L-Lysine hydrochloride (HCl) is a crystalline form of the essential amino acid L-lysine, commonly used in dietary supplements and food fortification. As a crucial building block of protein, L-lysine is integral to numerous physiological processes in the body, including tissue repair, collagen synthesis, and immune function. The addition of hydrochloride to L-lysine enhances its stability and solubility, making it more suitable for various applications in the food and pharmaceutical industries. L-Lysine HCl supplementation has been studied for its potential benefits in supporting immune health, promoting tissue healing, and managing conditions such as herpes simplex virus infections. Additionally, L-Lysine HCl may play a role in enhancing calcium absorption and utilization, thereby contributing to bone health and the maintenance of proper nitrogen balance. With its versatile properties and essential role in human nutrition, L-Lysine HCl remains a valuable ingredient in dietary supplements and fortified foods, supporting overall health and well-being.