Lysine is among the most common of all amino acids. From a nutritional standpoint, it is classified as essential; meaning that it cannot be metabolized within the human body and must be obtained from external dietary sources or supplements. Lysine is most concentrated in muscle tissue. It remains a central component in processes relating to energy production, growth and development, and maintenance of lean body mass.
Lysine provides for other fundamental processes within the human body as well. It is principal in the production of carnitine, an amino acid which has been shown to lower cholesterol by assisting the body in the conversion of fatty acids. Lysine is also a key ingredient in collagen formation. Collagen is important for the integrity of bone and connective tissues; including tendon, cartilage, and skin. The absorption and conservation of calcium is equally dependant upon adequate lysine levels. 
The importance of lysine in roles of growth and development may be among its most significant responsibilities. Infants and children often require a substantially greater amount than adults. Sufficient amounts of lysine must be achieved because of its incorporation into certain bodily proteins. These specific proteins allow for vital physiological tasks to be accomplished, including the production of specialized hormones, enzymes, and disease-fighting antibodies.
Of special interest, lysine is widely employed in the cooking process. It is often used in the browning reaction (carmelization) of pastries, cookies, cereals, and doughnuts. As lysine and sugar become connected in this process, the absorption of lysine is severely inhibited.
Significant amounts of lysine are found protein-rich foods. Meats (red meat, poultry, pork), cheeses (parmesan), fish (cod, sardines), nuts, eggs, soy products (tofu, soy protein, flour), spirulina, and legumes contain the highest concentrations of lysine. Lysine is the most sensitive amino acid in regards to food preparation and processing. Serving sizes below are based upon 100 grams of a given food source and are expressed in milligrams, representing the amount of lysine contained.
|3158||Leavening agents, yeast, baker’s, active dry|
|Vegetables and Vegetable Products|
|3025||Seaweed, spirulina, dried|
|Legumes and Legume Products|
|5327||Soy protein isolate|
|3928||Soy protein concentrate|
|3157||Tofu, dried-frozen (koyadofu)|
|3157||Tofu, dried-frozen (koyadofu), prepared with calcium sulfate|
|3097||Soy flour, low-fat|
|2991||Soy meal, defatted, raw|
|Finfish and Shellfish Products|
|5769||Fish, cod, Atlantic, dried and salted|
|3053||Beef, round, top round, separable lean only, trimmed to 1/4” fat, all grades, cooked, braised [London Broil, Minute Steak, Round Steak]|
|3010||Beef, round, top round, separable lean only, trimmed to 0” fat, all grades, cooked, braised [London Broil, Minute Steak, Round Steak, Cube steak]|
|3180||Pork, cured, bacon, cooked, pan-fried|
|3072||Pork, cured, bacon, cooked, broiled, pan-fried or roasted, reduced sodium|
|Lamb, Veal, and Game Products|
|3138||Lamb, domestic, shoulder, arm, separable lean only, trimmed to 1/4” fat, choice, cooked, braised|
|3134||Game meat, bison, chuck, shoulder clod, separable lean only, 3-5 lb roast, cooked, braised [buffalo]|
|2980||Veal, leg (top round), separable lean and fat, cooked, braised|
|Dairy and Egg Products|
|5515||Egg, white, dried|
|3844||Cheese, parmesan, shredded|
|3402||Egg, whole, dried|
|2980||Cheese, parmesan, grated|
|3460||Gelatins, dry powder, unsweetened|
Clinical research highlighting the value of lysine supplementation in human physiology has been promising. Cholesterol, athletic performance, tissue recovery, osteoporosis, and herpes simplex-related infections, are all topics of ongoing research into the benefits of lysine supplementation.
Older adults suffering from osteoporosis may directly benefit from additional supplementation of L-Lysine. Lysine improves the absorption of calcium from the digestive tract, and prevents the loss of calcium in the urea cycle. Supplemental dosages of L-Lysine may help to maintain bone mineral density, while preventing further bone loss in persons suffering from arthritic conditions.  Research suggests that L-Lysine, combined with L-arginine, assists in the formation of protein rich collagen and increases the action of bone-building cells.
The most promising application of supplemental lysine may be its ability to prevent and manage herpes-simplex related infections. These conditions arise as the result of the herpes simplex virus (HSV). Two types of viruses exist and influence the severity of infection:
- Type I - characterized by cold sores/fever blisters around the oral region
- Type II - manifests in the genital region, causing painful and unsightly sores
Supplemental L-Lysine may be used to treat both the herpes simplex virus and herpes varicella-zoster viruses.  The latter (herpes zoster virus) is responsible for the activation and reactivation of painful shingles blisters.
