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L-Tyrosine
L-tyrosine is one of the few nootropics with a real evidence base, but the evidence is narrow and the marketing usually misrepresents it.
- Evidence
- Mixed Evidence
- Category
- Cognitive & Nootropics
- Best form
- Plain L-Tyrosine (free-form amino acid powder or capsule; the form used in nearly every positive RCT)
- Effective dose
- 100-150 mg/kg as a single dose before an acute stressor (≈7-10 g for a 70 kg adult)
- Lab tested
- 4 of 10 products
- Category
- Cognitive & Nootropics
- Best form
- Plain L-Tyrosine (free-form amino acid powder or capsule; the form used in nearly every positive RCT)
- Effective dose
- 100-150 mg/kg as a single dose before an acute stressor (≈7-10 g for a 70 kg adult)
- Lab tested
- 4 of 10 products
Key takeaways
- →Strongest evidence is single pre-stressor doses of 100-150 mg/kg (7-10 g for a 70 kg adult) before cold, sleep loss, or demanding military training. That is 7-20x what a typical 500 mg consumer capsule delivers.
- →Plain L-tyrosine is the form used in nearly every positive RCT. NALT is more soluble but human PK data show poor conversion to free tyrosine; the marketing premium is not supported.
- →Not a depression, anxiety, or ADHD treatment. The signal lives in acute catecholamine-depleting stress, not chronic mood disorders.
- →For everyday focus on a normal workday, evidence at 500-1000 mg is thin. The honest framing is: it might help if you are actually catecholamine-depleted; if you slept well and feel fine, expect placebo.
What Is L-Tyrosine?
L-tyrosine is one of the few nootropics with a real evidence base, but the evidence is narrow and the marketing usually misrepresents it. The signal lives in one specific scenario: take a large single dose before an acute stressor that depletes catecholamines, and you can preserve working memory and reaction time that would otherwise degrade. The classic trials are Banderet & Lieberman 1989 (100 mg/kg before 4.5 hours of cold plus simulated altitude in military subjects), Neri 1995 (150 mg/kg during one night of total sleep deprivation in naval aviators), Mahoney 2007 (150 mg/kg before cold-water immersion), and Deijen 1999 (2 g/day during a week of demanding combat training in Dutch cadets). All four show preserved cognitive performance versus placebo when the stressor is harsh enough to actually deplete the catecholamine system.
The trial doses are the editorial story. Those studies used 100-150 mg/kg as a single pre-stressor dose, which is roughly 7-10 g for a 70 kg adult. Consumer capsules are typically 500-1000 mg. That is a 7-20x gap between what the bottle delivers and what the positive RCTs actually tested. A 500 mg morning capsule before a normal workday is not the Banderet protocol, and there is no reason to assume it produces the same effect.
The Leiden series under Lorenza Colzato extended the picture to non-stressor cognition in healthy adults: Steenbergen & Colzato 2015 reported reduced task-switching costs (cognitive flexibility) at 2 g, and the broader Jongkees, Hommel, Kühn & Colzato 2015 review concluded tyrosine "effectively enhances cognitive performance, particularly in short-term stressful and/or cognitively demanding situations" and "only when neurotransmitter function is intact." The signal in unstressed healthy adults is smaller than the military-stressor signal and inconsistent across tasks.
Where the evidence did not land: depression and ADHD. Small open-label trials in the 1980s explored tyrosine as a precursor-loading strategy for catecholamine-dependent psychiatric conditions, and the results were mostly negative or did not replicate. Tyrosine is not a treatment for depression, anxiety, or ADHD — the FDA structure/function framing here is cognitive support under acute load, nothing more.
On N-Acetyl-L-Tyrosine: NALT is heavily marketed as more bioavailable than plain L-tyrosine because it is more water-soluble, but human pharmacokinetic data show NALT is poorly deacetylated back to free tyrosine in vivo, and a large fraction of an oral NALT dose is excreted unchanged in urine. The branded premium is not supported by absorption data. If you want the form used in the published trials, plain L-tyrosine is the safer pick.
Practical read: if you specifically face an acute cognitive stressor (overnight on-call, cold exposure, a demanding exam after a bad night of sleep) a single 5-10 g pre-stressor dose of plain L-tyrosine is the closest you can get to the Banderet / Mahoney protocol. For everyday focus on a normal workday, the evidence is thin and 500 mg from a capsule is more placebo than pharmacology.
