D-Phenylalanine is primarily used in the field of medicine and health supplements due to its potential therapeutic effects. It is often employed as a natural treatment for chronic pain conditions, such as arthritis and fibromyalgia, as it may help reduce discomfort by influencing the body's pain response mechanisms. Additionally, it is utilized in the management of depression and mood disorders, as it can enhance the production of neurotransmitters like dopamine and norepinephrine, which play a crucial role in regulating mood. Some studies suggest that D-Phenylalanine may also aid in improving focus and mental clarity, making it a component in nootropic formulations. Furthermore, it is explored for its potential benefits in managing symptoms of Parkinson's disease, though more research is needed in this area. In dietary supplements, it is often combined with other amino acids to support overall mental and physical well-being.