Last reviewed by Editorial Team on August 18th, 2018.
What is L-Lysine?
L-Lysine or just Lysine, is one of the most important and essential amino acid that is required in the body. Essential amino acids occur mostly in form of stereoisomers. Stereoisomers exist in two forms which are identical to one another as mirror images. These forms are D-form and L-form. Lysine is present is L-form.
Even though it is a basic amino acid yet it is not produced by the body itself. It has to be obtained from external sources which include food and supplements. Lysine and other various amino acids are the basic building blocks of proteins. These proteins, in turn, are used in various processes.
Some of these processes which require lysine are in the development of immunity in the body against a number of diseases, helps in improving appetite and digestion. Lysine also boosts calcium absorption, increases the protein content in muscles and generates the production of hormones, antibodies, and various enzymes.
L-lysine molecular structure, weight, formula, class, chemical and other names for Lysine
Chemical name: L-2,6-diaminohexanoic acid
Other names: L-Lysine, L-Lysine Hydrochloride, Lisina
Drug class: This compound belongs to the class of organic compounds known as l-alpha-amino acids. These are alpha amino acids which have the L-configuration of the alpha-carbon atom.
Common ingredients of Lysine supplements
Active ingredient: L-Lysine Monohydrochloride
Inactive ingredients: gelatin(capsule), stearic acid, cellulose, rice flour, and Mg stearate
How does Lysine work?
Lysine is transformed into acetyl CoA, which is an essential component in the carbohydrate metabolism and in generation of energy. Lysine is the originator of the amino acid carnitine, which helps in the transportation of long chain fatty acids into the mitochondria for energy production and other various metabolic pathways.
As soon as Lysine is bound to a polypeptide structure, the initiation of biosynthesis of carnitine occurs. This is done by methylating one if the amino group’s present in lysine compound.
Furthermore, Lysine have an antagonist association with the amino acid arginine. Lysine competes with this amino acid for the purpose of absorption in the intestinal region, reabsorption in tubules of kidney, and movement across the plasma membrane.
Pharmacokinetics and biochemistry of Lysine
Lysine, an amino acid which has a basic character, positively charged at physiological pH and is extremely soluble in water. It has a molecular weight of 146.19 Daltons.
Lysine supplementations are available in oral dosage forms such as soft gelatin capsules. Once ingested, it is absorbed from the intestinal region into the enterocytes through the processes of active transport and transport from gut to the liver by means of portal circulation. As soon as lysine reaches liver, it links with other amino acids to assist in protein synthesis.
Catabolism also takes place in liver, where it undergoes condensation with ketoglutarate to form saccharopine. Sacchropine is transformed to L-alpha-aminoadipic acid semialdehyde, which is then ultimately is converted acetoaceyl-CoA. Lysine does not go through transamination. However, it is ketogenic and glycogenic and can assist in the formation of D-glucose, glycogen, lipids and as a result in the generation of energy.
Pharmacokinetic studies have demonstrated that lysine supplements have the absorption rate in a same way to that after digestion of proteins, suggesting supplementation is an effective and efficient means of correcting a dietary lysine deficiency.
Lysine is quickly transferred into muscle tissue within a time period of 5-7 hours after it is administered. This is more concentrated in the intracellular space of muscle tissue in comparison to the concentration of other amino acids. From this observation, we can assume that the muscle tissues may act as a reservoir for un-conjugated lysine in the body.
Research studies are still being conducted to collect data on other pharmacokinetic parameters including route of elimination, half-life, clearance, protein binding, and volume of distribution.
What are the benefits of Lysine supplements
Lysine has been used over years for many purposes. It has proven to be useful as a herbal product and is often put up for sale as an herbal supplement. Along with this, lysine is marketed as an alternative medicine product too.
Medicinal use of lysine hasn’t yet been approved by FDA and should not be substituted for a medical drug which has been prescribed by the doctor. But over time, a number of manufactures have formulated lysine in dosage forms which have enabled its use in more conveniently and removed the risk of contamination that was a major drawback in herbal formulations. Some of the benefits that are obtained by using L-Lysine are mentioned below:
L-Lysine in the treatment of herpes virus
Herpes simplex virus-1 causes the formation of cold sores (herpes). These are actually fluid-filled blisters which are visibly seen either on the lips or around the lips. The major route of transmission is through the infected saliva. When saliva comes in contact the virus accumulates on the skin and causes these blisters to develop.
A number of studies have verified that taking lysine on regular basis or more preferably on daily basis has decreased the occurrence of genital herpes and cold sores. This is mainly due to the anti-viral action of Lysine which blocks the activity or arginine. Arginine is also an amino acid which upholds the replication of herpes simplex virus.