Does It Work? The Evidence
How A-F grades workPreserves cognitive performance during combined cold and hypoxia stress
Banderet & Lieberman 1989 (n=23 military subjects, 100 mg/kg before 4.5h cold + simulated altitude): tyrosine significantly reduced stress symptoms, mood disturbance, and performance impairments in subjects who responded to the stressor
Preserves cognitive performance during sleep deprivation
Neri et al. 1995 (n=20 naval aviators, 150 mg/kg during one night of total sleep deprivation): tyrosine significantly attenuated psychomotor performance decline for roughly 3 hours post-dose vs placebo
Preserves working memory during cold-water exposure
Mahoney et al. 2007 (n=19, 150 mg/kg before cold-water immersion): tyrosine alleviated cold-induced working memory decrements and improved match-to-sample performance vs placebo
Preserves cognitive performance during demanding military training
Deijen et al. 1999 (n=21 Dutch military cadets, 2 g/day x 5 days during combat training course): tyrosine group performed significantly better on memory and tracking tasks and showed lower diastolic blood pressure than carbohydrate-control group
Improves cognitive flexibility (task-switching) in unstressed healthy adults
Steenbergen, Sellaro, Hommel & Colzato 2015 (n=22 healthy adults, 2 g single dose, task-switching paradigm): tyrosine reduced switching costs vs placebo; effect specific to proactive cognitive control
Enhances cognitive performance in short-term stressful or demanding contexts (overall)
Jongkees, Hommel, Kühn & Colzato 2015 narrative review of ~15 studies: tyrosine improves cognition under stress or high cognitive load but does not enhance baseline performance in unstressed, well-rested healthy adults
Treats depression, ADHD, or chronic mood disorders
Small open-label and underpowered 1980s trials in depression and adult ADHD; results inconsistent and largely negative, with no replicated well-powered RCT supporting therapeutic benefit
N-Acetyl-L-Tyrosine (NALT) is more bioavailable than plain L-tyrosine
Pharmacokinetic studies show NALT is poorly deacetylated back to free tyrosine in humans and a substantial fraction is excreted unchanged in urine; marketed bioavailability advantage is not supported by absorption data
| Grade | Claimed Benefit | Key Studies | Our Verdict |
|---|---|---|---|
| B | Preserves cognitive performance during combined cold and hypoxia stress | Banderet & Lieberman 1989 (n=23 military subjects, 100 mg/kg before 4.5h cold + simulated altitude): tyrosine significantly reduced stress symptoms, mood disturbance, and performance impairments in subjects who responded to the stressor | Supported |
| B | Preserves cognitive performance during sleep deprivation | Neri et al. 1995 (n=20 naval aviators, 150 mg/kg during one night of total sleep deprivation): tyrosine significantly attenuated psychomotor performance decline for roughly 3 hours post-dose vs placebo | Supported |
| B | Preserves working memory during cold-water exposure | Mahoney et al. 2007 (n=19, 150 mg/kg before cold-water immersion): tyrosine alleviated cold-induced working memory decrements and improved match-to-sample performance vs placebo | Supported |
| B | Preserves cognitive performance during demanding military training | Deijen et al. 1999 (n=21 Dutch military cadets, 2 g/day x 5 days during combat training course): tyrosine group performed significantly better on memory and tracking tasks and showed lower diastolic blood pressure than carbohydrate-control group | Supported |
| C | Improves cognitive flexibility (task-switching) in unstressed healthy adults | Steenbergen, Sellaro, Hommel & Colzato 2015 (n=22 healthy adults, 2 g single dose, task-switching paradigm): tyrosine reduced switching costs vs placebo; effect specific to proactive cognitive control | Early Signal |
| B | Enhances cognitive performance in short-term stressful or demanding contexts (overall) | Jongkees, Hommel, Kühn & Colzato 2015 narrative review of ~15 studies: tyrosine improves cognition under stress or high cognitive load but does not enhance baseline performance in unstressed, well-rested healthy adults | Early Signal |
| D | Treats depression, ADHD, or chronic mood disorders | Small open-label and underpowered 1980s trials in depression and adult ADHD; results inconsistent and largely negative, with no replicated well-powered RCT supporting therapeutic benefit | Not There Yet |
| D | N-Acetyl-L-Tyrosine (NALT) is more bioavailable than plain L-tyrosine | Pharmacokinetic studies show NALT is poorly deacetylated back to free tyrosine in humans and a substantial fraction is excreted unchanged in urine; marketed bioavailability advantage is not supported by absorption data | Not There Yet |
How to Choose: Forms, Doses & What Matters
Clinical dose: 100-150 mg/kg as a single dose before an acute stressor (≈7-10 g for a 70 kg adult); typical consumer dosing of 500-1000 mg sits well below trial doses
Best forms: Plain L-Tyrosine (free-form amino acid powder or capsule; the form used in nearly every positive RCT), N-Acetyl-L-Tyrosine / NALT (marketed as more bioavailable but pharmacokinetic data show poor conversion back to L-tyrosine in humans; convenient for solubility, not better absorbed)
For the acute stressor protocol, take a single dose of roughly 100-150 mg/kg (5-10 g for most adults) on an empty stomach 30-60 minutes before the stressor. The published trials dosed this way: one large pre-event dose, not a chronic daily regimen. Plain L-tyrosine powder is the cheapest and easiest way to hit this dose — capsules at 500-1000 mg per cap would require 7-20 capsules to match the trial dose, which is impractical and expensive. Take on an empty stomach: tyrosine competes with other large neutral amino acids (especially phenylalanine, leucine, valine, isoleucine) for the same transporter into the brain, so a high-protein meal blunts absorption into the CNS. For the lower-dose daily nootropic use, 500-2000 mg once in the morning on an empty stomach is the typical pattern, but understand this is below the dose where the RCTs read out positive.
