Tyrosine

Related Terms

2-Amino-3-(4-hydroxyphenyl)propionic acid, 4-hydroxyphenylalanine, acetyl-L-tyrosine, glycyl-L-tyrosine, levotyrosine, L-tyrosine, m-tyrosine, N-acetyl-L-tyrosine, N-acetyltyrosine, para-hydroxyphenylalanine, para-tyr, p-tyr, Tyr, tyrosinum.

Background

Tyrosine is a nonessential amino acid, meaning that the body normally makes enough of it. Tyrosine is made from phenylalanine, an essential amino acid. Tyrosine is found in soy products, chicken, fish, almonds, avocados, bananas, dairy products, lima beans, pumpkin seeds, and sesame seeds. However, it is difficult to get enough tyrosine from food for medical purposes. For supplementation, tyrosine may be taken in tablet or capsule form.
Tyrosine may be added to supplements to treat phenylketonuria, a birth defect in which people cannot process phenylalanine. As a result, they cannot make enough tyrosine and there is a buildup of phenylalanine in the body, which may harm the nervous system.
Tyrosine is involved in the production of important chemicals in the body, such as dopamine, epinephrine, and norepinephrine. Tyrosine is thought to improve alertness, enhance mood, lower stress, and promote brain health. It is also believed to increase sex drive and reduce appetite.
Tyrosine is also involved in the production of melanin, a compound that gives skin its color. Because of this, tyrosine is thought to play a role in skin conditions such as albinism (little or no color in the hair, skin, and eyes). It is also involved in the production of thyroid hormones and may be used to treat those with thyroid problems.
Studies have looked at the potential effectiveness of tyrosine for improving brain function and treating depression, sleep disorders, Parkinson's disease, and schizophrenia. However, more research is needed before conclusions may be made.

Evidence Table

These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. GRADE *
These uses have been tested in humans or animals. Safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. GRADE *


Phenylketonuria is a birth defect in which people cannot process phenylalanine, an amino acid. As a result, their bodies cannot make enough tyrosine. Protein supplements containing tyrosine may be used to treat this disorder. However, information is limited. Further research is needed in this area.

 B


Phenylketonuria is a birth defect in which people cannot process phenylalanine, an amino acid. As a result, their bodies cannot make enough tyrosine. Protein supplements containing tyrosine may be used to treat this disorder. However, information is limited. Further research is needed in this area.

 B


Tyrosine has been used in a combination treatment to help reduce stress and withdrawal symptoms in alcoholics. However, the effects of tyrosine alone are unclear. More studies are needed before a conclusion may be made.

 C


Tyrosine has been used in a combination treatment to help reduce stress and withdrawal symptoms in alcoholics. However, the effects of tyrosine alone are unclear. More studies are needed before a conclusion may be made.

 C


Tyrosine has been used in a combination treatment to help people who have Alzheimer's disease or dementia. However, the effects of tyrosine alone are unclear. More studies are needed before a conclusion may be made.

 C


Tyrosine has been used in a combination treatment to help people who have Alzheimer's disease or dementia. However, the effects of tyrosine alone are unclear. More studies are needed before a conclusion may be made.

 C


Several studies have examined the effects of tyrosine supplementation on endurance performance. For many trials, tyrosine lacked evidence of benefit. More well-designed trials are needed before a conclusion may be made.

 C


Several studies have examined the effects of tyrosine supplementation on endurance performance. For many trials, tyrosine lacked evidence of benefit. More well-designed trials are needed before a conclusion may be made.

 C


Research suggests that people who have ADHD may be deficient in dopamine and norepinephrine. Since tyrosine is involved in the production of these chemicals, it has been suggested as a possible ADHD treatment. However, more studies are needed before a conclusion may be made.

 C


Research suggests that people who have ADHD may be deficient in dopamine and norepinephrine. Since tyrosine is involved in the production of these chemicals, it has been suggested as a possible ADHD treatment. However, more studies are needed before a conclusion may be made.

 C


Uremia is a complication of kidney disease that may lead to a buildup of waste products and a lower ratio of tyrosine to phenylalanine. Tyrosine supplementation has been suggested as a possible treatment. However, evidence is limited, and more research is needed before conclusions may be made.

