L-tyrosine
An amino acid in protein foods, also sold as N-acetyl-L-tyrosine (NALT)
An amino acid found in protein foods such as cheese, meat, fish and beans, and studied mostly for thinking and memory under stress, such as cold, heat or a night without sleep. Here is every study in people we could find, sorted from each study's summary.
- Found in: cheese, meat, fish and beans
- Often dosed by body weight
- Often a single dose
From every paper to the studies that matter
Most papers on tyrosine are about its role in the body, not about taking it. The studies in people are mostly of three kinds. Many give one large dose before a hard task. Many older ones are tyrosine load tests, which measured how the body clears a big dose, often in thyroid or liver disease. Smaller groups look at inherited conditions such as PKU, and only a few last a week or more.
-
16,457 papers mention tyrosine. Every record in PubMed, all years
-
360 are about people. The rest: 7,496 lab and animal studies, 482 reviews, 8,119 on chemistry, farming and more
-
140 give L-tyrosine or NALT on its own. 42 more test it inside a blend, often with other amino acids
-
61 are randomised against a placebo. The strongest kind of study
Bar lengths use a square-root scale so the small numbers stay visible.
How much research there is
- 140 studies giving L-tyrosine to people
- 61 of them randomised against a placebo
- 1,774 people taking part, where studies say
- 38 systematic reviews pooling the trials
Studies in people, by year published
L-tyrosine or NALT on its own.
What the studies looked at
Each study can measure several things. Choose a topic to see its studies in the list below.
Studies in people with a diagnosed condition are counted here and listed with their population. We describe what they measured, not what they might treat. Most studies also report safety; see below.
What was tested, and how much
L-tyrosine is a single compound, so milligrams compare directly. But most studies gave one dose sized to body weight, often 100 to 150 mg per kg (about 7 to 10 g for a 70 kg adult), and only studies with a set daily dose appear on this chart. Supplements also sell it as N-acetyl-L-tyrosine (NALT). The few studies of NALT in people gave it by drip, and much of it passed out unchanged in urine.
Daily amount, one dot per study
Studies per extract
Named extracts are the maker's brand. "Not named" means the study didn't say.
All studies in people
Filter the list, then open a study on PubMed. Each row comes from the study's published summary, and older studies with no summary online were sorted from the title.
| Study | Who took part | People | Extract and daily dose | Length |
|---|---|---|---|---|
| Lin 2026Single-arm or open-label | Healthy adults | 48 | Not named | – |
| Matsumoto 2026Crossover, placebo | Healthy adult men | 30 | Not named, 4,000 mg | 4 weeks |
| Bilgin 2026Crossover, placebo | Professional male football players | 24 | Not named | – |
| Solon-Júnior 2026Crossover, placebo | Mentally fatigued recreational cyclists | 12 | Not named | – |
| Averdunk 2026Single-arm or open-label | Children with YARS1 deficiency | 9 | Not named | – |
| Donnan 2025Crossover, placebo | Trained male soccer players | 8 | Not named | – |
| McAllister 2024RCT, placebo | Healthy young adults, mental stress challenge | 80 | Not named, 2,000 mg | – |
| Hart 2024RCT, placebo | Adolescents with anorexia nervosa | 7 | Not named, 5 mg | 12 weeks |
| Mathar 2022Crossover, placebo | Healthy young men | 28 | Not named, 2,000 mg | – |
| Lim 2021RCT, placebo | Healthy volunteers | 48 | Not named | – |
| Hart 2021Pharmacokinetic | Adolescents with anorexia nervosa and healthy peers | 4 | Not named | 12 weeks |
| Robson 2020RCT, placebo | Healthy volunteers under cognitive load | 70 | Not named, 2,000 mg | – |
| Jongkees 2020Crossover, placebo | Healthy young adults | 45 | Not named, 2,000 mg | – |
| Ahrens 2020RCT, placebo | Healthy adult non-smokers | 38 | Not named, 2,000 mg | – |
| Lang 2020Crossover, placebo | Healthy young and older adults, cold exposure | 18 | Not named | – |
| Tumilty 2020Crossover, placebo | Recreationally trained men, warm environment | 8 | Not named | – |
| Froböse 2020Crossover, placebo | Healthy older adults aged 60-75 | – | Not named | – |
