Impact of the physiological stage on the bioaccessibility of α-tocopherol from fortified yogurts using dynamic in vitro digestion simulating young and old adults' gastrointestinal conditions

Age-related physiological decline negatively impacts nutrient digestion and absorption, making older adults more susceptible to diet-related diseases. Fortified and functional foods are promising strategies to enhance the delivery of nutraceuticals and bioactive compounds. However, understanding how these foods behave under age-specific gastrointestinal conditions is essential. Despite the relevance of in vitro gastrointestinal models, there is a lack of dynamic systems that accurately replicate the digestive physiology of older adults. This study employed the DIDGI® dynamic in vitro gastrointestinal model, following the INFOGEST guidelines, to simulate the digestive processes of both young and old adults. Fortified yogurts containing α-tocopherol encapsulated in oil-in-water nanoemulsions were tested to assess the impact of age-related digestive conditions on digestibility and release kinetics of α-tocopherol. The intestinal recovery of α-tocopherol was significantly higher in the young adult model (97.3 ± 5.9 %) compared to the older adult model (79.8 ± 5.2 %). Although bioaccessibility during the intestinal phase was comparable in both models (ranging from 60.54 ± 7.38 % to 78.90 ± 8.88 %), the overall estimated bioavailability was significantly greater in the young adult model (67.76 ± 7.15 %) than in the older adult model (57.59 ± 4.50 %). Distinct release kinetics were also observed between models, indicating that physiological stage significantly affects nutrient release and absorption. This study demonstrates that aging alters digestive function, impacting the bioavailability of encapsulated bioactives. These findings underscore the importance of developing age-specific fortified foods and digestion models to optimize nutritional support for older adults.