Lysine

What is lysine?

Lysine is an essential amino acid ^[1]. In foods, lysine is incorporated into proteins.

Lysine abbreviation (symbol): Lys

Functions of Lysine in the Human Body

Lysine is ^[1]:

• Important for the synthesis of carnitine (a substance that helps to convert fats into energy) and collagen (a protein which gives strength to the bones, cartilage and skin) and other proteins and for calcium absorption
• A ketogenic amino acid — it can be converted into ketones ^[16]
• Not a glucogenic amino acid — it cannot be converted into glucose ^[16]
• Basic (pH >7) amino acid; the other 2 basic amino acids are arginine and lysine ^[15]

Lysine Rich Foods

• ANIMAL FOODS: beef, pork, poultry, sardines, spirulina, soy products, brewer’s yeast, eggs
• PLANT FOODS: green beans, peas, lentils, spinach, amaranth, nuts, fenugreek seed
• Reference: ^[4]

Foods low in lysine: grains (wheat, millet, bulgur, kamut, corn, oats, barley, rice), potatoes, tapioca, seeds and nuts ^[2,4].

Hyperlysinemia

Hyperlysinemia is a rare genetic disorder with increased blood lysine levels due to a lack of the enzyme that breaks down lysine. The affected individuals usually have no symptoms but some may have intellectual disabilities or behavioral problems; a low-protein diet is sometimes prescribed ^[3].

Lysinuric Protein Intolerance (LPI)

Lysinuric protein intolerance (LPI) is a rare hereditary (autosomal recessive) disorder with a reduced absorption and increased excretion of amino acids lysine, ornithine and arginine due to a lack of related transport proteins in the intestinal and kidney tubules walls ^[5].

Symptoms develop in infants after weaning, when larger amounts of proteins are given to a child, and include vomiting, diarrhea, poor appetite, enlarged liver and spleen, muscle weakness and failure to thrive ^[5]. Coma may occasionally occur due increased blood ammonia levels after high-protein meals due to a reduced rate at which ammonia is converted to urea (which is excreted into urine).

Most patients can lead a normal life with a low-protein diet and oral lysine and citrulline supplements ^[5]. Complications include osteoporosis, and impaired function of lung, pancreas and kidneys due to protein deposits.

Lysine Deficiency

Lysine deficiency can occur in people on wheat-based diets low in legumes and animal protein. Symptoms include fatigue, nausea, agitation, impaired growth, anemia and reproductive disorders ^[1]. Lysine deficiency can result in vitamin B3 (niacin) deficiency and this can cause a disease called pellagra ^[7].

L-Lysine Supplements

Nonpresciption (over-the-counter) oral lysine supplements in the form of tablets, capsules and liquids include:

• Lysine dihydrochloride
• L-lysine monohydrochloride
• Calcium lysinate
• Lysortine (L-lysine monoorotate)
• L-lysine succinate
• Lysine clonixinate
• Lysine acetylsalicylate (the lysine salt of aspirin)

Creams containing lysine are also available.

L-Lysine Health Benefits

Lysine supplements are POSSIBLY EFFECTIVE in ^[6]:

• Treatment of lysine deficiency
• Replacement of lysine in individuals with lysinuric protein intolerance, but long term effects are questionable ^[11]
• Treatment of labial herpes — cold sores (using L-lysine monohydrochloride oral supplements or creams) ^[8,14,20,21]. 
• Relieving migraine headache (using lysine acetylsalicylate) ^[9]
• Increasing calcium absorption, but it is not clear if this can help in treatment of osteoporosis

Lysine supplements are PROBABLY INEFFECTIVE in the prevention or treatment of genital herpes ^[6,12,22] or increasing in growth hormone levels or muscle mass ^[17,18].

There is INSUFFICIENT EVIDENCE about the effectiveness of lysine supplements in the prevention or treatment of Alzheimer’s disease (dementia) ^[13], angina pectoris (heart-related chest pain), anxiety ^[8,10], canker sores ^[8], diabetes mellitus ^[8], osteoporosis ^[1], rheumatoid arthritis, increasing  improving exercise performance ^[8,18] or reducing glucose levels after carbohydrate meals ^[6].

Lysine and Growth Hormone

Oral lysine supplements can stimulate growth hormone release, but pre-workout lysine supplements in combination with resistance exercise can actually decrease the growth hormone release and does not likely have any anabolic effect on the muscles ^[19].

L-Lysine Safety: Side Effects, Toxicity

Lysine in oral doses up to 40 grams per day is POSSIBLY SAFE ^[6].

Side effects may include nausea, abdominal pain and diarrhea ^[6].

During Pregnancy

Not enough studies about the safety of lysine supplements during pregnancy and breastfeeding have been performed, so women should better avoid them during these periods ^[8].

L-Lysine-Drug Interactions

Lysine supplements may increase the absorption of supplemental calcium and enhance the toxicity of aminoglycoside antibiotics, such as gentamicin ^[1,6].

Who may need to avoid lysine?

Individuals with the following conditions may need to limit lysine intake from foods and supplements:

• Hyperlysinemia ^[3,6]
• Glutaric acidurua type 1 ^[11]
• Individuals with liver or kidney disease should avoid lysine supplements, except if prescribed by a doctor ^[6].