Lysine: Definition, Function, and Sources

Lysine is an essential amino acid that plays a crucial role in protein synthesis, collagen formation, and nutrient absorption in the body. It is unable to be produced by the body itself, so it must be obtained through dietary sources. The recommended daily intake of lysine for adults is around 30 mg per kilogram of body weight.

The main function of lysine is to support the growth, repair, and maintenance of tissues in the body. It is particularly important for the production of collagen, a protein that provides structure to the skin, bones, and blood vessels. Lysine also helps in the absorption of calcium and the synthesis of carnitine, a molecule involved in energy metabolism.

The main benefit of lysine is its role in promoting healthy skin, bones, and connective tissues. It may also have antiviral properties and can help support the immune system. However, excessive intake of lysine through supplements may lead to adverse effects such as gastrointestinal distress or kidney damage, so it is important to follow recommended dosages and consult with a healthcare professional if considering supplementation. is a reader-supported platform. Purchases made through our links may earn us a commission at no extra cost to you.

What is lysine?

Lysine, also known as L-lysine, is an essential amino acid that is vital for the human body. It cannot be synthesized by the body and must be obtained through diet or supplements. Lysine is classified as an α-amino acid, which means it is a building block of proteins.

One of the key functions of lysine is its role in protein synthesis, specifically in the crosslinking of collagen polypeptides. Collagen is a structural protein that provides strength and support to various tissues in the body, including skin, bones, and tendons. Lysine plays a crucial role in the formation and maintenance of collagen, contributing to healthy skin and connective tissues.


According to a study published in Integrative and Comparative Biology by V.J. Iseri and K.C. Klasing from the University of California, lysine is also significant in the functioning of the immune system. The study found that when the cells were fighting off the bacteria, the levels of lysine in certain proteins of their immune system went up significantly. In simple terms, lysine plays an important role in helping the immune system function, especially when it’s actively fighting off an infection.

When it comes to dietary sources, lysine can be found in a variety of foods. Animal-based sources such as meat, fish, and dairy products are rich in lysine. Legumes, including beans, lentils, and soy products, are also good sources of lysine for vegetarians and vegans.

What is the difference between lysine and L-lysine?

Lysine and L-lysine are both amino acids, which are the building blocks of proteins. Lysine is an essential amino acid, meaning it cannot be synthesized by the body and must be obtained from the diet. Lysine is important for overall health and is involved in various physiological processes, including protein synthesis and tissue repair.

L-lysine, on the other hand, is the biologically active form of lysine. It plays a specific role in metabolic processes such as the synthesis of collagen, a protein that provides structure and support to tissues like skin, tendons, and bones. L-lysine also plays a role in the production of enzymes, hormones, and antibodies, thereby contributing to immune function.

What is the chemical structure of lysine?

The chemical structure of lysine consists of an α-amino group (-NH2) and an α-carboxylic acid group (-COOH) attached to the α-carbon, which is a chiral carbon.

lysine chemical structure
What is the chemical structure of lysine?

Lysine is an essential amino acid encoded by the codons AAA and AAG. Its chemical formula is C6H14N2O2 and it has a molecular weight of 146.19 g/mol.

The structural formula of lysine is H2N-CH2-(CH2)3-CH(NH2)-COOH, with the α-amino group attached to the α-carbon and a side chain consisting of four carbon atoms. Lysine is classified as a basic, charged, and aliphatic amino acid.

How is lysine metabolized in the body?

Lysine is metabolized in the body through a series of steps. When lysine is consumed through the diet, it undergoes catabolism, starting with the formation of saccharopine. Saccharopine is then converted to 2-aminoadipic acid, which is further metabolized through decarboxylation to a series of CoA esters. Ultimately, this process leads to the production of acetyl-CoA.

Lysine catabolism primarily occurs in the liver, where the metabolic pathways are active. The liver plays a crucial role in breaking down lysine and converting it into energy sources like acetyl-CoA. Additionally, the intestinal microflora also contribute to lysine metabolism by synthesizing and making lysine available in the body.

How does lysine function as an amino acid in the body?

Lysine functions as an essential amino acid in the body, playing a crucial role in protein synthesis and contributing to various bodily functions. During protein synthesis, lysine is incorporated into polypeptide chains, helping to create the diverse range of proteins needed for biological processes.

lysine amino acid
How does lysine function as an amino acid in the body?

It also plays a vital role in the crosslinking of collagen, a structural protein found in our skin, bones, and connective tissues, maintaining their integrity and strength.

Additionally, lysine facilitates the absorption of essential mineral nutrients, such as calcium, by aiding their transport across cell membranes. For example, lysine is necessary for the production of collagen, which is important for wound healing. It is also involved in the synthesis of enzymes and hormones, such as insulin.

