The microbiome-mitochondria axis: the context-dependent role of urolithin A in aging and cancer via mitophagy.

Urolithin A (UA) is a gut microbiota-derived metabolite formed from dietary ellagitannins and ellagic acid. It has drawn sustained interest because it can influence mitochondrial quality control, but the evidence does not support a simple anti-aging or anticancer label. In this review, UA is examined across microbial metabolism, urolithin metabotypes, pharmacokinetic exposure, mitophagy biology, aging-related phenotypes, and cancer. The emphasis is placed on what has been shown, what remains model-dependent, and where translational claims are still premature. Preclinical work links UA to PINK1/Parkin-, TFEB-, AMPK-, sirtuin-, and Nrf2-associated pathways, with reported improvements in mitochondrial turnover and inflammatory signaling. Human data are narrower: most trials have been short and have focused on safety, muscle performance, mitochondrial signatures, and circulating biomarkers. Evidence for cancer prevention or cancer therapy still comes mainly from cell and animal studies. Because mitophagy can limit early mitochondrial damage but may also help established tumors survive hypoxia, nutrient restriction, dormancy, and therapy-induced stress, UA is better regarded as a microbiome-dependent mitochondrial modulator whose effects depend on biological setting. The next step is to define direct molecular targets, test native and conjugated UA at human-relevant exposure ranges, account for UM-A, UM-B, and UM-0 metabotypes, and evaluate cancer-specific endpoints before making therapeutic claims.