Lysine is one of the essential amino acids that your body needs to build proteins. Since our bodies can’t produce essential amino acids, including lysine, diet is the only way to make sure you’re getting it.

Lysine plays an important role in supporting the immune system. It may also improve athletic performance.

Protein hormones stabilize the basic functions of the body, like sleep and metabolism. These protein hormones, like insulin, melatonin, and growth hormones, are composed of hundreds of thousands of amino acid chains. Cells in the body are constantly being broken down and restored, so your body needs amino acids like lysine to produce new hormones. Antibodies, which help the body fight viruses and infection, are made of proteins. And enzymes, which aid in all your body’s processes including digestion, are also made of these proteins.

Lysine is even used by your body to create collagen, the primary structural protein in the skin.