🔑 Core Function

• Energy supply: Provides fuel for muscles during exercise and fasting.
• Muscle repair: Supports recovery and protein balance, alongside leucine and isoleucine.
• Neurotransmitter balance: Competes with tryptophan and other large amino acids for brain uptake, influencing serotonin levels.
• Nitrogen balance: Important for muscle metabolism and tissue repair.

🧬 Family & Essentiality

🌿 Plain-Language Summary

Valine is one of the body’s fuel and endurance amino acids. As part of the BCAA trio, it helps muscles generate energy, recover after exercise, and maintain protein balance.

⚗️ Molecular & Chemical IDs

• Abbreviation: Val / V
• Chemical formula: C₅H₁₁NO₂
• Structure: Branched-chain, hydrophobic side chain

⚡ Functions

• Energy source: Oxidised in muscles for ATP during exercise.
• Muscle metabolism: Supports growth and tissue repair.
• Brain chemistry: Competes with tryptophan for brain transport → influences serotonin levels and fatigue perception.
• Nitrogen economy: Helps maintain nitrogen balance during metabolic stress.

🍽️ Absorption & Bioavailability

🇦🇺 Australian NRVs (NHMRC)

• Adults (≥19 yrs) EAR: ~13 mg/kg/day
• RDI: ~24 mg/kg/day

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

🥗 Food Sources

• Meat, poultry, fish
• Dairy products (milk, cheese, whey protein)
• Eggs
• Legumes, soy, peanuts, whole grains

Whey protein powders are especially rich in valine and other BCAAs.

🧪 Testing & Monitoring

• Plasma amino-acid profiling (specialist labs).
• ❌ Not a routine clinical test in Australia.

🔄 Interactions

• Works synergistically with leucine (muscle protein trigger) and isoleucine ⚡ (glucose regulation).
• ⚠️ Inborn error: Maple Syrup Urine Disease → defective breakdown of valine, leucine, isoleucine.
• Requires vitamin B6 as a cofactor for catabolism.

🚨 Deficiency & Evidence

Deficiency

Rare outside severe protein–energy malnutrition or metabolic disorders such as Maple Syrup Urine Disease.

Evidence Snapshot

• ✅ Established: Critical for muscle fuel, tissue repair, and nitrogen balance.
• ⚖️ Mixed: BCAA supplementation studied for reducing exercise fatigue and supporting recovery, but benefits are less clear if total protein intake is already sufficient.