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L-Tyrosine

L-Tyrosine is an amino acid that is used to produce noradrenaline and dopamine; it appears to reduce stress during exposure to acute stressors (which tend to deplete noradrenaline) and may help to prevent stress-induced memory and attention deficits.

Our evidence-based analysis on l-tyrosine features 68 unique references to scientific papers.

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Summary of L-Tyrosine

Primary information, health benefits, side effects, usage, and other important details

What is L-Tyrosine?

L-Tyrosine is an amino acid found in the diet that is metabolized to produce catecholamines such as dopamine and adrenaline. It is also used in the production of thyroid hormones. For these reasons, weight loss and preworkout supplements often include it.

What are L-Tyrosine's benefits?

When it comes to the topic of actually increasing dopamine and adrenaline outright, L-tyrosine does not seem to hold much promise. The synthesis of catecholamines is highly regulated in the body, so simply increasing the amount of L-tyrosine in your body does not necessarily increase catecholamine production.

However, some studies have noted that in stressful situations where noradrenaline exerts a protective effect, supplying L-tyrosine seems to provide a 'safety buffer' of building blocks that can prolong the anti-stress effect of catecholamines by delaying their depletion. This has been noted in situations of cold stress, psychological stress, and sleep deprivation in humans but at a relatively high dose of 150mg/kg. Improvements in memory and attention during stressful situations have been found, though the effect doesn't appear to be very big or reliable.

What are L-Tyrosine'side effects and drawbacks?

It's generally safe. It's one of the basic amino acid that makes up proteins in the human body, so while that doesn't mean that any amount is safe, it does suggest that the body knows how to handle it safely.

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How to Take

Medical Disclaimer

Recommended dosage, active amounts, other details

Anecdotally, L-Tyrosine tends to be taken in doses of 500-2000mg approximately 30-60 minutes before any acute stressor (this tends to be exercise)

Studies in humans showing most anti-stress promise for acute supplemental L-Tyrosine use a dosage range of 100-150mg/kg bodyweight which can be taken 60 minutes before exercise; this is a dosage range of 9-13.5g for a 200lb person and 7-10g for a 150lb person.

If using higher doses and finding digestive issues, this may be split into two doses separated by half an hour (30 and 60 minutes prior to acute stress).

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Human Effect Matrix

Unlocked for Examine members

The Human Effect Matrix summarizes human studies to tell you what effects L-Tyrosine has on your body, how much evidence there is, and how strong these effects are.

