Lysine is a building block for protein. It's an essential amino acid because your body cannot make it, so you need to obtain it from food. L-lysine is the form of lysine your body can utilize. It's naturally found in food and is the type used in supplements.  Lysine may also treat cold sores. Getting adequate amounts of amino acids, including lysine, along with other healthy nutrients may contribute to overall skin health. Lysine supplementation with its numerous health benefits may be useful in dealing with aging and slowing that process. This natural supplement may improve hair appearance, smooth the skin, reduce wrinkles. Lysine is an α-amino acid that is used in the biosynthesis of proteins.