Lysine (abbreviated as Lys or K) is an a-amino acid. This amino acid is an essential amino acid, which means that humans cannot synthesize it. Lysine is a base, as are arginine and histidine.

L-Lysine is a necessary building block for all protein in the body. L-Lysine plays a major role in calcium absorption; building muscle protein; recovering from surgery or sports injuries; and the body's production of hormones, enzymes, and antibodies.

It has been suggested that lysine may be beneficial for those with herpes simplex infections.

References

Griffith RS, Norins AL, Kagan C. (1978). "A multicentered study of lysine therapy in Herpes simplex infection". Dermatologica. 156 (5): 257–267. PMID 640102.