Lysine
amino-acidAn essential amino acid critical for collagen synthesis, calcium absorption, and antiviral immune function.
Definition
An essential amino acid critical for collagen synthesis, calcium absorption, and antiviral immune function. Limiting amino acid in most cereals/grains. DV is ~51mg/kg body weight. Found in meat, legumes, and dairy.
What Is Lysine?
Lysine is an essential amino acid that the human body cannot synthesize and must obtain from dietary sources. It is a positively charged (basic) amino acid at physiological pH, alongside arginine and histidine. Lysine is particularly notable because it is the first limiting amino acid in most cereal grains, meaning grain-based diets are often deficient in lysine unless complemented with legumes or animal proteins. The RDA for lysine in adults is 38 mg per kilogram of body weight per day, making it one of the amino acids with the highest recommended intake.
Key Functions
Lysine is involved in several critical biological processes:
- Collagen synthesis: Lysine is essential for the synthesis and cross-linking of collagen and elastin, the structural proteins that provide strength and flexibility to skin, bones, tendons, and cartilage. It is hydroxylated to form hydroxylysine, a unique component of collagen not found in other proteins.
- Carnitine production: Lysine, along with methionine, is a precursor to L-carnitine, a compound essential for transporting long-chain fatty acids into mitochondria for energy production.
- Calcium absorption: Lysine enhances intestinal calcium absorption and reduces calcium excretion in the urine, contributing to bone density and reducing the risk of osteoporosis.
- Immune support: Lysine is necessary for the production of antibodies and supports the maintenance of adequate immune responses.
- Antiviral properties: Lysine has been studied for its ability to inhibit the replication of herpes simplex virus (HSV) by competing with arginine, which the virus requires for replication.
Food Sources
Animal proteins are the richest sources of lysine. Plant-based sources are generally lower, with legumes being a notable exception:
- Beef (cooked): approximately 3.1 g per 100 g
- Chicken breast: approximately 2.9 g per 100 g
- Tuna (canned): approximately 2.8 g per 100 g
- Lentils (cooked): approximately 0.9 g per 100 g
- Parmesan cheese: approximately 3.3 g per 100 g
- Quinoa (cooked): approximately 0.4 g per 100 g (one of the best lysine-containing grains)
Vegetarians and vegans should ensure adequate lysine intake by combining legumes with grains and consuming sufficient total protein.
Top Food Sources
| # | Food | Amount per 100g |
|---|---|---|
| 1 | Egg, white, dried, stabilized, glucose reduced | 7,4g |
| 2 | Egg, white, dried, powder, stabilized, glucose reduced | 7,2g |
| 3 | Egg, white, dried | 6,8g |
| 4 | Soy protein isolate, potassium type | 6,8g |
| 5 | Soy protein isolate | 6,8g |
| 6 | Egg, white, dried, flakes, stabilized, glucose reduced | 6,7g |
| 7 | Seal, bearded (Oogruk), meat, dried (Alaska Native) | 6,4g |
| 8 | Whale, beluga, meat, dried (Alaska Native) | 5,8g |
| 9 | Fish, cod, Atlantic, dried and salted | 5,1g |
| 10 | Seaweed, spirulina, dried | 5,0g |
Related Terms
Amino Acid
The building blocks of protein.
Complete Protein
A food source containing all 9 essential amino acids in adequate amounts.
Calcium
The most abundant mineral in the body, essential for bone and teeth health, muscle function, and blood clotting.
Threonine
An essential amino acid required for the biosynthesis of glycine and serine, important for collagen and elastin production and immune function.