Lysine inhibits the growth of the herpes simplex virus by competing with (and ultimately taking the place of) arginine for absorption into tissue cells. Studies recommend a diet with a balanced amount of both arginine and lysine for preventative measures against these viruses; though excessive amounts of arginine may aggravate herpes, further influencing the likelihood of outbreak.
Lysine may also be effective when used in combination with ascorbic acid (Vitamin C) for the prevention and treatment of symptoms associated with migraine headaches and angina (chest pain or discomfort due to coronary heart disease). [5, 6]
The median range for lysine dosage is 12 milligrams per kilogram of bodyweight daily. The Recommended Dietary Allowance (RDA) for lysine is expressed in milligrams below:
|Requirement - mg. per kg. of body weight|
|Amino acid||Infant 3-6 mo.||Child 10-12 yr.||Adults|
|Histidine||33||not known||not known|
|S-containing amino acids||45||22||10|
|Aromatic amino acids||132||22||16|
Adults with herpes simplex should also be aware of these additional dosage guidelines:
|Canker Sores||500 mg L-lysine 3 times a day|
|Cold Sores||1,000 mg L-lysine 3 times a day for flare-ups, then 500 mg a day|
|Shingles||1,000 mg L-lysine 3 times a day during acute stage; to help prevent recurrences, 1,000 mg a day|
In addition, the U.S. National Academy of Sciences recommends that healthy people achieve .36 grams of highly bioavailable protein for each pound of bodyweight - equaling 0.8 grams of protein, per kilogram of bodyweight.
Deficiencies of lysine are characterized by “anemia, bloodshot eyes, enzyme disorders, hair loss, an inability to concentrate, irritability, lack of energy, poor appetite, reproductive disorders, retarded growth, and weight loss.” 
Individuals at greatest risk include; vegetarians (primarily vegans), persons involved in frequent vigorous activities (athletes), burn patients, alcoholics/drug addicts, and persons consuming excessive amounts of cereals and baked goods that contain high amounts of simple sugars.
Exceptionally high intakes of lysine (15 - 40 grams per day), may result in transient diarrhea and abdominal cramping.  Although not observed in humans, animals have exhibited increased risks for the development of gallstones and an elevation in cholesterol, as a direct consequence of excessive intakes of lysine. 
1. Citivelli R, Villareal DT, Agneusdei D, et al. Dietary L-Lysine and calcium metabolism in humans. Nutrition 1992;8: 400-4.
2. Nutrition Data. “999 Foods; Highest in Lysine.” (2004) http://www.pdrhealth.com/drug_info/nmdrugprofiles/herbaldrugs/101840.shtml
3. Furst P. Dietary L-Lysine supplementation; a promising nutritional tool in the prophylaxis and treatment of osteoporosis. Nutrition. 1993;9(1): 71-72.
4. Griffith RS, Walsh DE, Myrmel KH, Thompson RW, Behforooz A. Success of L-Lysine therapy in frequently recurrent herpes simplex infection. Treatment and prophylaxis. Dermatologica. 1987;175(4): 183-190.
5. Krymchantowski AV, Barbosa JS, Cheim C, Alves LA. Oral lysine clonixinate in the acute treatment of migraine: a double blind placebo-controlled study. Arq Neuropsiquiatr. 2001;59(1):46-49.
6. Pauling L. Case Report: Lysine/Ascorbate-related Amelioration of Angina Pectoris. J Orthomolecular Med. 1991;6:144-46.
7. Zest for life information page. “RDA of amino acids.” (1999-2003) http://www.pdrhealth.com/drug_info/nmdrugprofiles/herbaldrugs/101840.shtml (14 Sept. 2004).
8. WholeHealthMD.com supplements page. “Lysine.” (2000) http://www.wholehealthmd.com/refshelf/substances_view/1,1525,862,00.html
9. Balch, Phyllis A., James F. “Amino Acids.” Prescription for Nutritional Healing. Ed. Amy C. Tecklenberg. New York, NY: Penguin Putnam Inc., 3rd Ed. 2000. 42-53.
10. Flodin NW. The metabolic roles, pharmacology, and toxicology of lysine. J Am Coll Nutr 1997;16:7-21 [review].
11. Leszczynski DE, Kummerow FA. Excess dietary lysine induces hypercholesterolemia in chickens. Experientia 1982;38:266-7.