Because your body doesn't make L-lysine on its own, you must get this amino acid from foods or supplements. You need about 1 gram of L-lysine per day, according to New York University Langone Medical Center, but people who eat protein-rich diets tend to get enough without supplementation. Foods such as cheese, nuts, eggs, meat and soybeans are good sources of L-lysine. Athletes, as well as vegetarians who don't consume legumes, may need more of the nutrient than their diet provides.
You need L-lysine for collagen production, which is vital for healthy skin and bones. Supplements of this nutrient may also help reduce flare-ups of oral or genital herpes, although studies show mixed results, according to the University of Maryland Medical Center. UMMC reports that the recommended daily supplement dosage is 12 milligrams per kilogram of body weight. One kilogram is 2.2 pounds, so a 150-pound person weighs about 68 kilograms and would take about 800 daily milligrams. To treat an active outbreak, doses may reach as high as 9,000 milligrams in a single day. See your doctor before taking L-lysine or any other supplements.