Actually, even though arginine and lysine are both amino acids but they are antagonist to each other. This means, when the levels of arginine in body are high, lysine levels are less. Lysine acts on the HSV virus and halts the replication. In one of research study that had been conducted, the individuals who used L-lysine for treating the cold sores had found it to be very effective.
Other studies have shown that L-lysine have not only been useful in reducing the rate of outbreaks but also have drastically decreased the duration of time for which the blisters had appeared on the skin.
However, L-lysine has yet not been efficient in completely stopping the eruption of such cold sores. Alongside the treatment of cold sores which are caused by herpes simplex virus-1 (HSV-1), L-lysine have also been valuable in helping to alleviate the genital herpes which occur due to herpes simplex virus-2 (HSV-2) possibly due to the same mechanism.
L-lysine in the treatment of cancer
Scientists have been looking for natural cancer treatments which have the same effect as that of the conventional therapies including chemotherapy and other radiation. This is majorly due to negative effect these procedures have on healthy cells in addition to the diseased ones.
With time, new technologies and new products are being tested in order to discover more and more ways which can potentially target cancerous particularly malignant cells without killing the good ones. A study conducted at the Florida State University had observed the consequences of lysine conjugates on spoiled strands of DNA similar to those which were found in cancer.
Lysine works by locating a spoiled strand by identifying ‘cleavage’ and in turn allows the rest of the strand to tear apart. This cell is usually not repairable and hence progresses towards apoptosis i.e. suicidal death of cells. The cancer killing capability that lies in lysine conjugates is only triggered when exposed to specific type of light.
This allows the researchers, scientists or any doctors involved to inject or place the treatment in a region where the cancer cells are most concentrated and active. This method has increased the rate of destroying cells from 25% to 90%.
L-lysine in the treatment of anxiety and other psychological problems
L-Lysine has been useful in reducing depression and other anxiety problems to a great extent. Intake of Lysine improves the absorption of calcium in body in turn it has proved to be beneficial in patients suffering from anxiety. Moreover, L-Lysine acts as an antagonist to the serotonin receptor. It binds to the serotonin receptors and put a stop to anxiety responses. There are a number of responses which occur due to stress including diarrhea.
Besides anxiety, L-Lysine also has demonstrated being useful in the people who are suffering from Schizophrenia. Here in such cases, it is necessary to continue the conventional therapy along with the intake of L-lysine. This combination helps to decrease the negative impact and general symptoms of Schizophrenia. Studies are still being conducted to determine the dosing and long term effects.
L-Lysine for diabetes-related problems
Over years, scientists have worked on diabetes and in its context to the presence of advanced glycation end metabolites which are termed as AGEs These advance glycation end metabolites are responsible for aging process in human beings and are present in a large quantity in diabetic patients.
These products are occupied in many diabetes associated problems thus provoking scientists to search and study over therapies that involve halting the AGEs from accumulating in large numbers. L-lysine have shown its effect towards the prevention of formation of advanced glycation end metabolites by avoiding the specific paths of glycation through which these products are generated and in turn helping to hold back infection.
L-Lysine as aids in calcium absorption
As mentioned above, L-lysine aids in Ca absorption in gut. The more the calcium absorbed the less the people will be at risk for developing osteoporosis and other joint disorders. It has been recommended to people who are having brittle bones. According to a study conducted, a total of 30 subjects were selected. 15 out of which were osteoporetic and 15 normal healthy women.
They were then given acute calcium loading dose. Half of these were given l-Lysine supplements. In the results obtained, the control group to which no lysine supplements were given had shown a diminished absorption of calcium. This was analysed through urine sampling.
Besides treating bone problems, calcium consumption in suitable amounts is concerned with lowering the risk of cancer, healthy weight, PMS symptom reduction, better dental health, improved nerve transmission and decreasing the chances of diabetes.
Moreover, it has been observed that those athletes who take L-Lysine on regular basis have shown better performance. This is due to the fact that there will be more Ca absorption hence better muscle movement.
L-Lysine for improvement of the functions of the heart
Low-density cholesterol (LDL) accumulates in the walls of arteries resulting in the hardening and narrowing of the lumen. This is known as atherosclerosis. When the arteries are hardened or the lumen decreases, the blood flow either is slowed down or is completely blocked. This increases the chances for the patient to suffer from heart attack.
Lysine generates carnitine in the body, which has a major function in using up the the fatty acids and LDL cholesterol. another benefit that is obtained by using L-lysine in combination with calcium, there is a reduction in the levels of lipoprotein-A (LPA).
LPA acts as a carrier to LDL in the blood. This means that the levels of LPA in blood are directly related to the risk of developing of plaque formation or clogging up of arteries. This, in turn, leads to a greater risk of developing diseases, stroke and even erectile dysfunction.
