Dietary Aluminium Exposure and Human Health: Sources, Bioavailability, Toxicokinetics, and Health Risk Assessment

Background/Objectives: Aluminium is a widespread environmental element and food contaminant to which the general population is continuously exposed, primarily through diet and drinking water. Although gastrointestinal absorption is generally low, bioavailability varies according to chemical form, food matrix, and interactions with dietary components. Prolonged exposure can nevertheless result in gradual tissue accumulation. This review summarises current evidence on dietary aluminium exposure, factors influencing its bioavailability, toxicokinetics, biological effects, gut microbiota interactions, and population-level health risk. Methods: A comprehensive narrative literature review was conducted using publications retrieved from PubMed/MEDLINE, Scopus, Web of Science, and Google Scholar. Original research articles, review papers, and reports issued by international organisations were critically evaluated with particular emphasis on dietary sources, drinking water, food additives, food contact materials, gastrointestinal absorption, toxicokinetics, biological mechanisms, gut microbiota, and health risk assessment. Results: Food represents the principal source of aluminium exposure in the general population, while drinking water usually contributes a smaller but continuous fraction of total oral intake. Dietary exposure varies substantially between populations and is influenced by food composition, processing practices, the use of aluminium-containing additives, and migration from food contact materials. Aluminium bioavailability is modified by chemical speciation and dietary constituents, including citrate, phosphates, silicates, phytates, polyphenols, and essential minerals. Despite limited absorption, prolonged exposure can lead to gradual aluminium accumulation, particularly in bone tissue and the central nervous system. Proposed biological mechanisms include oxidative stress, mitochondrial dysfunction, disruption of mineral homeostasis, and inflammatory signalling. Emerging evidence also indicates that aluminium may alter the gut microbiota, impair intestinal barrier integrity, and influence the gut-brain axis. Population exposure assessments show considerable regional variation, with some groups approaching or exceeding established tolerable weekly intake values. Conclusions: Dietary aluminium exposure represents a relevant issue in nutritional toxicology and food safety. Although current evidence does not establish that typical dietary exposure directly causes chronic disease, long-term exposure, differences in bioavailability, and the possibility of elevated intake in selected population groups justify continued monitoring and further prospective human studies. Future research should integrate dietary intake, aluminium speciation, nutritional status, biomarkers of internal exposure, and long-term health outcomes to improve risk assessment and support effective exposure-reduction strategies.