amino acid · for lack of focus
L-Tyrosine
The raw material for dopamine. Under stress you burn through it, and topping up keeps focus from sliding.
Say that in clinical terms
L-tyrosine is the direct precursor to dopamine and norepinephrine via tyrosine hydroxylase. Under stressful conditions, catecholamine turnover increases and tyrosine supplementation prevents depletion, maintaining focused attention.
How strong is the research?
3 papers read, 3 supporting.
Who was studied: Military cadets during a week of combat training — extreme stress, no sleep, not enough food.
How much to take
daily on empty stomach
500–1000 mg
Take 30-60 minutes before meals. Most effective under conditions of stress, sleep deprivation, or high cognitive demand.
Before you take it
- No established NIH/IOM Tolerable Upper Intake Level (UL) for supplemental L-tyrosine; research doses up to 150 mg/kg/day (approximately 10 g/day for a 70 kg adult) have been administered in studies of up to 3 months without reported serious adverse effects.
- Contraindicated with monoamine oxidase inhibitors (MAOIs: phenelzine, tranylcypromine, selegiline, rasagiline) — L-tyrosine raises catecholamine precursor availability; MAOIs block catecholamine breakdown; combination risks hypertensive crisis.
- May compete with levodopa (L-DOPA) at the large neutral amino acid transporter (LAT1), potentially reducing L-DOPA efficacy in Parkinson's disease patients; separate doses by at least 2 hours.
- Caution in thyroid disease: tyrosine is a structural backbone of thyroid hormones T3 and T4; supplementation may alter thyroid hormone metabolism in patients with hyperthyroidism, Graves' disease, or those on thyroid medications (levothyroxine, liothyronine); monitor thyroid function.
- Pregnancy and lactation: no adequate safety data; avoid unless directed by a healthcare provider.
- Antibiotic timing: take at least 2 hours before or 4–6 hours after tetracycline or quinolone antibiotics.
- Melanoma: theoretical concern based on mechanistic reasoning (tyrosine is a precursor to melanin); high-dose supplementation should be used with caution in patients with active melanoma or high melanoma risk — not established by clinical trial data.
When to take it
Best taken: morning
What we make of it
It helps under extreme stress. That is the finding, and it is narrower than it sounds.
The detail
The systematic review examined the whole body of tyrosine research and concluded the benefit appears specifically under demanding conditions — stress, cold, sleep loss — rather than as a general aid to concentration.