Lysine is an essential amino acid that must be obtained through diet or supplemental intake. Lysine is required for the production of all proteins in the body and is necessary for the maintenance of the structural proteins collagen and elastin, which make up all connective tissues, such as skin, tendons, and bones. property L-Lysine is also a precursor to L-carnitine, which is necessary for fat metabolism and energy production. Additionally, L-Lysine may help support a healthy immune system and good cardiovascular function. Studies have shown that lysine is one of the most effective methods for combating the herpes virus, which causes cold sores and genital herpes.