What is tyrosine?
L-tyrosine is a non-essential amino acid synthesised in the body from phenylalanine. It is a precursor to several catecholamines — dopamine, adrenaline (epinephrine), and noradrenaline (norepinephrine) — as well as thyroid hormones. It is found in protein-rich foods including chicken, turkey, fish, dairy, and eggs.
How it works
Tyrosine is converted to L-DOPA, which is then converted to dopamine. Dopamine can subsequently be converted to noradrenaline and adrenaline. Under conditions of stress, sleep deprivation, or intense exercise, catecholamine synthesis increases and tyrosine availability can become rate-limiting. Supplementation replenishes this substrate pool, supporting sustained neurotransmitter production and cognitive function.
What the research says
- 100–150mg per kg bodyweight significantly improved cognitive performance under stress (cold exposure, sleep deprivation) in military research
- Reduced performance decrements from sleep deprivation and multitasking demands
- Effects are most pronounced under conditions that deplete catecholamines — stress, fatigue, extreme cold or heat
- Minimal effect on cognitive performance in rested, non-stressed individuals
Effective dose
500–2000mg taken 30–60 minutes before exercise or cognitively demanding tasks. N-acetyl L-tyrosine (NALT) is more water-soluble and commonly used in pre-workouts, though evidence that it converts more efficiently to L-tyrosine in the body is limited. Effects are most notable during fatiguing or high-stress training sessions.
What to check on the label
Many pre-workouts list tyrosine at 100–250mg — well below the effective dose range. Confirm at least 500mg per serve. Products using NALT should note that gram-for-gram it provides less actual tyrosine than L-tyrosine due to the acetyl group by weight.
Safety
Safe at recommended doses for healthy adults. May interact with MAO inhibitors and thyroid medications. Those with phenylketonuria (PKU) should avoid tyrosine supplementation. Avoid combining with stimulant medications without medical advice.