Modelling the ageing gastrointestinal system in-vitro using whey protein isolate

The aims of this study were to adapt current <i>in-vitro</i> digestion protocols to replicate older adults suffering from gastrointestinal infections or those on polypharmacy. The whey protein breakdown was characterised within simulated gastric and intestinal phases, by measuring degree of hydrolysis, bio-accessible peptides, molecular weight distribution by Size Exclusion Chromatography, as well as peptide sequencing using High Resolution LC-MS. Differences due to older adult digestive conditions significantly affected the digestion of whey protein, seen by the presence of some aggregates and intact proteins, and less bio accessible peptides at the end of the gastric phase. These differences were also seen in the intestinal digesta, albeit to a lesser extent wheredistinct proteolytic profiles were seen. This study shows the importance of adapting the simulated gastrointestinal conditions to better represent the ageing gastrointestinal systems of our elderly population, and to better understand the poor protein assimilation by this ageing cohort.