| Soranzo 2019RCT, placebo | Healthy adults | 46 | Not named | – |
| Dennison 2019Crossover, placebo | Healthy adults, tDCS and tyrosine | – | Not named | – |
| Stock 2018Crossover, placebo | Young healthy adults | 26 | Not named | – |
| Bloemendaal 2018Crossover, placebo | Healthy older adults aged 61-72 | 24 | Not named | – |
| van de Rest 2017RCT, active or other control | Healthy older and young adults | 34 | Not named | – |
| Lang 2017Crossover, placebo | Healthy young and older adults, cold exposure | 22 | Not named | – |
| Israely 2017Crossover, placebo | Hospitalised women with chronic anorexia nervosa | 19 | Not named | 3 weeks |
| Coull 2016RCT, placebo | Healthy adults in heat stress | 21 | Not named | – |
| Colzato 2016RCT, placebo | Healthy adults by DRD2 genotype | – | Not named | – |
| Lieberman 2015RCT, placebo | Military personnel in survival school stress | 78 | Not named | – |
| Steenbergen 2015RCT, placebo | Healthy adults | 22 | Not named | – |
| Coull 2015Crossover, placebo | Male soccer players | 8 | Not named | – |
| Colzato 2015RCT, placebo | Healthy adults, creativity tasks | – | Not named | – |
| DiFrancisco-Donoghue 2014RCT, placebo | Parkinson disease patients on levodopa | 36 | Not named, 1,000 mg | 1 weeks |
| Dowlati 2014RCT, placebo | Healthy breastfeeding women | 24 | Not named, 10,000 mg | – |
| Tumilty 2014Crossover, placebo | Endurance-trained men, exercise in heat | 7 | Not named | – |
| Colzato 2014Crossover, placebo | Healthy adults | – | Not named | – |
| Jongkees 2014Other | Healthy adults | – | Not named | – |
| Kishore 2013Crossover, placebo | Healthy young men, heat exposure | 10 | Not named, 6,500 mg | – |
| Colzato 2013Other | Healthy adults | – | Not named | – |
| Watson 2012Crossover, placebo | Healthy young men, exercise in heat | 8 | Not named | – |
| Tumilty 2011Crossover, placebo | Healthy trained men, heat exercise | 8 | Not named | – |
| Lang 2010Other | Young and older healthy adults | 20 | Not named | – |
| Badaloo 2010Other | Children recovering from severe undernutrition | 13 | Not named | – |
| Belza 2009Crossover, placebo | Healthy normal-weight men | 12 | Not named, 400 mg | – |
| Rafii 2008Other | Healthy adult men on controlled diet | 6 | Not named | – |
| Ryan 2008Single-arm or open-label | Patients with nemaline myopathy | 5 | Not named, 3,000 mg | – |
| Palinkas 2007RCT, placebo | Healthy adults living in Antarctica | 43 | Not named, 12,000 mg | 20 weeks |
| Mahoney 2007Crossover, placebo | Healthy volunteers in cold water | 19 | Not named | – |
| O'Brien 2007Crossover, placebo | Healthy subjects in cold water | 15 | Not named | – |
| Sutton 2005Crossover, placebo | Healthy men in load-carriage test | 20 | Not named | – |
| Waters 2003RCT, placebo | Healthy young men, sleep-deprived | 76 | Not named | – |
| Hoffer 2003Other | Adults on parenteral nutrition | 13 | N-acetyl-L-tyrosine | – |
| Magill 2003RCT, placebo | Healthy young men, sleep-deprived | – | Not named | – |
| Cui 2003Other | Youths exercising at 3700 m altitude | – | Not named | – |
| Chinevere 2002Crossover, placebo | Competitive male cyclists | 9 | Not named | – |
| Kalsner 2001Pharmacokinetic | People with phenylketonuria on diet | 10 | Not named | – |
| Roberts 2001Other | Healthy men | 6 | Not named | – |
| Thorpe 2000Other | Healthy men | – | Not named | – |
| Deijen 1999RCT, active or other control | Military cadets in combat training | 21 | Not named | – |
| Thomas 1999Crossover, placebo | Healthy men and women | 20 | Not named | – |
| Wiesel 1999Non-randomised controlled | Patients with schizophrenia and healthy controls | 10 | Not named | – |
| Smith 1998Crossover, placebo | People with phenylketonuria aged 6-28 | 21 | Not named | 4 weeks |
| Strüder 1998Crossover, placebo | Healthy trained male cyclists | 10 | Not named, 20,000 mg | – |
| Lines 1997Other | People with phenylketonuria | – | Not named | – |
| Galloway 1996Single-arm or open-label | Cocaine-dependent outpatients | 49 | Not named, 6,000 mg | 13 weeks |
| Winter 1996Single-arm or open-label | 2-year-old boy with narcolepsy | 1 | Not named | – |
| Pietz 1995Crossover, placebo | Adults with phenylketonuria | 24 | Not named | 4 weeks |
| Dollins 1995Crossover, placebo | Healthy adults, lower body negative pressure | 20 | Not named | – |
