Amyloids and Amyloid-like Protein Aggregates in Foods: Challenges and New Perspectives

Protein misfolding and amyloid formations are associated with many neurodegenerative and systemic diseases. The discovery of Alzheimer's disease and its association with the accumulation of Amyloid-& beta; (A & beta;) peptides in the plaques uncovered the pleiotropic nature of peptides/ proteins. As of today, more than 50 proteins/ peptides are reported to form amyloids or amyloid-like protein aggregates under different conditions, establishing that amyloid formation could be a generic property of many proteins. In principle, under certain conditions, all the proteins have this property to form amyloid-like aggregates, which can be toxic or non-toxic. The extensive research in this direction led to an understanding of the ubiquitous nature of amyloids. Mounting evidences suggest that processed foods, particularly protein-rich foods, could be a plethora of amyloids or amyloid-like protein aggregates. Many are reported to be toxic, and their consumption raises health concerns. The assimilation of dietary proteins in the human body largely depends upon their conformational states and the digestive integrity of the gastrointestinal system. Amyloids or amyloid-like protein aggregates are usually protease resistant, and their presence in foods is likely to reduce nutritional value. Several biochemical and biophysical factors, commonly evident in various food processing industries, such as high temperature, the addition of acid, etc., are likely to induce the formation of protease-resistant protein aggregates. Aging significantly alters gastrointestinal health, predisposing aged individuals to be more susceptible to protein aggregation-related diseases. Consumption of foods containing such protein aggregates will lead to a poor supply of essential amino acids and might exaggerate the amyloid-related disease etiology. On the other hand, the gut microbiome plays a crucial role during pathological events leading to the development of Alzheimer's and Parkinson's diseases. The activity of gastrointestinal proteases, pH change, gut microbiome, and intestinal epithelium integrity would largely determine the outcome of consuming foods loaded with such protein aggregates. The current review outlines the recent development in this area and a new perspective for designing safe protein-rich diets for healthy nutrition.