Toxic Metals and Metalloids Exposure and the Gut-Cardiometabolic Axis: A Narrative Review of Microbiome Dysbiosis, Gut Barrier Dysfunction, and Metabolic Inflammation.

Toxic elements and metalloids exposure is an important environmental contributor to cardiometabolic disease, yet the gut-mediated mechanisms linking toxic elements to systemic metabolic and vascular injury remain incompletely understood. Lead, cadmium, arsenic, and mercury can enter the gastrointestinal tract through contaminated food, water, dust, smoking, seafood, and occupational sources, allowing direct interaction with the intestinal lumen, epithelial barrier, immune system, and gut microbiome. This narrative review examines the gut-cardiometabolic axis as a mechanistic framework connecting toxic metal exposure to microbiome dysbiosis, barrier dysfunction, endotoxemia, microbial metabolite imbalance, and chronic metabolic inflammation. Available evidence, derived from human, animal, and in-vitro studies of varying quality, suggests that toxic elements may alter microbial diversity and function, affect tight-junction integrity, and increase intestinal permeability; however, a consistent metal-specific signature and a complete causal chain have not been established. These changes may promote lipopolysaccharide passage through the intestinal barrier, activate innate immune pathways, and maintain systemic inflammatory signaling. At the same time, disruption of microbial metabolite profiles, including lower short-chain fatty acid production and altered trimethylamine N-oxide, bile acid and uremic toxin pathways, may promote insulin resistance, dyslipidemia, endothelial dysfunction, hypertension, atherosclerosis and overall cardiometabolic vulnerability. Viewing toxic-metal exposure through the gut-cardiometabolic axis provides a hypothesis-generating framework for integrating exposure reduction with conventional cardiometabolic risk management; the clinical value of microbiome-targeted strategies remains to be established. Longitudinal and multi-omics studies are still needed to define causal relationships and identify populations at greatest susceptibility.