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 required for the synthesis of carnitine, a non-essential amino acid that helps convert fatty acids into energy. This is an important function for immune system health and is particularly important for antiviral activity. This is one reason why lysine is beneficial in treating herpes simplex virus (HSV) infections, also known as cold sores.
Lysine has also been shown to help absorb calcium and decrease the amount of calcium excreted in the urine.