Furthermore, lysine helps maintain a healthy immune system by aiding in the production of antibodies. Ensuring an adequate intake of lysine through lysine-rich food sources supports optimal protein synthesis and overall bodily functions.

What role does lysine play in a well-rounded diet?

Lysine is an essential amino acid that plays a vital role in maintaining a well-rounded diet. It is involved in multiple physiological functions within the body. Specifically, lysine is necessary for protein synthesis, the production of enzymes, hormones, and antibodies, and the absorption of calcium and other essential minerals, promoting bone health.

Furthermore, lysine supports the production of collagen, a structural protein crucial for the integrity of connective tissues, including skin, tendons, and cartilage.

Numerous studies have highlighted the importance of lysine in a well-rounded diet. For example, a study conducted at the University of Maryland Medical Center found that lysine supplementation can help reduce the severity and duration of cold sores caused by the herpes simplex virus. Additionally, researchers at the University of California, Davis, have shown that lysine deficiency can lead to impaired growth and development in children.

To ensure an adequate intake of lysine, it is recommended to incorporate lysine-rich foods into daily meals. Good dietary sources of lysine include meat, poultry, fish, dairy products, legumes, and quinoa. By including these foods in one’s diet, individuals can support optimal health and maintain a well-balanced diet.

Can vegetarians get enough lysine through plant-based foods?

Yes, vegetarians and vegans can get enough lysine through plant-based foods. Sources of lysine in a plant-based diet include legumes like lentils and chickpeas, quinoa, pumpkin seeds, and tofu.

What are the health benefits of lysine?

The following are the health benefits of lysine.

  1. Cold sore treatment: Lysine supplementation at a dosage of 1,000-3,000 mg per day has been shown to reduce the frequency and duration of cold sore outbreaks.
  2. Enhanced immune function: Lysine plays a crucial role in supporting immune function by aiding in the production of antibodies and promoting the activity of natural killer cells.
  3. Collagen production: Lysine is a vital component in collagen synthesis, contributing to the strength and elasticity of connective tissues and promoting wound healing.
  4. Bone health: Lysine helps in the absorption of calcium and the formation of collagen, which are essential for maintaining strong and healthy bones.
  5. Anxiety and stress relief: Lysine supplementation has been found to reduce anxiety and stress levels, with studies suggesting a dosage of 1,500-3,000 mg per day.
  6. Improved athletic performance: Lysine aids in muscle repair and growth, and may enhance exercise endurance and recovery. A dosage of 1,500-2,000 mg per day is commonly used.
  7. Antiviral activity: Lysine has been shown to inhibit the replication of certain viruses, including herpes simplex virus (HSV), which causes cold sores and genital herpes.

What is the role of lysine in hormone regulation?

Lysine plays a vital role in hormone regulation by contributing to the synthesis and function of various hormones in the body. It acts as a precursor for the production of growth hormones, such as insulin-like growth factor 1 (IGF-1), which is crucial for growth and development.

Lysine also aids in the regulation of cortisol, a stress hormone that helps the body respond to stress and maintain homeostasis. Furthermore, lysine is involved in the production of sex hormones, including estrogen and testosterone, which are essential for reproductive health.

How does lysine help in treating cold sores?

L-lysine supplementation may be useful in preventing the recurrence of herpes simplex virus (HSV) infections, such as cold sores, according to a review article titled “Lysine for Herpes Simplex Prophylaxis: A Review of the Evidence” by Venthan J Mailoo and Sanketh Rampes.

The study found that L-lysine supplementation appears to be ineffective at doses less than 1 gram per day unless combined with a low-arginine diet. However, doses exceeding 3 grams per day seem to improve patients’ subjective experience of the disease, including the frequency and severity of outbreaks.

What is the maximum dosage of lysine for treating cold sores?

The maximum dosage of L-lysine for treating recurrent cold sores, as per a 1987 study by R S Griffith et al., published in the journal Dermatologica, is 1,000 mg (milligrams) taken three times a day, totaling 3,000 mg per day, for a duration of 6 months. This dosage was found to be effective in reducing the occurrence, severity, and healing time of HSV infections.

How effective is L-lysine for treating herpes outbreaks?

According to a 2005 study titled “Safety and effectiveness of an L-lysine, zinc, and herbal-based product on the treatment of facial and circumoral herpes,” a combination of L-lysine with botanicals and other nutrients was found to be effective in treating symptoms of facial and circumoral herpes.

