Lysine
Also known as L-lysine, Lys
Lysine is an essential amino acid that the body cannot make, so it must come from food. It is needed to build proteins, form collagen, and absorb calcium, and it is the amino acid most often limiting in grain-based diets.
Why it matters
What it does in your body
- Protein building block
- Collagen formation and tissue repair
- Calcium absorption support
- Carnitine production for fat metabolism
Intake guidance
How much you need
The IOM sets the requirement at 38 mg/kg/day, about 2.7 g/day for a 70 kg adult. Any diet with enough total protein provides plenty.
What affects it
What affects your intake
Total protein intake
Adequate protein, especially from animal sources or legumes, easily meets lysine needs.
Grain-heavy or vegan diets
Cereals and grains are low in lysine, so plant-based eaters should include beans, lentils, and soy to balance intake.
Food processing
High-heat processing can reduce available lysine, though this rarely matters on a varied diet.
In practice
Good to know
Deficiency is uncommon among people who eat animal protein or legumes, but strict plant-based diets built mainly on grains can run low, so pairing grains with beans helps. Lysine supplements are commonly used to shorten or prevent cold sore (herpes simplex) outbreaks, and the evidence is mixed but generally low-risk. Beyond that, most people meet their needs from food.
Where to get it
Best food sources
The bottom line
Lysine is the amino acid vegans should watch, so include legumes and soy. Its main supplement use is for cold sores, where results vary.
Track lysine automatically
Lysine is one of the 92 nutrients Vora reads from a photo of your meal, so you can see where you stand without weighing or logging by hand.
Sources and method
The classification, roles, and guidance on this page come from the references below, drawing on the Institute of Medicine (now the National Academies) Dietary Reference Intakes and reputable nutrition science.
- Institute of Medicine (2005), Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids
This page is for general education, not medical advice. Reference intakes are population averages for healthy people and do not replace guidance from your doctor or a registered dietitian, especially if you are pregnant, managing a health condition, or considering supplements.