Altered Digestive and Absorptive Characteristics of Food Proteins in Older Adults: Mechanisms, Model Applications, and Innovative Strategies

The global rise in the older adults highlights an urgent need for nutritional strategies capable of mitigating age-related declines in protein digestion and absorption. Simply increasing dietary protein intake is insufficient without improving protein bioavailability of protein in the elderly gastrointestinal tract is not addressed. This review critically evaluates the field and identifies several key findings to guide future studies and product development. First, protein sources and food matrices must be aligned with age-related physiological changes, including reduced digestive enzyme activity, diminished gastrointestinal motility, and alterations in gut microbiota composition. Liquid and semi-solid foods are more suitable for older adults with chewing or swallowing difficulties, and animal proteins generally exhibit higher digestibility than plant proteins in them. Second, emerging food-processing technologies, such as 3D printing, drying, extrusion, and homogenization, show substantial potential for improving protein bioavailability, particularly when combined with personalized formulation strategies. Third, elderly in vitro digestion models currently represent the practically valuable tools for evaluating protein bioaccessibility. Finally, successful translation into practice will require overcoming several key challenges, including the development of high-quality geriatric-specific datasets to support artificial intelligence (AI)-based predictive tools and the establishment of unified bioavailability assessment criteria and labeling frameworks. Collectively, these insights provide a conceptual roadmap to guide the development of scientifically grounded, personalized protein products for older adults.