Bioaccessibility via In Vitro Digestion and Colonic Fermentation, Intake, and per Serving Risk Assessment of Mn, Co, and Ni in Cooked Food

Manganese (Mn), cobalt (Co), and nickel (Ni) are trace elements whose nutritional and toxicological effects depend on their bioaccessibility (BA). This study evaluated the effects of food matrix, cooking, life stage, and childhood health status on Mn, Co, and Ni BA and estimated dietary exposure per serving. A total of 55 commonly consumed raw and cooked plant- and animal-based foods were analyzed. BA was assessed using a standardized in vitro oral–gastrointestinal digestion model followed by colonic fermentation with fecal inoculum from healthy adults and children. Metal concentrations were determined by ICP-MS/MS, and exposure was compared with nutritional and toxicological reference values. Plant-based foods showed significantly higher total MnBA and NiBA than animal-based foods (34.8 vs. 19.8% and 51.4 vs. 42.3%, respectively), whereas cooking generally increased MnBA, CoBA, and NiBA (expressed as the solubilized fraction available for absorption). Colonic fermentation substantially contributed to trace element BA, highlighting the role of gut microbiota. Healthy children exhibited higher colonic MnBA and CoBA than adults, while celiac and allergic children showed greater MnBA than healthy children. Mn and Co intakes remained below toxicological concern, whereas several foods provided relatively high Ni intakes, particularly for children. Overall, food composition, culinary processing, and gut microbiota influenced trace element BA and dietary risk assessment.