L-Tyrosine
Research Reliability -
An amino acid precursor to dopamine, norepinephrine, and thyroid hormones that supports focus, mood, and stress response.
Appetite
Mood
Sleep
L-Tyrosine
Description
L-Tyrosine is a non-essential amino acid that serves as the direct precursor to the catecholamine neurotransmitters dopamine, epinephrine, and norepinephrine, as well as thyroid hormones T3 and T4. Its cognitive benefits are most pronounced under conditions of stress, sleep deprivation, or extreme physical exertion, where catecholamine depletion can impair motivation, mental performance, and working memory. Research in military and cognitively demanding contexts shows tyrosine supplementation can sustain performance under these challenging conditions. It is commonly taken before high-stress events or demanding cognitive work.
Effects
First dose
sharper focus under stress within an hour
Same day
most useful before demanding or sleep-deprived tasks
Situational
works best when you are depleted
How it Feels
You feel this most when stressed, tired, or under cognitive load: a steadier, more resilient focus within the hour. On a well-rested day the effect is muted, since it tops up depleted dopamine precursors rather than boosting a full tank. Take on an empty stomach.
Usage
Entry Dose
250mg
Standard Dose
500–1000mg
Max Dose
2000mg
Onset
30–60 min (acute cognitive)
Combinations
Pairs well with
Synergistic
Vitamin B6 + folate — cofactors for tyrosine hydroxylase, the dopamine synthesis enzyme
Caffeine — tyrosine replenishes catecholamines that caffeine depletes under stress
Ashwagandha — tyrosine provides the substrate; ashwagandha reduces cortisol competing for it
Avoid combining
Contraindicated
MAOIs — tyrosine is metabolized by MAO; combination risks dangerous hypertensive crisis
Thyroid medications — tyrosine is a precursor to thyroid hormones; may affect dose requirements
Biomarkers to Track
Subjective
(Daily)
Mental focus under stress (1–10)
Motivation and drive score
Mood and energy levels
Objective
(Quarterly)
Salivary cortisol (AM level)
Thyroid TSH and free T3/T4
Plasma catecholamines (specialty)
Generally safe. It interacts with thyroid medication and MAOI antidepressants.
People on thyroid meds or MAOIs, and those with hyperthyroidism.
Taking it with food (it competes with protein) and expecting an effect when well-rested rather than stressed.
Preliminary (limited / small human data)
Benefit appears concentrated in situations of acute stress, cold exposure, or sleep deprivation, not general everyday cognitive enhancement.
Jongkees BJ et al. (2015). Journal of Psychiatric Research. Review (tyrosine and cognitive performance under stress). PMID: 26424423.