L-Tyrosine

Supplements · Amino Acids · Supplement, Typed Supps

A building block your brain uses for dopamine — helpful mainly when you’re under real stress, not as an everyday focus booster.

Stage by stage

Intake (Capsule or powder): Absorbed efficiently in the small intestine.
Small intestine (Efficient absorption): Absorbed alongside standard digestion.
Bloodstream (Crosses into the brain): Crosses into the brain after absorption.
Dopamine & adrenaline (Cognitive performance under stress): Used to build dopamine and adrenaline, most consistently studied for maintaining cognitive performance during acute physical or mental stress.

What the evidence supports

Preserving mental performance during acute stress such as cold, sleep loss, or heavy cognitive load — limited evidence. Small trials in demanding conditions show it can protect working memory and decision-making, but studies are small and short and the effect appears only when the brain's catecholamines are being depleted.
Improving cognition or mood in rested, unstressed people — insufficient evidence. The benefit is depletion-dependent and studies find no effect at baseline, so as an everyday nootropic it has not shown value.
Enhancing physical exercise performance — insufficient evidence. Trials are mixed and mostly small, with no consistent performance effect.

Typical dose

Study doses are large, around 100-150 mg/kg (often several grams) taken 30-60 minutes before the stressor; consumer products more commonly supply 500-1500 mg daily

Upper limit: No established upper limit; doses above roughly 12 g per day are not recommended

Timing

30–60 minutes before a stressful task, in most studied protocols.

Time to effect

~1 hr: For circulating levels to rise before a stressful task.

Medication interactions

MAOI antidepressants (including linezolid, selegiline): Can provoke a dangerous rise in blood pressure (hypertensive crisis). (high)
Levodopa: Competes with levodopa for the same absorption transporter, potentially reducing the drug's effect if taken together. (moderate)
Thyroid hormone medication: As a thyroid-hormone precursor it may add to thyroid hormone levels. (moderate)

Common myth

“Tyrosine boosts focus in everyday, low-stress situations.” In reality: Its clearest studied benefit is maintaining performance specifically under acute stress — evidence for everyday, non-stressed focus is much thinner.