Who Should Take L-Tyrosine?
Adults facing a specific, acute cognitive stressor where catecholamine depletion is plausible: an overnight on-call shift, a demanding cognitive task after a poor night of sleep, cold exposure, or high-stress training. The closest match to the published protocols is a single pre-stressor dose in the 5-10 g range (matching 100-150 mg/kg in trial subjects). Lower 500-1000 mg doses are reasonable to experiment with as a stacked nootropic but should be understood as well below the dose where trial-level effects were observed.
Who Should Avoid It?
Not for everyone
Side Effects & Safety
Product Scores
10 products scored on dosing accuracy, third-party testing, cost per effective dose, and label transparency.
The Scorecard: 10 Products Compared
L-Tyrosine Powder, 500g
BulkSupplements
$34.96 ÷ 499 days at 1000mg/day (1 serving × 1000mg)
The pick if you want to actually replicate the Banderet/Mahoney pre-stressor protocol at 5-10 g; capsules become impractical and expensive at that dose
Prices checked 2026-05-15. Cost shown is per clinically effective daily dose, not per pill.
L-Tyrosine 500mg, 120 Capsules
NOW Foods$12.99 ÷ 118 days at 500mg/day (1 serving × 500mg)
The workhorse pick for everyday tyrosine use at consumer doses; if you want to hit trial-level 5-10 g doses, switch to a plain powder rather than scaling capsules
Prices checked 2026-05-15. Cost shown is per clinically effective daily dose, not per pill.
L-Tyrosine 500mg, 180 Capsules
Double Wood Supplements$21.95 ÷ 183 days at 500mg/day (1 serving × 500mg)
Strong everyday pick that pairs NOW-level pricing with a brand-level third-party testing program
Prices checked 2026-05-15. Cost shown is per clinically effective daily dose, not per pill.
L-Tyrosine 500mg, 100 Capsules
Jarrow Formulas$15.95 ÷ 100 days at 500mg/day (1 serving × 500mg)
Reasonable swap for NOW if you already buy Jarrow; quality is comparable and the active is identical
Prices checked 2026-05-15. Cost shown is per clinically effective daily dose, not per pill.
L-Tyrosine 500mg, 120 Capsules
Doctor's Best$15.99 ÷ 123 days at 500mg/day (1 serving × 500mg)
Clean budget pick at the consumer-standard dose; like all 500mg capsules, do not expect to replicate Banderet-level effects from one cap
Prices checked 2026-05-15. Cost shown is per clinically effective daily dose, not per pill.
L-Tyrosine 500mg, 240 Capsules
Nutricost$21.95 ÷ 244 days at 500mg/day (1 serving × 500mg)
Workhorse cheapest-per-cap option from a reputable brand; functionally indistinguishable from NOW or Jarrow on the active ingredient
Prices checked 2026-05-15. Cost shown is per clinically effective daily dose, not per pill.
L-Tyrosine, 90 Capsules
Thorne$27.00 ÷ 90 days at 500mg/day (1 serving × 500mg)
Pick for buyers who specifically trust Thorne's QA over generic GMP; for athletes subject to drug testing, verify the NSF status on your specific lot before relying on this SKU
Prices checked 2026-05-15. Cost shown is per clinically effective daily dose, not per pill.
