Lysine is an essential amino acid, one that you need to get from food. Some evidence suggests that supplemental lysine may be able to help prevent herpes infections (cold sores and genital herpes).

Most people need about 1 g of lysine per day. The requirement may be greater for athletes and people recovering from major injuries, especially burns. The richest sources of lysine are animal proteins such as meat and poultry, but it is also found in dairy products, eggs, and beans.