Digestive fate of milk and egg-derived amyloids: Attenuated digestive proteolysis and impact on the trajectory of the gut microbiota

In an era in which protein consumption is enthusiastically advocated, this work explored the possible formation of proteinaceous amyloids in foods and their unchartered digestive fate. Evidence herein corroborates processing induces formation of amyloid-like architectures from β-lactoglobulin or ovalbumin. Such supramolecular assemblies exhibit attenuated susceptibility to gastric and intestinal proteolysis and may persist into the colon as confirmed by SDS-PAGE, LCMS, ThT analysis and TEM imaging. Human fecal fermentations of fibrils or their native protein counterparts establish that fibrilization helps maintain microbial diversity, low Firmicutes/Bacteroidetes ratio (Av. F/B ratio<3.00) and protect the butyrate producing genera Roseburia and Clostridium. In addition, fibrilization increased the minimal inhibitory concentration (MIC) of ovalbumin by at least two orders of magnitude without altering its negligible cytotoxicity. Further, In silico analyses support that both fibrils divert predicted microbiota metabolic trajectories towards those observed in fermentation of prebiotics. Thus, this work provides reassuring evidence against possible adverse effects of fibrilization of edible proteins. Yet, human trials with processed foods should be warranted to clinically affirm these findings.