L-Lysine is an amino acid that has been proven necessary for human diets. It became popular when it was proven to reduce outbreaks of the herpes simplex virus. L-Lysine can be found naturally in wheat germ, fruits and vegetables, miso and yogurt. It is also known to promote bone health and energy.
L-lysine is protein amino acid. It is classified as an essential amino acid for humans and therefore must be supplied in the diet. Certain proteins, such as those found in meat, poultry and milk are rich in L-lysine. Proteins found in grains, cereals and their products are typically low in L-lysine. For example, wheat is low in L-lysine; wheat germ, however, is rich in L-lysine. Small amounts of free L-lysine are found in vegetables, vegetable juices and in such fermented foods as miso and yogurt.
L-lysine's popularity as a nutritional supplement arose as a result of some studies suggesting that the amino acid may decrease the recurrence rate of some infected with herpes simplex virus.
L-lysine is a basic amino acid and carries a positive charge at physiological pH. It is a solid substance that is very soluble in water. L-lysine has three pKa's: pKa1=2.20, pKa2=8.90 and pKa3=10.28. L-lysine is marketed as a nutritional substance, either as L-lysine monohydrochloride or as the free base, L-lysine. The molecular weight of L-lysine is 146.19 daltons, its molecular formula is C6H14N2O2, and its structural formula is:
L-lysine is also known as (S)- 2, 6, -diaminohexanoic acid and alpha, epsilon-diaminocaproic acid It is abbreviated as Lys or by its one letter abbreviation, K. L-lysine and lysine are frequently used interchangeably. The D-stereoisomer (D-lysine) is not biologically active.
Actions & Pharmacology
Supplemental L-lysine has putative anti-herpes simplex virus activity. There is preliminary research suggesting that it may have some anti-osteoporotic activity.
Mechanism of Action
Proteins of the herpes simplex virus are rich in L-arginine, and tissue culture studies indicate an enhancing effect on viral replication when the amino acid ratio of L-arginine to L-lysine is high in the tissue culture media. When the ratio of L-lysine to L-arginine is high, viral replication and the cytopathogenicity of herpes simplex virus have been found to be inhibited.
L-lysine may facilitate the absorption of calcium from the small intestine.
Following ingestion, L-lysine is absorbed from the lumen of the small intestine into the enterocytes by an active transport process. Some metabolism of L-lysine takes place within the enterocytes. That which is not metabolized is transported to the liver via the portal circulation. In the liver, L-lysine, along with other amino acids, participates in protein biosynthesis. Some is metabolized to L-alpha-aminoadipic acid semialdehyde, which is further metabolized to acetoacetyl-CoA. The intermediate in this pathway is saccharopine. L-lysine does not participate in transamination. It is the exception to the general rule that the first step in catabolism of an amino acid is the removal of its alpha-amino group by transamination to form the respective alpha-keto acid. L-lysine is both a glycogenic and a ketogenic amino acid. It can participate in the formation of D-glucose and glycogen, as well as lipids. It can also participate in the production of energy.
L-lysine that is not metabolized in the liver is transported to the various tissues of the body, where it is involved in reactions similar to those described above. L-hydroxylysine, found in collagen and elastin, is formed post-translationally.
Indications & Usage
Lysine may reduce the recurrence rate of herpes simplex virus (HSV) infections and/or reduce their severity in some, though research results have been mixed with respect to this putative benefit. Very preliminary research indicates a possible role for lysine in the prevention and treatment of osteoporosis.
There are no reports of overdosage with L-lysine.
Typical dosage used for possible prevention of herpes simplex virus recurrence is 500 mg to 3 grams daily. The average dose is 1 gram daily. Higher doses are split throughout the day.
LiteratureCivitelli R, Villareal DT, Agnusedei D, et al. Dietary L-lysine and calcium metabolism in humans. Nutrition. 1992; 8:400-405.Di Giovanna JJ, Blank H. Failure of lysine in frequently recurrent herpes simplex infection. Treatment and prophylaxis. Arch Dermatol. 1984; 120:48-51.Flondin NW. The metabolic roles, pharmacology, and toxicology of lysine. J Am Coll Nutr. 1997; 16:7-21.Griffith RS, De Long DC, Nelson JD. Relation of L-arginine—lysine antagonism to herpes simplex growth in tissue culture. Chemotherapy. 1981; 27:209-213.Griffith RS, Walsh DE, Myrmel KH, et al. Success of L-lysine therapy in frequently recurrent herpes simplex infection. Treatment and prophylaxis. Dermatologica. 1987; 175:183-190.Lo JC, Chertow GM, Rennke H, Seifter JL. Fanconi's syndrome and tubulointestinal nephritis in association with L-lysine ingestion. Am J Kidney Dis. 1996; 28:614-617.McCune MA, Perry HO, Muller SA, O'Fallon WM. Treatment of recurrent herpes simplex infections with L-lysine monohydrochloride. Cutis. 1984; 34:366-373.Rajamohan T, Kurup PA. Lysine: arginine ratio of a protein influences cholesterol metabolism: Part 1—studies on sesame protein having low lysine: arginine ratio. Indian J Exp Biol. 1997; 35:1218-1223.Thein DJ, Hurt WC. Lysine as a prophylactic agent in the treatment of recurrent herpes simplex labialis. Oral Surg Oral Med Oral Pathol. 1984; 58:659-666.
Research & Summary
A number of clinical studies have found that lysine is useful in preventing and sometimes shortening outbreaks of herpes simplex infections. A few studies have found no effect. In vitro and animal studies have also found evidence of lysine's anti-herpetic effects.
In a double-blind, placebo-controlled, multicenter trial of oral lysine, the treatment group received 1000 mg of lysine three times daily (3000 mg daily) for six months. During that period, the treated subjects had an average of 2.4 fewer HSV infections, and their symptoms were significantly less severe and healing times significantly reduced.
In another randomized, double-blind, cross-over study, a daily dose of 1248 mg (but not 624 mg) of lysine was found to decrease the recurrence rate of HSV in non-immunocompromised subjects. In this study, the 1248 mg dosage did not shorten healing time.
There is one study suggesting that supplemental lysine can both enhance intestinal absorption and improve renal conservation of absorbed calcium and that it might thus be helpful in osteoporosis. Further research is needed.
Contraindications, Precautions & Adverse Reactions
L-lysine supplementation is contraindicated in those with the rare genetic disorder hyperlysinemia/hyperlysinuria.
Pregnant women and nursing mothers should only consider using supplemental L-lysine if their diets are low in this amino acid. They should avoid supplemental L-lysine for other reasons.
Proteins such as casein, which are high in L-lysine relative to L-arginine, are associated with elevated cholesterol levels. Those with hypercholesterolemia who are interested in taking supplemental L-lysine should be aware of this.
Those with hepatic or renal failure should exercise caution in the use of supplemental L-lysine.
Doses up to 3 grams daily are generally well tolerated. Very high doses—greater than 10 to 15 grams daily—may cause gastrointestinal symptoms, such as nausea, abdominal cramps and diarrhea.
There is one report of Fanconi's syndrome and tubulointestinal nephritis in a 44-year old woman associated with the use of supplemental L-lysine.
Concomitant use of calcium supplements and L-lysine may increase calcium absorption. This is based on a very preliminary study that needs follow-up.