| Druml 1995Pharmacokinetic | Hepatic failure patients and healthy adults | 13 | N-acetyl-L-tyrosine | – |
| Neri 1995RCT, placebo | Healthy adults, one night without sleep | – | Not named | – |
| Deijen 1994Crossover, placebo | Healthy young adults under noise stress | 16 | Not named | – |
| Shurtleff 1994Crossover, placebo | Healthy men, cold exposure | 8 | Not named | – |
| Clayton 1994Crossover, placebo | Healthy male volunteers given ethanol | – | Not named | – |
| Deutsch 1994Crossover, placebo | Schizophrenia inpatients on molindone | – | Not named, 10,000 mg | 3 weeks |
| Christensen 1993Pharmacokinetic | Infants on pediatric amino acid solution | – | N-acetyl-L-tyrosine | – |
| Wässer 1992Crossover, placebo | Children with phenylketonuria | 8 | Not named | 13 weeks |
| Mazzocco 1992Other | School-aged children with phenylketonuria | – | Not named | – |
| Druml 1991Pharmacokinetic | Hemodialysis patients and healthy controls | 15 | N-acetyl-L-tyrosine | – |
| Gelenberg 1990RCT, placebo | Outpatients with major depression | 65 | Not named | 4 weeks |
| Magnusson 1989Other | Healthy volunteers | 11 | N-acetyl-L-tyrosine, 5,000 mg | – |
| Lemoine 1989Single-arm or open-label | Parkinson's disease patients | 10 | Not named | 156 weeks |
| Elwes 1989Crossover, placebo | People with narcolepsy and cataplexy | 10 | Not named, 9,000 mg | 4 weeks |
| Dissing 1989Single-arm or open-label | Parkinson's disease patients | 5 | Not named, 15,000 mg | 7 weeks |
| Carlson 1989Other | Normal subjects | – | Not named | – |
| Banderet 1989Crossover, placebo | Healthy volunteers exposed to cold and hypoxia | – | Not named | – |
| Mouret 1988Single-arm or open-label | Patients with dopamine-dependent depression | 12 | Not named, 3,200 mg | – |
| Mouret 1988Single-arm or open-label | Narcolepsy patients | 8 | Not named | 26 weeks |
| Al-Damluji 1988Crossover, placebo | Healthy men | 8 | Not named | – |
| Eisenberg 1988Single-arm or open-label | Children with ADHD | 7 | Not named | – |
| Lou 1987Non-randomised controlled | Phenylketonuria patients aged 15-24 | 14 | Not named | – |
| Reimherr 1987Single-arm or open-label | Adults with attention deficit disorder | 12 | Not named | 8 weeks |
| Kondo 1987Single-arm or open-label | Juvenile parkinsonism patients and relatives | – | Not named | – |
| Wernze 1986Non-randomised controlled | Cirrhosis patients and healthy controls | 28 | Not named, 14,000 mg | 0 weeks |
| Lieberman 1985Crossover, placebo | Healthy young men | 20 | Not named | – |
| Cuche 1985Other | Healthy men | 15 | Not named | – |
| Sole 1985Crossover, placebo | Adults with mild essential hypertension | 13 | Not named, 7,500 mg | 2 weeks |
| Kvittingen 1985Other | Two healthy adults with low enzyme activity | 2 | Not named | – |
| Ni 1985Other | Adult men | – | Not named | – |
| Raw 1984Non-randomised controlled | Congenital pain insensitivity patients and controls | – | Not named | – |
| Lieberman 1984RCT, placebo | Unclear | – | Not named | – |
| Johnston 1983Non-randomised controlled | Normal-weight and obese women | 21 | Not named | 1 weeks |
| Ishizuka 1983Other | Healthy men | 7 | Not named | – |
| Benedict 1983RCT, active or other control | Healthy male volunteers | – | Not named, 7,500 mg | – |
| Yamaguchi 1983Non-randomised controlled | Parkinson's disease patients and healthy controls | – | Not named | – |
| Rasmussen 1983RCT, placebo | Healthy fasted men | – | Not named | – |
| Leathwood 1982Crossover, placebo | Healthy volunteers | 60 | Not named, 500 mg | – |
| Growdon 1982Single-arm or open-label | Parkinson's disease patients | 23 | Not named | – |
| Alonso 1982Non-randomised controlled | Human volunteers | – | Not named | – |
| Agharanya 1981Single-arm or open-label | Healthy volunteers | 11 | Not named | 0 weeks |
| Antener 1981Non-randomised controlled | Malnourished young mothers and healthy controls | – | Not named | – |
| Melamed 1980Single-arm or open-label | Healthy volunteers | 11 | Not named | 0 weeks |
| Gelenberg 1980Single-arm or open-label | Depressed patient (case report) | 1 | Not named | – |
| Hoskins 1980Other | Depression patients | – | Not named | – |
| Gelenberg 1980Other | Depression patients | – | Not named | – |
| Nordlinger 1979Non-randomised controlled | Cirrhotic patients and controls | 26 | Not named | – |
