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

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.

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