Full details are available to Examine members.
Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
Notes
grade-b Minor Very High See all 9 studies
Appears to preserve working memory during acute stressors. Acute stressors include temperature changes, psychological, and sleep deprivation. It's not clear if it has inherent memory-improving effects, as most research doesn't examine this, and what research we do have is mixed.
grade-b - High See all 10 studies
It is possible that tyrosine can reduce blood pressure increases during psychological stress, but only a small amount of research in this context has been conducted. For other forms of stress, hypertension, and healthy participants, improvements haven't been observed.
grade-b - Very High See all 15 studies
Consistently no effect of acute dosing during stressful or relaxed conditions.
grade-c Minor Very High See all 5 studies
It seems to be able to preserve attention while under stress but hasn't shown effects besides that.
grade-c
Minor
- See all 6 studies
It's unclear when it increases it, decreases it, or has no effect. More research is needed.
grade-c Minor Very High See 2 studies
Perceptions of stress during acute stressors, as well as related symptoms of acute stress, appear to be reduced following tyrosine ingestion
grade-c Minor Moderate See 2 studies
There appears to be an increase in subjective well being during stress when tyrosine is preloaded (perhaps secondary to the antistress effects of tyrosine), although this is not overly reliable
grade-c Minor - See study
More evidence is needed, one study found broad improvements but the difference wasn't statistically significant.
grade-c - Very High See all 5 studies
No apparent effect of acute dosing. It's unclear if chronic dosing is effective.
grade-c - Very High See all 4 studies
No apparent effect on glucose during exercise from acute dosing. It's unclear if chronic dosing could have effects on general glucose levels.
grade-c - Very High See all 4 studies
No apparent effect from acute dosing before exercise.
grade-c - Very High See all 3 studies
Depressive symptoms that occur during acute stressors have not been affected by tyrosine supplementation. Chronic depression hasn't yet been researched.
grade-c - Very High See all 3 studies
No significant influence has been noted on fatigue from L-Tyrosine supplementation during acute stresses
grade-c - - See study
grade-c - - See 2 studies
A benefit was observed in two studies, one during multitasking, and the other during stress. More research is needed.
grade-c - Very High See all 4 studies
No apparent effect when taken before exercise.
grade-d Notable - See study
Improvement in endurance under high heat conditions was noted in one study.
grade-d
Minor
Low See all 3 studies
Inconsistent effects, and more research is needed to explain the inconsistency.
grade-d Minor - See study
One study found an increase during severe psychological stress. More research is needed before we can put any stock in it.
grade-d Minor Moderate See 2 studies
Mixed evidence but one study found a notable increase.
grade-d Minor - See study
An improvement was found in one study when 2 g was taken acutely.
grade-d Minor - See study
One study found an increase when taken acutely before lower body negative pressure stress. However, it didn't seem to affect the change due to it.
grade-d Minor Moderate See 2 studies
One study found a potential impairment during lower body negative pressure stress, but another didn't find an effect. More research is needed.
grade-d - Very High See 2 studies
No apparent effect from acute dosing before exercise or cognitive testing.
grade-d - Moderate See 2 studies
One study found an improvement in cold conditions whereas another didn't find an improvement during warm conditions.
grade-d - High See all 3 studies
Overall no apparent effect.
grade-d - High See all 4 studies
Overall no apparent effect,
grade-d - - See study
No apparent effect from acute dosing before exercise.
grade-d - - See study
No apparent effect in schizophrenia.
grade-d - - See 2 studies
grade-d - Very High See 2 studies
No apparent effect from acute dosing before exercise.
grade-d - - See study
No apparent effect from acute dosing before exercise.
grade-d - Very High See all 3 studies
No apparent effect from acute dosing before exercise.
grade-d - - See study
No apparent effect in one study.
grade-d - - See study
No apparent effect from one study.
grade-d - - See study
No apparent effect in general, though the study found a worsening of smooth-pursuit eye movement when taking tyrosine.
grade-d - - See study
grade-d - Very High See 2 studies
No apparent effect when taken before exercise.
grade-d - - See study
No apparent effect in one study.
grade-d - - See study
No apparent effect when taken before exercise.
grade-d - Moderate See 2 studies
Mixed evidence. One study found an increase during exercise under warm conditions, whereas another found no effect during psychological stress.
grade-d - - See study
No apparent effect when taken acutely (of course).

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Things to Note

Primary Function:

Do Not Confuse With

Taurine

Caution Notice

L-tyrosine has several theoretical interactions where caution is warranted. It may raise thyroid hormone production since it is a precursor for its synthesis, so those with a hyperactive thyroid should be wary. Also, it may interact with MAOIs leading to a hypertensive crisis. Additionally, it could theoretically block the uptake from the gut of some drugs that resemble certain amino acids such as levodopa. Finally, since it is a precursor for stimulatory neurotransmitters, it may interact with or potentiate the effects of other drugs or supplements that are stimulatory as well, along with drugs that affect dopamine and norepinephrine productions.

  • L-tyrosine is stimulatory. It may thus theoretically interact with other stimulatory pharmaceuticals or supplements.

  • L-tyrosine can theoretically interact with the absorption of some drugs that look like certain amino acids (e.g. levodopa). It can also theoretically interact with MAOIs and exacerbate hyperthyroid conditions.

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Click here to see all 68 references.