What is Lysine?
Lysine is one of nine essential amino acids which cannot be produced by the body and needs to be obtained from the diet.
Lysine is needed for growth and tissue repair and many other functions within the body.
Amino acids come in L forms which is the natural type found in food and D forms which is the synthetic form produced in a lab. There is also a DL form which includes both the natural and synthetic form. Each type or form has a different effect within the body.
Health Benefits of Lysine
Helps absorb essential minerals
Lysine helps absorb key nutrients which includes calcium, iron and zinc. It also helps with the production of carnitine, a natural nutrient that helps support fat metabolism and energy production.
Helps with collagen
Lysine is involved in the synthesis of collagen which is essential for the connective tissues such as the bones, skin, tendons and cartilage. Collagen is also needed for good bone health. Some studies show that lysine as well as copper are essential for collagen production and a deficiency prevent collagen production. Due to lysines role in collagen production it may help prevent many diseases as they are usually linked to a collagen deficiency. A healthy immune system is highly dependent on healthy collagen production. [R]
Lysine may have anti-mucositis properties. Mucositis is a condition characterized by sore inflamed mouth or gut and common in cancer patients receiving chemotherapy.
Radiation and chemotherapy are linked to mucosal sores and inflammation, often found in the mouth. Lysine may be useful in healing mucosal wounds through its role in supporting collagen production.
Supports bone health
Lysine supports bone health as it is has an important role in the synthesis of collagen. It also helps absorb calcium, a major mineral needed for bone health. As people get older osteoporosis risk increases especially if there is a deficiency in vitamin D3 and or calcium. Lysine has an essential function in helping to absorb calcium in the intesines and may be potentially useful for those with osteoporosis along with other cofactors for bone health.
Promotes hair growth
Lysine is needed for healthy hair growth and this amino acid can be found in the hair roots. A deficiency of lysine can cause hair loss.
Lysine can promote better hair growth by nourishing the roots, increasing volume and improving hair shape.
May help with herpes infection
Lysine may prevent and fight against herpes simplex viruses (HSV) which is likely due to competing with arginine for absorption and release in to cells. By inhibiting arginine uptake, lysine has shown to have some promising potential against herpes infection and may inhibit the re-emergence of herpes infection. Cold sores which may result from and HSV infection have also shown to reduce with lysine supplementation.
Lysine is often added to lip balms and ointments because it is believed to help treat cold sores caused by the herpes simplex virus. Cold sores are a common viral infection that causes painful blisters on or around the lips, and lysine is thought to help prevent the virus from replicating and spreading.
Lysine may help with IBS
Irritable bowel syndrome IBS has been linked to stress which may be a major factor in the symptom of diarrhoea. Studies have shown that L-lysine and 5HTP can reduce diarrhoea symptoms by inhibiting the stress response that causes it. [R] [R] [R]
Excess zinc may be another factor in IBS related diarrhoea. Lysine intake increases calcium uptake which can reduce zinc levels and may be another mechanism through which diarrhoea is significantly reduced. Lysine also increases zinc absorption. Histidine is another amino acid that seems to have this effect as it helps transport zinc.
Needed for neurotransmitter and hormones
Lysine has an important function of supporting the synthesis of neurotransmitters and hormones.
Lysine acts as precursor of glutamate in the central nervous system.
Supplementation with lysine has been shown to reduce chronic anxiety in people with lysine deficiency. Studies have shown that supplementation with lysine and arginine can be helpful for people with mental stress and anxiety. [R]
Lysine acts as a partial serotonin receptor 4 (5-HT4) antagonist and has shown to decrease stress response in the brain and gut and help balance mood and reduce anxiety. It has also shown to reduce cortisol levels. [R]
Lysine can stimulate growth hormone (GH) release when infused intravenously or ingested orally. Arginine and ornithine also have the same effect.
Lysine increases the calming neurotransmitter gamma-amino butyric acid (GABA) which can reduce symptoms of stress and anxiety. [https://www.jhrr.org/article.asp?issn=2394-2010;year=2016;volume=3;issue=3;spage=92;epage=97;aulast=Vuvor]
Agonist / Synergist
Minerals> Ca, Zn, Fe
Lysine increases absorption of calcium
Lysine increase iron uptake – iron rich foods such as meat and fish also contain lysine
Lysine increases absorption of zinc Lysine has been shown to form a bond (ligand) in the intestines which increases serum zinc levels
Lysine is needed for carnitine production [R]
Lysine is needed for GABA synthesis
Antagonists
Amino Acids Arginine, cysteine
Lysine competes with arginine as they share the same amino acid transporters and has been shown to block arginine transport in vitro [https://pubmed.ncbi.nlm.nih.gov/17235609/]
Food Sources of Lysine
Lysine is found in in many animal based foods high in protein such as red meats, fish, and dairy products. Lysine is found in red meat, pork, poultry, cheese (parmesan), cod, sardines and eggs. Plant based food source of lysine can be found in soybeans such as tofu, isolated soy protein, tempeh, spirulina and fenugreek seeds.
Recommended Daily Allowance
Adults need around 30mg to 38mg per kg of body weight per day from dietary intake for optimal functioning.
The recommended dietary allowance (RDA) for lysine is around 38 mg/kg of body weight per day for adults.
Children need more amino acids that adults as their body is still developing. The recommended daily amount for children over the age of three increases by 10% to 20% more than what is needed by adults. For infants the amount required increases by 150% more than what is needed by adults.
The requirements may change on individual basis and highly dependent on existing health.
Lysine Supplementation
Lysine can be found in the form of capsules, powder and tablets. It can also be found in ointments and lip balms.
Lysine is commonly available as L-lysine which is the biologically active form of the amino acid containing L-isomer.
Most lysine supplements recommend intake of between 500 mg to 6,000 mg per day in divided doses.
Studies have shown that a dose between 500 to 3,000mg per day may be useful for treating cold sores.
Lysine supplements are usually available in a range of 500 to 1,000mg.
As a food supplement it is recommended to take 1000 mg per day with food dividing doses to address any deficiencies.
A lower dose is suitable for maintenance.
Taking single amino acid supplements are not always recommended and may be harmful for those with damaged liver or kidneys.
The safe upper limit for lysine intake from supplements is not well established. However, doses up to 3 grams per day have been used in research studies without significant side effects in healthy individuals. As with any supplement, it is always recommended to consult with a healthcare professional before taking lysine supplements.
Deficiency Symptoms of Lysine
Deficiencies of lysine are unlikely as it is available in most protein based foods.
Signs and symptoms of lysine deficiency include:
- Hair loss
- Fatigue
- Poor concentration
- Irritability
- Nausea
- Red eyes
- Anorexia
- Inhibited growth
- Calcium deficiency or low uptake
- Low intake of lysine
- Protein restricted diets
Lysine deficiency causes include:
Toxicity Symptoms of Lysine
Signs and symptoms of lysine toxicity include:
- Increased risk of gallstones
- Kidney problems
- High cholesterol
Causes of lysine toxicity include:
- High lysine intake
- Hyperlysinemia*
Hyperlysinemia is a condition where there is a high blood level of lysine and is caused by a deficiency of the enzyme needed to break down lysine. Most people with high lysine levels may not be aware of their condition as it rarely shows any symptoms. In rare cases hyperlysinemia can cause intellectual disability or behavioural problems.
High doses of L-lysine, up to 1000 mg (1g) is only recommended for adults. They should be avoided by pregnant or lactating women, children, people with kidney diseases and human immunode¬ficiency virus (HIV) or acquired immunode¬ficiency syndrome (AIDS).