In the study, 30 male and female participants were divided into two groups of 15 each. They were assessed based on 10 outcome measures such as tingling, itching, burning, tenderness, prickling, soreness, bump/swelling, small blister(s), oozing blister(s), and crusting. The participants also took before-and-after photographs of the lesions and kept a daily diary.

What are the benefits of L-lysine for skin and hair health?

L-lysine offers several benefits for skin and hair health.

  1. Promotes collagen synthesis, improving skin texture and reducing signs of aging.
  2. Enhances hair strength and thickness, promoting hair growth.
  3. Prevents hair loss by supporting healthy hair follicles.
  4. Maintains scalp health, reducing dryness and itchiness.
  5. Supports the production of elastin, a protein that gives skin its elasticity.
  6. Helps repair damaged skin cells and tissues.
  7. Boosts the production of keratin, a protein that strengthens hair strands.

How does lysine contribute to muscle growth and repair?

Lysine, as an essential amino acid, plays a crucial role in muscle growth and repair when consumed as part of a balanced diet.

  1. Protein Synthesis: Lysine is involved in the synthesis of muscle proteins, leading to muscle growth. It acts as a substrate for the production of myofibrillar proteins, which make up the structure of muscle fibers. Lysine helps in the translation of genetic information into muscle protein, facilitating muscle growth and repair.
  2. Collagen Formation: Lysine is vital for the formation of collagen, a protein that provides structure to muscles and connective tissues. Collagen is essential for the repair and regeneration of muscle tissues after exercise or injury. Lysine acts as a precursor for collagen synthesis, supporting the structural integrity of muscles.
  3. Nutrient Absorption: Lysine aids in the absorption of essential minerals like calcium and zinc. Calcium is necessary for muscle contraction and relaxation, while zinc is involved in muscle repair processes. Lysine helps optimize the absorption of these minerals, ensuring their availability for muscle function and repair.

Including lysine-rich sources in your diet, such as meat, fish, dairy products, and legumes, can help meet the lysine requirements for muscle growth and repair. Consuming approximately 1.2-1.6 grams of lysine per kilogram of body weight per day is recommended for individuals engaged in regular exercise or muscle-building activities.

What is the impact of lysine on cognitive functions?

Lysine has a positive impact on cognitive functions by enhancing memory and focus. This essential amino acid is involved in the synthesis of neurotransmitters such as serotonin and dopamine, which are crucial for cognitive processes.

Lysine also supports brain cell integrity by promoting the production of collagen, a protein that maintains the structure of brain cells. Additionally, lysine aids in the formation of acetylcholine, a neurotransmitter important for learning and memory.

How does lysine affect cholesterol levels?

Lysine affects cholesterol levels through multiple mechanisms. Firstly, lysine promotes the production of carnitine, which helps transport fatty acids into the mitochondria for energy production. This reduces the accumulation of cholesterol in the bloodstream.

Secondly, lysine inhibits the activity of enzymes involved in cholesterol synthesis, such as HMG-CoA reductase, leading to a reduction in cholesterol production. Lastly, lysine enhances the activity of enzymes involved in bile acid synthesis, which aids in the digestion and absorption of dietary fats, including cholesterol.

How does lysine affect blood pressure and cardiovascular health?

Lysine has a positive impact on blood pressure and cardiovascular health. It aids in the synthesis of nitric oxide (NO), a molecule that promotes blood vessel dilation. This vasodilation leads to improved blood flow and lowers blood pressure. Lysine also helps prevent plaque formation in the arteries, reducing the risk of cardiovascular diseases.

Furthermore, lysine reduces levels of homocysteine, an amino acid linked to heart disease. Good dietary sources of lysine include meat, fish, dairy products, and legumes. By incorporating lysine-rich foods into your diet, you can maintain healthy blood pressure and cardiovascular function.

What are the benefits of using lysine for canker sores?

Lysine can provide several benefits for canker sores.

  • Reduction of symptoms: Lysine can help reduce the pain, inflammation, and discomfort associated with canker sores by inhibiting the activity of arginine, an amino acid that can trigger outbreaks.
  • Speeding up the healing process: Lysine promotes faster healing of canker sores by increasing the production of collagen, a protein crucial for tissue repair and regeneration.
  • Prevention of future outbreaks: Lysine can help prevent recurrent canker sores by inhibiting the replication of the herpes simplex virus, which is often the underlying cause of these sores.

What are the side effects of L-lysine?

L-lysine is generally safe for most people when taken in appropriate doses, but there are potential side effects to consider.

  1. Gastrointestinal discomfort such as nausea, diarrhea, or stomach cramps.
  2. Rare allergic reactions include itching, swelling, or difficulty breathing.
  3. Abdominal pain with high doses.
  4. Kidney problems with high doses.
  5. Headache.
  6. Dizziness.
  7. Fatigue.

