Intrinsic chicory root fibers modulate colonic microbial butyrate-producing pathways and improve insulin sensitivity in individuals with obesity

Type 2 diabetes and obesity have become major public health concerns. Growing evidence suggests that increased dietary fiber intake, through its interaction with the gut microbiota, may help prevent these diseases. Here, we demonstrate in a 12-week randomized, placebo-controlled trial in individuals at risk for type 2 diabetes that intake of an intrinsic fiber product, consisting of entire plant cells, tended to improve peripheral insulin sensitivity (p = 0.085), increased whole-body insulin sensitivity (p = 0.032), reduced circulating triglycerides (p = 0.049), and tended to reduce intrahepatic lipid content (p = 0.063), along with an increased proportion of small adipocytes (p = 0.008). Phylogenetic and metagenomic analysis revealed that these outcomes coincided with increased levels of fiber-degrading Bifidobacterium spp. and butyrate-producing Anaerostipes spp. and a functional shift toward a distal butyrogenic trophic chain while the best responding individuals had increased levels of pectin degraders that may produce propionate. Our findings demonstrate the pivotal role of slowly fermented, intrinsic plant cell fibers in improving cardiometabolic health. This study was registered at ClinicalTrials.gov (NCT04714944).