Lysine is an essential amino acid, which means that it is essential to human health but cannot be manufactured by the body. For this reason, lysine must be obtained from food. Amino acids are the building blocks of protein. Lysine is important for proper growth and it plays an essential role in the production of carnitine, a nutrient responsible for converting fatty acids into energy and helping to lower cholesterol. Lysine appears to help the body absorb and conserve calcium and it plays an important role in the formation of collagen, a substance important for bones and connective tissues including skin, tendon, and cartilage.

If there is too little lysine in the diet, kidney stones and other health related problems may develop including fatigue, nausea, dizziness, loss of appetite, agitation, bloodshot eyes, slow growth, anemia, and reproductive disorders. It is extremely rare, however, to obtain insufficient amounts of lysine through the diet. Generally, only vegetarians who follow a macrobiotic diet and certain athletes involved in frequent vigorous exercise are at risk for lysine deficiency. For vegetarians, legumes (beans, peas and lentils) are the best sources of lysine.

Lysine is involved in the browning reaction, or carmelization, in foods such as pastries, doughnuts, cookies and cereals. In this process, lysine and sugar become linked together in a way that makes lysine difficult for the body to absorb. As a result, a diet high in cereals and baked goods, especially those that contain a lot of simple sugars, can result in low lysine intake.

Herpes and Shingles
L-lysine can be used to treat mouth and genital lesions caused by herpes simplex virus as well as shingles caused by herpes zoster viruses. Taking lysine supplements can speed recovery time and reduce the chance of recurrent breakouts of the herpes infection.

Osteoporosis
L-lysine helps improve the absorption of calcium from the digestive tract and prevent loss of calcium in the urine. In so doing, some researchers speculate that L-lysine may help prevent bone loss associated with osteoporosis. In addition, test tube studies suggest that L-lysine in combination with L-arginine (another amino acid) increases the activity of bone-building cells and enhances production of collagen.

Other
Certain forms of lysine and/or lysine bound to anti-inflammatory medications may help alleviate pain following an episiotomy (a procedure performed during labor that involves cutting the vaginal area to enlarge the vaginal opening and facilitate delivery). These forms of lysine may also relieve migraine headaches and painful periods. Whether L-lysine and other readily available lysine supplements also offer these benefits is not known.

Good sources of lysine are foods rich in protein including meat (specifically red meat, pork, and poultry), cheese (particularly parmesan), certain fish (such as cod and sardines), nuts, eggs, soybeans (particularly tofu, isolated soy protein, and defatted soybean flour), spirulina, and fenugreek seed.

Lysine is available in tablets, capsules, creams, and liquids, and is usually sold in the L-lysine form.

A healthcare provider can help determine whether your diet provides enough lysine. If your diet does not contain sufficient lysine, a healthcare practitioner may recommend lysine supplements as part of a complete amino acid replacement.

The daily recommended dietary allowances (RDA) of lysine are listed below:

Pediatric

• Birth to 4 months: 103 mg per kilogram of body weight per day
• Children 5 months to 2 years: 69 mg per kilogram of body weight per day
• Children 3 to 12 years: 44 mg per kilogram of body weight per day

Adult

• 13 and older: 12 mg per kilogram of body weight per day

Some experts suggest that adults may need up to 30 mg per kilogram of body weight per day.

Adults with herpes simplex should follow these guidelines:

• To treat symptoms: 3,000 – 9,000 mg per day in divided doses
• To prevent recurrences: 500 – 1,500 mg per day

Because of the potential for side effects and interactions with medications, dietary supplements should be taken only under the supervision of a knowledgeable healthcare provider.

Lysine supplements are considered safe and nontoxic. However, one animal study found that chicks fed with L-lysine developed elevated cholesterol and triglyceride levels. For this reason, individuals with cardiovascular disease and those with elevated cholesterol and/or triglyceride levels should consult a healthcare practitioner before taking lysine supplements.

There are no reports in the scientific literature to suggest that lysine interacts with any conventional medications.

Bruzzese N, Sica G, Iacopino F, et al. Growth inhibition of fibroblasts from nasal polyps and normal skin by lysine acetylsalicylate. Allergy. 1998;53:431–434.

Civitelli R, Villareal DT, Agnusdei D, Nardi P, Avioli LV, Gennari C. Dietary L-lysine and calcium metabolism in humans. Nutrition. 1992;8(6):400-405.

De los Santos AR, Marti MI, Espinosa D, Di Girolamo G, Vinacur JC, Casadei A. Lysine clonixinate vs. paracetamol/codeine in postepisiotomy pain. Acta Physiol Pharmacol Ther Latinoam. 1998;48(1):52–58.

Di Girolamo G, Zmijanovich R, de los Santos AR, Marti ML, Terragno A. Lysine clonixinate in the treatment of primary dysmenorrhea. Acta Physiol Pharmacol Ther Latinoam. 1996;46(4):223-232.

Fini M, Torricelli P, Giavaresi G, Carpi A, Nicolini A, Giardino R. Effect of L-lysine and L-arginine osteoblast cultures from normal and osteopenic rats. Biomed Pharmacother. 2001;55(4):213-220.

Flodin NW. The metabolic roles, pharmacology, and toxicology of lysine. J Am Coll Nutr. 1997;16:7–21.

Furst P. Dietary L-lysine supplementation: a promising nutritional tool in the prophylaxis and treatment of osteoporosis. Nutrition. 1993;9(1):71-72.

Griffith RS, Walsh DE, Myrmel KH, Thmpson RW, Behforooz A. Success of L-lysine therapy in frequently recurrent herpes simplex infection. Treatment and prophylaxis. Dermatologica. 1987;175(4):183-190.

Hugues FC, Lacoste JP, Danchot J, Joire JE. Repeated doses of combined oral lysine acetylsalicylate and metoclopramide in the acute treatment of migraine. Headache. 1997;37:452–454.

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.

Pizzorno JE, Murray MT. Textbook of Natural Medicine. Vol 1. 2nd ed. Edinburgh: Churchill Livingstone; 1999.

Schmeisser DD, Kummerow FA, Baker DH. Effect of excess dietary lysine on plasma lipids of the chick. J Nutr. 1983;113(9):1777-1783.

Shils ME, Olson JA, Shike M, Ross AC. Modern Nutrition in Health and Disease. 9th ed. Baltimore, Md: Williams & Wilkins; 1999:41;1,010.

Tfelf-Hansen P. The effectiveness of combined oral lysine acetylsalicylate and metoclopramide in the treatment of migraine attacks. Comparison with placebo and oral sumatriptan. Funct Neurol. 2000;15(Suppl 3):196-201.

Werbach MR. Nutritional Influences on Illness. 2nd ed. Tarzana, Calif: Third Line Press; 1993:159–160, 384, 434, 494–495, 506, 580, 613–614, 636.