follow a caloric deficit. Dietary intake will be assessed using three 24-hour dietary recalls at baseline and 12 weeks, with polyphenol intake estimated via the Phenol-Explorer database. Data collection will include lifestyle questionnaires, anthropometric and bioimpedance measurements, blood pressure assessments, physical activity monitoring via accelerometers, and strength evaluations. Blood samples will be analyzed using a large-scale targeted metabolomics approach (UHPLC-MS/MS) to identify metabolic signatures, particularly those linked to gut microbiota. Faecal samples will be collected at baseline and visit 3. Findings will provide insights into how dietary polyphenols-either from whole foods or supplementation-affect obesity-related outcomes and cardiometabolic risk, potentially unveiling gut microbial biomarkers as future therapeutic targets. This study aims to contribute to strategies for obesity and cardiometabolic risk prevention and treatment.