Microbial Metabolite, Macro Impact: Urolithin A in the Nexus of Insulin Resistance and Colorectal Tumorigenesis

Urolithin A (UA), a metabolite of dietary ellagitannins produced by the gut microbiome, is a potential dual-purpose bioactive compound that may interfere with the shared pathogenic pathways linking colorectal cancer (CRC) and type 2 diabetes mellitus (T2DM). This review summarizes recent preclinical and clinical data on UA's mechanisms, therapeutic potential, and translational challenges. In CRC models, UA promotes G2/M cell cycle arrest, triggers both intrinsic and extrinsic caspase-mediated apoptosis, enhances CD8+ T-cell mitophagy and memory functions, suppresses Wnt/β-catenin signaling, and reduces chemoresistance, especially to 5-FU. For T2DM, UA enhances autophagic flux, mitophagy, insulin signaling, and GLUT4-mediated glucose uptake through the AMPK and PI3K/AKT pathways, reduces fasting glucose and insulin resistance in animal studies, and promotes adipose tissue browning and mitochondrial beta-oxidation. Human biomarker research is limited but indicates positive changes following interventions that increase UA. Future priorities include biomarker-driven, dose-finding trials stratified by metabotype, developing colon-targeted vs. systemic formulations, and testing combinations with chemotherapy and immunotherapy to determine safety and effectiveness.