L-Tyrosine 500mg, 100 Vegetable Capsules
Solgar$21.99 ÷ 100 days at 500mg/day (1 serving × 500mg)
Reasonable mainstream-tier pick if Solgar is your trusted brand; functionally identical active to the cheaper options
Prices checked 2026-05-15. Cost shown is per clinically effective daily dose, not per pill.
L-Tyrosine 500mg, 100 Tablets
Source Naturals
$19.50 ÷ 98 days at 500mg/day (1 serving × 500mg)
Standard mainstream pick; tablet form is the main differentiator and not a strict advantage over a capsule
Prices checked 2026-05-15. Cost shown is per clinically effective daily dose, not per pill.
N-Acetyl L-Tyrosine 300mg, 60 Capsules
Nootropics Depot$15.99 ÷ 59 days at 300mg/day (1 serving × 300mg)
Excellent QA on a form whose marketing claim does not hold up in human PK data; if you want the form used in the trials, buy plain L-tyrosine instead
Prices checked 2026-05-15. Cost shown is per clinically effective daily dose, not per pill.
Full Comparison
| Category | L-Tyrosine Powder, 500g BulkSupplements | L-Tyrosine 500mg, 120 Capsules NOW Foods | L-Tyrosine 500mg, 180 Capsules Double Wood Supplements | L-Tyrosine 500mg, 100 Capsules Jarrow Formulas | L-Tyrosine 500mg, 120 Capsules Doctor's Best | L-Tyrosine 500mg, 240 Capsules Nutricost | L-Tyrosine, 90 Capsules Thorne | L-Tyrosine 500mg, 100 Vegetable Capsules Solgar | L-Tyrosine 500mg, 100 Tablets Source Naturals | N-Acetyl L-Tyrosine 300mg, 60 Capsules Nootropics Depot |
|---|---|---|---|---|---|---|---|---|---|---|
| Brand Score | 88/100Winner | 84/100 | 82/100 | 82/100 | 80/100 | 79/100 | 78/100 | 76/100 | 74/100 | 68/100 |
| Dosing & Form | 25/25Winner | 22/25 | 22/25 | 22/25 | 22/25 | 22/25 | 22/25 | 22/25 | 20/25 | 14/25 |
| Purity | 19/25 | 16/25 | 19/25 | 16/25 | 13/25 | 13/25 | 23/25Winner | 13/25 | 13/25 | 22/25 |
| Value | 25/25Winner | 23/25 | 22/25 | 21/25 | 22/25 | 25/25 | 10/25 | 18/25 | 18/25 | 13/25 |
| Transparency | 19/25 | 23/25Winner | 19/25 | 23/25 | 23/25 | 19/25 | 23/25 | 23/25 | 23/25 | 19/25 |
| Cost/Day | $0.07Winner | $0.11 | $0.12 | $0.16 | $0.13 | $0.09 | $0.30 | $0.22 | $0.20 | $0.27 |
| Dose/Serving | 1000mg | 500mg | 500mg | 500mg | 500mg | 500mg | 500mg | 500mg | 500mg | 300mg |
| Form | L-Tyrosine (free-form powder) | L-Tyrosine (capsule) | L-Tyrosine (capsule) | L-Tyrosine (vegetarian capsule) | L-Tyrosine (vegan capsule) | L-Tyrosine (vegetarian capsule) | L-Tyrosine (capsule) | L-Tyrosine (vegetable capsule) | L-Tyrosine (tablet) | N-Acetyl L-Tyrosine (capsule) |
| Third-Party Tested | ✓ Yes | No | ✓ Yes | No | No | No | ✓ Yes | No | No | ✓ Yes |
| Proprietary Blend | No | No | No | No | No | No | No | No | No | No |
Frequently Asked Questions
What is the difference between L-tyrosine and N-Acetyl-L-Tyrosine (NALT)?
NALT is L-tyrosine with an acetyl group attached, which makes it more water-soluble — useful for liquid formulations and the reason it shows up in nootropic stacks. The marketing claim is that NALT is more bioavailable than plain L-tyrosine, but human pharmacokinetic data tell a different story: NALT is poorly converted back to free tyrosine in vivo, and a large fraction of an oral NALT dose is excreted unchanged in urine. Plain L-tyrosine is the form used in essentially every positive RCT (Banderet, Neri, Mahoney, Deijen, Colzato), and it is cheaper. If you want the form with the evidence behind it, buy plain L-tyrosine.
Why is the trial dose so much higher than what is on the bottle?
