ʟ-Lysine SAP Lysine is classified as being an essential amino acid for human health. This means that lysine has to be consumed in adequate amount in the diet and cannot be synthesized from other amino acids in the body. Lysine is found in highest concentrations in animal protein sources such as meat and dairy. Lower amounts are found in proteins from grain products such as corn and wheat. Lysine is required by the body for many functions, including the synthesis of various connective tissues such as skin, collagen, elastin, and bone. Lysine is also required for the synthesis of carnitine, a nonessential amino acid that assists in the conversion of fatty acids to energy. This is an important function for the health of the immune system, and especially important for antiviral activity. This is one of the reasons that lysine has benefit in treating the herpes simplex virus (HSV) infections also known as cold sores. Lysine has also been shown to help absorb calcium and decreases the amount of calcium excreted in the urine.