What are the side effects of taking lysine supplements
Even though lysine have got the approval by Food Drug Administration (FDA) for being used in any disease or condition but still it has not been completely assessed for its complete profile of safety, effectiveness and purity levels. Besides a few, all possible side effects or advantages are still to be studied. Moreover, yet no regulated marketing standards have been set up for such compound. Some of the side effects are:
- stomach pain
- difficulty breathing
- swelling of your face
Overdosage and toxicity of L-lysine
L-lysine supplementation, when taken in high doses greater than 10-15 g daily, have caused gastrointestinal upset, including nausea, abdominal cramps and diarrhea.
L-Lysine and allergic reactions
Patients can develop hypersentivity against medications. In the same manner individuals might become allergic to lysine supplement. Features of an allergic reaction can be as small as skin rashes, redness, hives to as large as anaphylaxis, shock.
L-lysine and formation of gallstones
Gallstones are solid substances which are hard in nature and are formed in the gallbladder. The formation of these stones has been painful for the patient. One of the major causes of formation of gallstones is due to cholesterol.
Using cholesterol lowering drugs for a prolonged time period leads to the accumulation of cholesterol in the bile in an attempt to remove the cholesterol. n a similar way, L-Lysine possesses cholesterol lowering property. Taking Lysine in high doses can cause the formation of gallstones.
L-lysine and abdominal cramps and diarrhea
No mechanism has yet been found but consumption of lysine in high doses has caused the patient to suffer from abdominal cramps and diarrhea.
L-Lysine interaction with arginine
Arginine is another amino acid that is present in the body in variable amounts. Presence of lysine in large amounts in the body has decreased the levels of arginine. Besides the role of arginine in the progression and spread of herpes virus, it has a vital function in maintaining a healthy normal system of body.
Arginine is converted into nitric oxide which is important to keep the blood vessels dilated to ensure a normal blood flow. Along with this arginine acts as a stimulator for growth hormones, insulin and various other substances in body.
The Food and Nutrition Board (FNB) of the U.S. Institute of Medicine set Recommended Dietary Allowances (RDAs) for essential amino acids in 2002. For lysine, for adults 19 years and older, 38 mg/kg body weight/day.
L-Lysine dietary sources
The nutritional requirement per day, in milligrams of lysine per kilogram of body weight, is: infants (3–4 months) 103 mg/kg, children (2 years) 64 mg/kg, older children (10–12 years) 44 to 60 mg/kg, adults 12 mg/kg. For a 70 kg adult, 12 milligrams of lysine per kilogram of body weight is 0.84 grams of lysine. Recommendations for adults have been revised upwards to 30 mg/kg.
Good sources of lysine are high-protein foods such as eggs, meat (specifically red meat, lamb, pork, and poultry), soy, beans and peas, cheese (particularly Parmesan), and certain fish (such as cod and sardines).
Lysine is the limiting amino acid (the essential amino acid found in the smallest quantity in the particular foodstuff) in most cereal grains, but is plentiful in most pulses(legumes). A vegetarian or low animal protein diet can be adequate for protein, including lysine, if it includes both cereal grains and legumes, but there is no need for the two food groups to be consumed in the same meals.
A food is considered to have sufficient lysine if it has at least 51 mg of lysine per gram of protein (so that the protein is 5.1% lysine). Foods containing significant proportions of lysine include:Infants (3-4 months old): 103mg/kg per a day:
- Fish: 9.19%
- Beef, ground, 90% lean/10% fat, cooked: 8.31%
- Chicken, roasting, meat and skin, cooked, roasted: 8.11%
- Azuki bean (adzuki beans), mature seeds, raw: 7.53%
- Milk, non-fat: 7.48%
- Soybean, mature seeds, raw: 7.42%
- Egg, whole, raw: 7.27%
- Pea, split, mature seeds, raw: 7.22%
- Lentil, pink, raw: 6.97%
- Kidney bean, mature seeds, raw: 6.87%
- Chickpea, (garbanzo beans, Bengal gram), mature seeds, raw: 6.69%
- Navy bean, mature seeds, raw: 5.73%
Requirements and dosage of L-Lysine
- Toddlers (2 years old): 64mg/kg per a day
- School-going children: 58mg/kg per a day
- Adults (30+ years old): 30-35 mg/kg per a day
Intake of Lysine in a characteristic Western diet is 40-180mg/kg per a day with the upper range till 300-400 mg/kg per a day.
According to FDA, the suggested intake of Lysine is 1000 mg per a day.
It is advised to have a daily dose of up to 3 grams is harmless for therapeutic purposes when administered in separate in three different doses.
In certain conditions, the patients may require Lysine intake for a chronic period at a higher dose.