The published RCTs used 100-150 mg/kg as a single pre-stressor dose, which is roughly 7-10 g for a 70 kg adult. Standard consumer capsules are 500-1000 mg. That is a 7-20x gap. The supplement industry settled on 500-1000 mg per capsule because that is a convenient capsule size and it sounds like a real dose, not because that dose was tested in the trials. If you want to replicate the Banderet or Mahoney protocol, you need to dose much higher than a single capsule — which is easier with plain L-tyrosine powder (5-10 g is a teaspoon or two).
Will L-tyrosine help me focus on a normal day?
Probably not much. The published evidence is strongest when subjects are catecholamine-depleted: sleep-deprived, cold-stressed, mid-combat-training. The Jongkees 2015 review made this explicit — tyrosine works when neurotransmitter function is compromised, not when you are well-rested and feel fine. On a normal workday at a normal dose, expect a placebo-level effect. The honest use case is the harder stressor: pulling an all-nighter, an overnight clinical shift, a demanding cognitive test after a bad night of sleep.
Is L-tyrosine safe to take every day?
At typical supplemental doses (500-2000 mg/day), short-term daily use looks safe in the trials that have been run. Deijen 1999 dosed cadets 2 g/day for 5 days without issues. There is no long-term safety database at high chronic doses, and theoretical concerns exist for thyroid function and levodopa interaction. The acute-stressor protocol (5-10 g as a single pre-event dose) is not meant to be a daily regimen — it is intermittent use before specific stressors. The hard contraindications are MAOIs, hyperthyroidism, and active levodopa therapy.
Does L-tyrosine treat depression or ADHD?
No. The catecholamine-precursor hypothesis got tested in small trials in the 1980s for depression and adult ADHD, and the results were mostly negative or did not replicate. Tyrosine is not a substitute for an SSRI, SNRI, or stimulant medication, and the supplement-marketing framing of 'natural dopamine support for mood' is not supported by the trial record. If you have a clinical mood or attention disorder, this is a conversation for a physician, not a supplement bottle.
Can I take L-tyrosine with coffee?
Yes, no documented interaction. Caffeine and tyrosine work through different mechanisms — caffeine blocks adenosine receptors, tyrosine supplies precursor for catecholamine synthesis — and stacking them is common in nootropic practice. The one thing to watch is that taking tyrosine on a full stomach blunts its CNS uptake (it competes with other amino acids for the same transporter), so black coffee plus tyrosine on an empty stomach is the cleaner protocol than coffee with a high-protein breakfast.
How fast does L-tyrosine work?
Plasma tyrosine peaks roughly 1-2 hours after an oral dose, and the trial protocols dosed 30-60 minutes before the stressor began. The cognitive effects in the positive trials emerged within 1-3 hours of dosing. This is an acute-effect supplement at the trial dose — there is no loading period the way there is for creatine. If you are not feeling anything at 90 minutes post-dose, dosing longer is unlikely to change that.
Sources
- Banderet LE, Lieberman HR. Treatment with tyrosine, a neurotransmitter precursor, reduces environmental stress in humans. Brain Res Bull. 1989;22(4):759-762.
- Neri DF, Wiegmann D, Stanny RR, Shappell SA, McCardie A, McKay DL. The effects of tyrosine on cognitive performance during extended wakefulness. Aviat Space Environ Med. 1995;66(4):313-319.
- Mahoney CR, Castellani J, Kramer FM, Young A, Lieberman HR. Tyrosine supplementation mitigates working memory decrements during cold exposure. Physiol Behav. 2007;92(4):575-582.
- Deijen JB, Wientjes CJ, Vullinghs HF, Cloin PA, Langefeld JJ. Tyrosine improves cognitive performance and reduces blood pressure in cadets after one week of a combat training course. Brain Res Bull. 1999;48(2):203-209.
- Steenbergen L, Sellaro R, Hommel B, Colzato LS. Tyrosine promotes cognitive flexibility: evidence from proactive vs. reactive control during task switching performance. Neuropsychologia. 2015;69:50-55.
- Jongkees BJ, Hommel B, Kühn S, Colzato LS. Effect of tyrosine supplementation on clinical and healthy populations under stress or cognitive demands--A review. J Psychiatr Res. 2015;70:50-57.
FDA Disclaimer: These statements have not been evaluated by the Food and Drug Administration. The products discussed on this page are not intended to diagnose, treat, cure, or prevent any disease. Always consult with a qualified healthcare professional before starting any supplement regimen.