🔑 Core Function

• Collagen synthesis: Vital for bone, skin, and connective tissue integrity.
• Carnitine production: Needed to make carnitine, which transports fatty acids into mitochondria for energy.
• ️ Immune support: Contributes to antibody and enzyme production.
• ⚖️ Calcium balance: Helps improve calcium absorption and may reduce urinary calcium loss.

🧬 Family & Essentiality

🌿 Plain-Language Summary

Lysine is one of the body’s core building blocks for proteins. Think of it as a structural specialist: it’s essential for collagen (skin, joints, bones) and for making carnitine, which moves fats into mitochondria for energy. It also supports immunity and calcium balance.

⚗️ Molecular & Chemical IDs

• Abbreviation: Lys / K
• Chemical formula: C₆H₁₄N₂O₂
• Structure: Basic amino acid with positively charged side chain

⚡ Functions

• ️ Structural: Collagen and elastin formation for skin, cartilage, and bone.
• Energy metabolism: Via carnitine synthesis → fatty acid transport into mitochondria.
• ️ Immune health: Supports antibody, enzyme, and hormone synthesis.
• ⚖️ Calcium handling: Enhances calcium absorption and retention.

🍽️ Absorption & Bioavailability

🇦🇺 Australian NRVs (NHMRC)

• Adults (≥19 yrs) EAR: ~30 mg/kg/day
• RDI: ~38 mg/kg/day

Values based on NHMRC/FAO/WHO amino-acid requirement data, expressed per kilogram body weight.

🥗 Food Sources

• Meat, poultry, fish
• Dairy (milk, cheese, yoghurt)
• Eggs
• Legumes (beans, lentils, soy), quinoa, amaranth

Tip: Combining grains + legumes improves lysine adequacy in vegetarian diets.

🧪 Testing & Monitoring

• Plasma amino acid profiling (specialist labs).
• ❌ Not part of routine GP pathology testing.

🔄 Interactions

• ➕ Works with vitamin C for collagen formation.
• ➕ Requires adequate iron, zinc, and vitamin B6 for protein metabolism.
• ⚠️ Deficiency risk in cereal-based diets → may contribute to growth delays, fatigue, anaemia.

🚨 Deficiency & Evidence

Deficiency

Possible in poorly diversified cereal-based diets; may affect growth, immune resilience, and protein quality.

Evidence Snapshot

• ✅ Established: Essential for protein synthesis, collagen, and carnitine production.
• ⚖️ Mixed/conditional: Supplemental lysine studied for reducing herpes simplex outbreaks; evidence inconsistent.