Such as in herpes patients, patients can advised to take Lysine up to 9 grams per day during an eruption phase.
What if I don’t take enough Lysine?
Taking Lysine either via food sources or through taking supplements is necessary. Vegans who entirely consume vegetables as their food are more prone of developing lysine deficiency. These typical symptoms of this lysine deficiency are as below:
- decreased appetite
- unnecessary loss of hair
- agitation, mood swings
- bloodshot eyes
- kidney stones
- stunted growth
- reproductive disorders
- nausea, dizziness
- lack of focus.
What drugs can interact with Lysine supplements
Supplements are formulated to provide a larger population with greater benefit. However, each individual is influenced by the medication in a different way from another. Each patient has its own body needs and may be already using some other drugs or substances n order to attain a specific therapeutic outcome. When Lysine is administered it shows interaction in the following situations:
If the patient is already taking calcium by means external sources including supplements, Lysine ingestion will accumulate and increase the plasma levels of calcium in the body. Excessive accumulation of calcium in blood is termed as hypercalemia. Excessive thirst, urination, lowered pain threshold, nausea and gastrointestinal upset majorly constipation.
Besides these, hypercalcemia can more seriously cause increased chances of heart diseases including hypertension or atherosclerosis.
According to the studies conducted on animals, it has been seen that lysine and aminoglycoside antibiotics both bind to the same membrane vesicles present on the brush border lining of the small intestine.
When only a limited number of drug molecules bind to such membrane vesicles, it is not possible for them to move from side to side in intestine for the purpose of absorption or digestion. This mechanism has decreased the effectiveness of the drugs and may cause toxicity.
Aminoglyoside Antiobiotics include kanamycin, amikacin, tobramycin, gentamycin and neomycin.
Gastrointestinal agents (5-HT4 agonist):
This interaction is characterized as a minor interaction still studies are being conducted on human and animals both. It has been suggested that Lysine supplements inhibit the effects of these agents.
These drugs have their effect by acting on the serotonin receptor and decreasing the intestinal peristalsis, prevent gastric emptying but simultaneously increase the chances of esophageal reflux. This interaction has been more prominent with prucalopride and tegaserod.
In which conditions Lysine supplements are contraindicated
Using lysine in certain conditions may bring about unwarranted effects. Some of these conditions are:
Hyperlysinemia or lyperlysinuria
Some people are genetically abnormal and may have uncontrolled production of lysine in the body. This leads to a condition known as hyperlysinemia, which are increased levels of lysine in blood.
Another possible condition due to certain factors including genetic or any underlying disease is the excessive loss of lysine in urine. This is termed as hyperlysinuria. In both conditions, intake of lysine from external sources such as supplements is contraindicated.
Liver and Kidney Problems
Lysine is not normally produced in the body. It has to be consumed via some external sources. It has been observed that it is metabolized by liver enterocytes and possible excreted through kidney. In recent studies, it has been seen that due to presence of kidney problems the lysine starts to build up in tubular nephrons. In a severe case as reported the patient had developed Fanconi syndrome along with tubulointerstitial nephritis.
Breastfeeding and Pregnancy:
Based on the results obtained from some studies, when lysine is given to pregnant patients who are already using other vitamin or mineral supplements such as iron, it has been observed that the levels of hemoglobin increases rapidly as compared to those who are kept on control and not given any other supplement.
Increased hemoglobin eventually means more number of red blood cells. This in turn increases the viscosity of blood, thickening its consistency. When the blood becomes thick, possibility of formation of clot occurs. Therefore those women who are either pregnant or breast-feeding their babies, they should consult their healthcare provider before taking these lysine supplements.
Use of L-Lysine in animal feed
Lysine production for animal feed is a major global industry, reaching in 2009 almost 700,000 tonnes for a market value of over €1.22 billion. Lysine is an important additive to animal feed because it is a limiting amino acid when optimizing the growth of certain animals such as pigs and chickens for the production of meat.
Lysine supplementation allows for the use of lower-cost plant protein (maize, for instance, rather than soy) while maintaining high growth rates, and limiting the pollution from nitrogen excretion. In turn, however, phosphate pollution is a major environmental cost when corn is used as feed for poultry and swine.
Lysine is industrially produced by microbial fermentation, from a base mainly of sugar. Genetic engineering research is actively pursuing bacterial strains to improve the efficiency of production and allow lysine to be made from other substrates.
L-Lysine storage requirements
Unlike the other amino acids, lysine is not stable in powder form and is hygroscopic in nature. It is thus required to keep the raw material of lysine at a temperature below 0°C.
Once formulated, the tablets must not be exposed of to a higher temperature and direct contact with sunlight should be avoided. Humidity content should not be very high.