| Glaeser 1979Pharmacokinetic | Human volunteers | – | Not named | – |
| Zinsser 1973Other | Humans, oxalate excretion | – | Not named | – |
| Tarlow 1972Pharmacokinetic | Child with Hartnup variant and coeliac disease | 1 | Not named | – |
| Barrera 1971Other | Humans, taste threshold test | – | Not named | – |
| Williams 1971Other | Thyroid disease patients | – | Not named | – |
| Cavagnini 1970Other | Humans, plasma insulin | – | Not named | – |
| Calne 1970Other | Humans, sympathetic nerve function | – | Not named | – |
| Modignani 1970Other | Hyperthyroid patients | – | Not named | – |
| Braham 1969Non-randomised controlled | Parkinson's disease patients and controls | – | Not named | – |
| Fox 1968Other | Thyroid disease patients | – | Not named | – |
| Besser 1968Other | Thyroid disease patients | – | Not named | – |
| Lotti 1968Non-randomised controlled | Thyroid disease patients and normal subjects | – | Not named | – |
| Levine 1967Non-randomised controlled | Liver disease patients and normal subjects | – | Not named | – |
| Farran 1966Other | Thyrotoxicosis patients | – | Not named | – |
| Kalliomäki 1966Other | Rheumatoid arthritis patients | – | Not named | – |
| RIVLIN 1965Other | Thyrotoxicosis and myxedema patients | – | Not named | – |
| Tolbert 1963Other | Women on minimal tyrosine diet | – | Not named | – |
| VARTIAINEN 1962Non-randomised controlled | Patients with Addison's disease | – | Not named | – |
| HUANG 1961Pharmacokinetic | Human subjects | – | Not named | – |
| LEVERTON 1956Other | Young women | – | Not named | – |
| ROSE 1955Other | Adult volunteers | – | Not named | – |
| SPICKARD 1954Other | Allergic patients | – | Not named | – |
| CONNER 1954Other | Allergic patients | – | Not named | – |
| VARTIANINEN 1953Other | Human subjects | – | Not named | – |
| FERRERO 1950Other | Chronic polyarthritis patients | – | Not named | – |
| WOOLF 1950Other | Premature infants | – | Not named | – |
| CARRIE 1950Pharmacokinetic | Human subjects | – | Not named | – |
What's known about safety
-
In trials
In a 4-week trial of up to 4 g a day in 30 healthy men, side effects were no more common than with placebo. Nearly every other study gave a single dose, so long-term use is little studied.
Matsumoto 2026, 4-week trial at 1 to 4 g a day; Hase 2015, review of 15 studies, all but one a single dose
-
In the UK
Amino acids such as L-tyrosine can be used in food supplements. We found no official UK or EU upper limit. Norway's food safety committee judged 1,250 to 2,000 mg a day from supplements may carry a risk, based on a rat study, as long-term studies in people were lacking.
FSA food supplements guidance; EU Novel Food Status Catalogue, no entry for tyrosine or NALT; VKM 2016, Norway; searches of FSA and EFSA, Oct 2026
-
Check first
It isn't known whether it's safe in pregnancy or breastfeeding, it hasn't been studied for safety in healthy children, and how it mixes with medicines isn't well studied. Speak to a pharmacist or doctor first if any of these applies to you.
VKM 2016, Norway, no data in pregnancy, breastfeeding or children; no UK guidance found, Oct 2026
Where these studies come from
We list every published study of L-tyrosine and NALT in people. This first version is built from each study's summary; full-paper checks come next.
-
We search
PubMed, the world's main library of medical research, for every paper on L-theanine.
-
We keep studies in people
Lab and animal work is counted but left out of the list, because it doesn't tell you what happens in people.
-
We note the basics
Who took part, how many, how much and for how long, from each study's published summary. A second check corrects what the first read gets wrong.
-
We read them in full
Results appear once we've read the whole paper and checked every number. The date at the top shows when this entry was last updated.
Download the study list
Every study in people as a spreadsheet, 140 rows, free to reuse with a link back.
Versions
Each update to the data gets a new version number, so you can tell what changed and when.
See every version
1.0 · 19 Oct 2026. First release. Every published study giving L-tyrosine on its own to people is listed from its summary. None is read in full yet.
Related
- Ingredient AtlasEvery ingredient in the Atlas
- Ingredient AtlasAshwagandha research