What it does in the body
- Muscle protein synthesis (BCAA)
- Energy substrate in skeletal muscle during prolonged exercise
- Blood glucose regulation via glucose transporter stimulation
- Hemoglobin synthesis
- Immune cell function and proliferation
How much you need (Daily Value)
| Group | Recommended | Source |
|---|---|---|
| Adult male | 20mg/kg/day (~1.4g for 70kg) | WHO/FAO/UNU |
| Adult female | 20mg/kg/day (~1.2g for 60kg) | WHO/FAO/UNU |
| Pregnancy | 25mg/kg/day | WHO |
| Children | 28-32mg/kg/day depending on age | WHO |
| Older adults | 20mg/kg/day; higher if sarcopenic | WHO/ESPEN |
Richest food sources
| Food | Amount | Where |
|---|---|---|
| Chicken breast (cooked) | 1.2g per 100g | global |
| Beef (lean, cooked) | 1.1g per 100g | global |
| Tuna (cooked) | 1.0g per 100g | global |
| Eggs (whole) | 0.7g per 100g | global |
| Soybeans (cooked) | 0.6g per 100g | east-asia |
| Lentils (cooked) | 0.4g per 100g | south-asia |
| Cottage cheese | 0.6g per 100g | europe |
| Spirulina (dried) | 3.2g per 100g | global |
If you don't get enough
Mild: Muscle fatigue, reduced exercise performance, delayed recovery
Moderate: Muscle wasting, impaired blood glucose control, depression, irritability
Severe: Severe muscle catabolism, neurological symptoms, immune dysfunction
Time to onset: Performance decrements within 1-2 weeks; clinical signs within 4-6 weeks of deprivation
Too much
Upper limit: No established UL; doses up to 20g/day used in studies without severe effects but long-term safety unclear
High doses may cause nausea, fatigue, and impaired coordination; excess BCAAs may worsen insulin resistance in some contexts
How well you absorb it
90-95% from animal proteins; 80-90% from plant sources
Helped by: Vitamin B6 (BCAA transamination cofactor), Adequate caloric intake, Co-ingestion with leucine and valine
Hindered by: Excess leucine (competitive inhibition of transport), Alcohol (impairs BCAA metabolism), Liver disease
Cooking & storage
Heat-stable amino acid; normal cooking preserves isoleucine content well. Extended high-heat processing (canning, UHT treatment) may reduce content by 5-10%.
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