How much lysine should one take daily for general health?

The recommended daily allowance (RDA) for lysine varies depending on factors such as age, gender, and overall health. For general health, the RDA for lysine in adults is around 30 milligrams per kilogram of body weight. This means that a person weighing 70 kilograms would require approximately 2100 milligrams (2.1 grams) of lysine per day.


It can be obtained from various food sources such as meat, poultry, fish, dairy products, legumes, and certain grains. Consuming lysine-rich foods regularly is important to meet the daily lysine requirements. However, it is advisable to consult with a healthcare professional or registered dietitian to determine the specific lysine requirements based on individual needs and health goals.

How does a deficiency in lysine affect the body?

A deficiency in lysine can have a negative impact on the body by impairing protein synthesis and collagen formation. Lysine is an essential amino acid that plays a crucial role in these processes. Protein synthesis is vital for tissue growth, repair, and maintenance, while collagen formation is essential for the strength and structure of connective tissues, such as skin, tendons, and bones.

When there is not enough lysine in the diet, collagen production is reduced, leading to weakened connective tissues and impaired wound healing. For example, a deficiency in lysine can result in slower healing of cuts and wounds. Additionally, lysine deficiency can compromise the immune system, making individuals more susceptible to infections. For instance, a lack of lysine can make it easier for viruses like herpes simplex virus to replicate and cause cold sores.

What foods are high in lysine?

Foods that are high in lysine include:

  • Lentils (1 cup cooked contains approximately 2,478 mg of lysine)
  • Chickpeas (1 cup cooked contains approximately 2,523 mg of lysine)
  • Black beans (1 cup cooked contains approximately 1,508 mg of lysine)
  • Chicken (3 ounces cooked contains approximately 2,453 mg of lysine)
  • Turkey (3 ounces cooked contains approximately 2,521 mg of lysine)
  • Fish (such as salmon and tuna) (3 ounces cooked contains approximately 2,007 mg of lysine)
  • Yogurt (1 cup contains approximately 1,012 mg of lysine)
  • Cheese (such as parmesan and cheddar) (1 ounce contains approximately 542 mg of lysine)
  • Milk (1 cup contains approximately 221 mg of lysine)

What foods are high in lysine but low in arginine?

Foods high in lysine and low in arginine have a favorable ratio for individuals looking to increase lysine intake while minimizing arginine levels. Here are seven examples of high lysine low arginine foods:

  • Quinoa (1 cup cooked: 442 mg lysine, 120 mg arginine)
  • Lentils (1 cup cooked: 1772 mg lysine, 659 mg arginine)
  • Black beans (1 cup cooked: 2077 mg lysine, 938 mg arginine)
  • Chia seeds (1 ounce: 604 mg lysine, 162 mg arginine)
  • Pumpkin seeds (1 ounce: 593 mg lysine, 474 mg arginine)
  • Tofu (1/2 cup: 1540 mg lysine, 517 mg arginine)
  • Greek yogurt (1 cup: 1106 mg lysine, 607 mg arginine)

What are the general uses of lysine supplements?

Lysine supplements are commonly used for immune support, cold sore management, and collagen production. Lysine plays a crucial role in immune function, as it helps in the production of antibodies and supports the synthesis of immune-related enzymes.

Research has shown that lysine can reduce the frequency and duration of cold sore outbreaks by inhibiting the replication of the herpes simplex virus. Additionally, lysine is essential for collagen production, which is important for maintaining healthy skin, bones, and connective tissues.

What is the recommended daily dosage of lysine supplements?

The recommended daily dosage of lysine supplements varies depending on individual factors such as age, health condition, and specific needs.

Human adults using lysine supplements for cold sores typically take between 1000-3000 mg per day during an outbreak to help manage symptoms. The appropriate dosage of lysine supplement should be determined in consultation with a healthcare professional or veterinarian, taking into account these factors to ensure optimal efficacy and safety.

What is the recommended daily dosage of lysine supplements for cats?

For cats, l-lysine is often given to support their immune system and overall health, with a recommended dosage of around 250-500 mg per day.

How much L-lysine should be taken for weight loss?

The optimal daily dosage of L-lysine for weight loss varies based on individual factors, but a recommended starting dosage is 1,000-3,000 mg per day. L-lysine plays a role in the production of carnitine, which is involved in the metabolism of fatty acids.

By increasing the availability of carnitine, L-lysine may enhance the body’s ability to utilize stored fat as an energy source, thereby supporting weight loss. Additionally, L-lysine may help reduce feelings of hunger and promote satiety, potentially leading to decreased calorie intake.