L-Phenylalanyl-L-leucine is primarily used in the field of biochemistry and medical research as a dipeptide with potential applications in studying peptide interactions and enzymatic processes. It serves as a substrate for investigating the activity of proteolytic enzymes, such as proteases, which play a critical role in breaking down proteins. This dipeptide is also utilized in the development of peptide-based drugs and therapeutic agents due to its structural properties. Additionally, it finds use in nutritional science as a component in specialized dietary supplements aimed at supporting muscle recovery and protein synthesis. Its role in research extends to exploring metabolic pathways and understanding the mechanisms of peptide absorption and utilization in biological systems.