L-Lysine SAPAmino acid for antiviral activity (based on science) Lysine is classified as an essential amino acid for human health. This means that lysine must be consumed in adequate amounts in the diet and cannot be synthesized from other amino acids in the body. Lysine is required by the body for many functions, including the synthesis of various connective tissues such as skin, collagen, elastin and bones. Lysine is also necessary for the synthesis of