# lysine

/ˈɫaɪsin/ (US) · CEFR C1 · Noun

Source: https://englishreference.com/word/lysine
Updated: 2026-05-31

## Definition

an amino acid that your body needs to build proteins but cannot make on its own. You must get it from your diet, especially from meat and dairy.

For teachers: an essential amino acid that is a fundamental building block of proteins. It contains a side chain with a primary amine group, which is critical for various metabolic processes and structural integrity in the body.

## Examples

- Lysine is found in high amounts in chicken and eggs.
- Because the human body cannot synthesize lysine, it is necessary to include lysine-rich foods like beans and lentils in the daily diet.
- The deficiency of lysine in certain plant-based diets can lead to a limiting amino acid profile, where the lack of this specific nutrient restricts the body's ability to utilize other available proteins effectively.

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