Lysine or L-lysine is an essential amino acid, meaning that it is not made in the body and must be supplied by dietary intake from food or supplements.
L-lysine is like a building block for body proteins like collagen and is required in the manufacture of hormones, antibodies, and enzymes. It also plays a role in growth and development, calcium absorption, proper brain function, recovery from injury, and many other body processes. L-lysine is also converted in the body to carnitine, which is required for the transport of fatty acids into the mitochondria for energy production.
L-lysine is found in the highest concentrations in high-protein foods such as meat, fish and other seafood, dairy products, soy, and nuts and seeds.
Generally, a diet that provides sufficient protein levels will meet the body’s requirement of L-lysine (approximately 2.5 grams per day).
In diets that are insufficient in L-lysine, it is not enough to supplement only L-lysine. In fact, in low-protein diets, supplementing with L-lysine alone further lowers the protein quality of the diet.1 Hence, L-lysine supplementation is not recommended for people consuming a low-protein diet.
Instead, supplements providing all essential amino acids or high-quality protein sources like whey or egg white are recommended for these individuals.
L-lysine supplementation may offer benefits in five applications.
There are two types of Herpes simplex virus (HSV): type 1 (HSV-1) is most often responsible for cold sores (also referred to as fever blisters), while type 2 (HSV-2) is responsible for nearly 90% of cases of genital herpes (the remaining 10% are caused by HSV-1).
An initial HSV-1 infection may cause fever, painful swelling, and open sores on the gums and inside the cheeks, or a painful, sore throat that usually develops 2 to 12 days after exposure to someone with HSV-1. Recurrences are mostly limited to the presence of cold sores/fever blisters.
Symptoms of a first episode of genital herpes can include an itching or burning sensation; pain in the legs, buttocks, or genital area; vaginal discharge; or a feeling of pressure in the abdominal region. Within a few days, sores (lesions) appear at the site of infection. Lesions also can occur on the cervix in women or in the urinary passage in men. These small red bumps may develop into blisters or painful open sores. Over a period of days, the sores become crusted and then heal without scarring. Other symptoms that may accompany a primary episode of genital herpes can include fever, headache, muscle aches, painful or difficult urination, vaginal discharge, and swollen glands in the groin area.
After the initial infection of either HSV-1 or HSV-2, the virus travels to the sensory nerves at the end of the spinal cord and makes a home. In most people, the virus becomes dormant (inactive). In others, however, it can be reactivated. When the virus becomes reactivated, it travels along the nerves to the skin, where it multiplies on the surface at or near the site of the original herpes sores, causing new sores to erupt. It can also reactivate without causing any visible sores.
The popularity of L-lysine arose from research showing that lysine has antiviral activity in test tube studies conducted in the 1960s.2 This action of L-lysine was found to be due to the blocking of L-arginine, another amino acid. Since much of the inhibitory effect of L-lysine is due to this inhibition of L-arginine, in order for L-lysine supplementation to be effective in reducing herpes virus reactivation, the dietary intake of foods high in L-arginine and low in L-lysine must be restricted.
In addition to the test tube studies indicating the need for this dual approach, results from double-blind studies on the effectiveness of L-lysine supplementation have shown that avoiding L-arginine-rich foods produces inconsistent results.3
When L-lysine was given at a dosage of 1 gram three times daily along with dietary restriction of foods high in L-arginine and low in L-lysine, such as nuts and seeds, chocolate, peanuts, and gelatin/collagen, studies have shown very good results.3-6 For example, in one double-blind study of subjects with recurrent cold sores, at six months of use, L-lysine was rated as effective or very effective in 74% compared to only 28% for those who received the placebo.4 There were fewer recurrences, milder symptoms, and lesions healed quicker in the L-lysine group.
Positive results were also seen in a long-term clinical study with subjects with recurrent HSV-2 who experienced at least four or more episodes per year.6 After the first year, L-lysine supplementation (500 mg per day) along with a diet that restricted foods high in L-arginine and low in L-lysine suppression produced a 63% reduction in the number of annual recurrences and a 49% reduction in lesion repair time. These same patients were followed for 8 years, with the protocol of 500 mg per day of L-lysine for 30 days every 12 months while maintaining a diet that restricted foods high in L-arginine and low in L-lysine. If the subjects felt a recurrence was starting, they immediately increased the L-lysine dosage to a single dosage of 3 g per day until symptoms subsided. This protocol significantly reduced recurrences and healing time if a recurrence occurred.
The bottom line from all the clinical evidence is that for best results, L-lysine must be used preventatively or started immediately as soon as symptoms begin to appear (prodromal phase) and must be combined with a restriction in foods that are high in L-arginine and low in L-lysine.3
L-lysine may play a role in reducing feelings of anxiety or stress based on preliminary scientific evidence in both animal and human studies. For example, one study found that adding lysine to wheat flour in villages in Syria helped reduce anxiety scores and the stress hormone cortisol.7
In another double-blind clinical study in Japan, the week-long oral supplementation with L-lysine (2.64 g per day) and L-arginine (2.64 g per day) reduced feelings of stress and anxiety as well as decreased levels of salivary cortisol and chromogranin-A (a marker of the stress).8
L-lysine is required for the manufacture of collagen, the main protein of the connective tissue matrix that forms tendons, ligaments, and bone, as well as the intracellular cement that holds skin and other tissues in place. L-lysine supplementation may help to boost collagen production.9 A topical preparation containing 15% L-lysine helped wounds heal faster than a standard or placebo treatment.10
L-lysine and other essential amino acids are critical to bone health.11 L-Lysine may help to increase the absorption of calcium. In one human study of people with decreased bone mineral density, supplementation with calcium bound to L-lysine significantly increased the bioavailability of calcium.12
Carnitine is a vitamin-like compound synthesized in the body from L-lysine. Carnitine is responsible for the transport of long-chain fatty acids into the energy-producing mitochondria within cells. L-lysine supplementation can increase blood levels of carnitine, indicating L-lysine increased carnitine synthesis.13
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