Link between gut microbiota and health outcomes in inulin -treated obese patients: Lessons from the Food4Gut multicenter randomized placebo-controlled trial

Background: The gut microbiota is altered in obesity and is strongly influenced by nutrients and xeno-biotics. We have tested the impact of native inulin as prebiotic present in vegetables and added as asupplement on gut microbiota-related outcomes in obese patients. Metformin treatment was analyzed asa potential modulator of the response. Methods: A randomized, single-blinded, multicentric, placebo-controlled trial was conducted in 150obese patients who received 16 g/d native inulin versus maltodextrin, coupled to dietary advice toconsume inulin-rich versus -poor vegetables for 3 months, respectively, in addition to dietary caloricrestriction. Anthropometry, diagnostic imaging (abdominal CT-scan,fibroscan), food-behavior ques-tionnaires, serum biology and fecal microbiome (primary outcome; 16S rDNA sequencing) were analyzedbefore and after the intervention. Results: Both placebo and prebiotic interventions lowered energy intake, BMI, systolic blood pressure,and serumg-GT. The prebiotic induced greater weight loss and additionally decreased diastolic bloodpressure, AST and insulinemia. Metformin treatment compromised most of the gut microbiota changesand metabolic improvements linked to prebiotic intervention. The prebiotic modulated specific bacteria,associated with the improvement of anthropometry (i.e. a decrease inDesulfovibrioandClostridium sensustricto). A large increase inBifidobacteriumappears as a signature of inulin intake rather than a driver ofprebiotic-linked biological outcomes