Foods for Aromatic Amino Acid Metabolism Disorder: A Review of Current Status, Challenges and Opportunities

Aromatic amino acids (AAA), including phenylalanine (Phe), tyrosine (Tyr), and tryptophan (Trp), are essential building blocks of proteins, however, they have been implicated in multiple amino acid metabolism diseases, such as phenylketonuria, tyrosinemia, and glutaric acidemia type I. Dietary therapy is indispensable for patients with AAA metabolism disorder. This review briefly describes the pathogenesis and nutritional treatment guidelines of several AAA metabolic diseases. The techniques of protein hydrolysis and AAA removal from raw protein materials are very important in the development of special medical foods (SMFs) for above diseases. Therefore, existing protein hydrolysis techniques including enzymatic and microbial hydrolysis are reviewed, and the widely applied AAA removing methods including ultrafiltration and adsorption by active carbon and resin are also discussed. In addition, the application of several promising materials to remove AAA with better selectivity, such as molecular imprinting polymer, cyclodextrin, TiO2 and carbohydrate-based reverse micelle are prospected. This review may promote the development of SMFs for AAA metabolic diseases, and provide potential directions for processing technology improvement.