Nutrient glossary
What is lysine?
Lysine builds collagen and carnitine and is the amino acid grain-based diets run lowest on.
Reviewed 20 July 2026. General information, not medical advice.
The short version
Lysine cross-links collagen, forms the fat-transporter carnitine and helps absorb calcium. It is the classic limiting amino acid: grains carry little, which is why beans-plus-rice style pairings exist in almost every food culture.
Meat, fish, dairy and especially legumes are rich in it, so plant-based eating that includes beans, lentils or soy covers lysine without thought.
Daily reference
2.3 g a day
The adult requirement is about 30 mg per kg of body weight a day; legumes are the plant answer.
This is the fixed adult reference used across these pages. In the app, your amount adjusts to your body and way of eating.
Best food sources of lysine
| Food | Per serving | Per 100g |
|---|---|---|
| Chicken Breast | 4.43 g | 2.6 g |
| Ribeye Steak | 4.08 g | 2.72 g |
| Sirloin Steak | 3.74 g | 2.49 g |
| Roast Chicken | 3.44 g | 2.46 g |
| Tuna Steak | 3.33 g | 2.56 g |
| Duck Breast | 3.28 g | 2.34 g |
| Halibut | 3.25 g | 2.32 g |
| Pork Chop | 3.11 g | 2.39 g |
Common questions
- Does lysine help with cold sores?
- Evidence is mixed: some trials show fewer outbreaks at 1 to 3 g a day, others show nothing. It is safe, but not established treatment.
- Why do grains and beans complement each other?
- Grains run low on lysine but fine on methionine; beans are the reverse. Together across a day they form complete protein.