L-tyrosine
Catecholamine precursor with RCT signal for cognitive performance under acute stress (cold, sleep deprivation, high cognitive load).
Why
L-tyrosine is the precursor for dopamine, noradrenaline and adrenaline, produced from phenylalanine. Multiple small military and laboratory RCTs report cognitive-performance preservation under acutely-stressful conditions (cold exposure, sleep deprivation, multitasking) at 100–300 mg/kg single doses. Less effective in non-stressed adults, the effect is most consistent when catecholamine demand is elevated.
How it works
Provides substrate for tyrosine hydroxylase, the rate-limiting enzyme in catecholamine synthesis. Under acute stress, catecholamine release rates can exceed dietary substrate availability, transiently depleting catecholamines, tyrosine supplementation rescues this.
Expected onset · Acute effect within 60–90 minutes
How to take
Dosage
Acute stress: 100–300 mg/kg as single dose 60 min before stressor (~7–22 g for a 75 kg adult). Lower daily-use doses: 500–2,000 mg.
Timing
60 minutes before anticipated stress; on empty stomach for absorption
On the label
'L-tyrosine' or 'N-acetyl-L-tyrosine' (NALT), NALT claims better solubility but has weaker evidence base. Stated grams per dose.
Ideal for
Adults with anticipated acute cognitive stress (high-stakes presentation, exam, military or first-responder scenario, sustained high cognitive load); not for chronic supplementation.
Safety
Evidence
Jongkees 2015 systematic review: tyrosine consistently improved cognitive performance under stress (cold exposure, sleep deprivation, high cognitive load), with minimal effect in non-stressed conditions. Preliminary, RCTs exist in non-tier-1 journals but are small or short-duration. No Cochrane review, EMA monograph or EFSA-authorised claim covers the indication. Acute, situation-specific use is the well-defined niche.
Preliminary, RCTs exist in non-tier-1 journals but are small or short-duration. No Cochrane review, EMA monograph or EFSA-authorised claim covers the indication.
- Mahoney et al., Physiol Behav 2007, tyrosine supplementation mitigates working memory decrements during cold exposure (RCT)
- Magill et al., Mil Psychol 2003, effects of tyrosine, phentermine, caffeine D-amphetamine, and placebo on cognitive and motor performance deficits during sleep deprivation
- Jongkees et al., J Psychiatr Res 2015, effect of tyrosine supplementation on clinical and healthy populations under stress or cognitive demands: review
Where to get it
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