 C


Uremia is a complication of kidney disease that may lead to a buildup of waste products and a lower ratio of tyrosine to phenylalanine. Tyrosine supplementation has been suggested as a possible treatment. However, evidence is limited, and more research is needed before conclusions may be made.

 C


Limited research found that tyrosine supplementation lacked effects on symptoms of craving in people with cocaine dependence. More studies are needed before a conclusion may be made.

 C


Limited research found that tyrosine supplementation lacked effects on symptoms of craving in people with cocaine dependence. More studies are needed before a conclusion may be made.

 C


Tyrosine has been studied as a way to improve brain function after stress, such as cold exposure. The results have been mixed. Most research suggests that tyrosine lacks benefit, but some studies report that tyrosine as part of a combination treatment may improve brain-body functions of men living in low-oxygen conditions. More research is needed in this area.

 C


Tyrosine has been studied as a way to improve brain function after stress, such as cold exposure. The results have been mixed. Most research suggests that tyrosine lacks benefit, but some studies report that tyrosine as part of a combination treatment may improve brain-body functions of men living in low-oxygen conditions. More research is needed in this area.

 C


Tyrosine is involved in the production of dopamine, epinephrine, and norepinephrine. These chemicals are thought to be important in controlling depression. Early research suggests that tyrosine may lack benefit for this condition. However, evidence is limited. More research is needed before a conclusion may be made.

 C


Tyrosine is involved in the production of dopamine, epinephrine, and norepinephrine. These chemicals are thought to be important in controlling depression. Early research suggests that tyrosine may lack benefit for this condition. However, evidence is limited. More research is needed before a conclusion may be made.

 C


Early research reports that tyrosine may lack benefit for people who have untreated mild high blood pressure. More research is needed before a conclusion may be made.

 C


Early research reports that tyrosine may lack benefit for people who have untreated mild high blood pressure. More research is needed before a conclusion may be made.

 C


Early studies suggest that tyrosine may have benefits for this condition. However, more research is needed in this area.

 C


Early studies suggest that tyrosine may have benefits for this condition. However, more research is needed in this area.

 C


Early research reports that tyrosine may lack benefit for treating narcolepsy (excessive sleepiness). Tyrosine may lack effects on symptoms such as daytime drowsiness, nighttime sleep, and sleep paralysis (feeling unable to move while falling asleep or waking up). More research is needed in this area.

 C


Early research reports that tyrosine may lack benefit for treating narcolepsy (excessive sleepiness). Tyrosine may lack effects on symptoms such as daytime drowsiness, nighttime sleep, and sleep paralysis (feeling unable to move while falling asleep or waking up). More research is needed in this area.

 C


One study found some evidence of benefit for tyrosine supplementation in people with Parkinson's disease. However, more research is needed before a conclusion may be made.

 C


One study found some evidence of benefit for tyrosine supplementation in people with Parkinson's disease. However, more research is needed before a conclusion may be made.

 C


Early research suggests that tyrosine may lack benefit for symptoms of schizophrenia (a mental disorder affecting thought process). Further research is needed before a conclusion may be made.

 C


Early research suggests that tyrosine may lack benefit for symptoms of schizophrenia (a mental disorder affecting thought process). Further research is needed before a conclusion may be made.

 C


Early research reports that tyrosine may help improve mood during the winter in people living in Antarctica. Further research is needed before a conclusion may be made.

 C


Early research reports that tyrosine may help improve mood during the winter in people living in Antarctica. Further research is needed before a conclusion may be made.

 C


Evidence is lacking in support of using tyrosine supplementation for stress. Further research is needed before a conclusion may be made.

 C


Evidence is lacking in support of using tyrosine supplementation for stress. Further research is needed before a conclusion may be made.

 C


Tyrosine, combined with other chemicals such as caffeine, may help enhance weight loss. However, the effects of tyrosine alone are unclear. More studies using tyrosine alone are needed before a conclusion may be made.

 C


Tyrosine, combined with other chemicals such as caffeine, may help enhance weight loss. However, the effects of tyrosine alone are unclear. More studies using tyrosine alone are needed before a conclusion may be made.

 C
* Key to grades

A: Strong scientific evidence for this use
B: Good scientific evidence for this use
C: Unclear scientific evidence for this use
D: Fair scientific evidence for this use (it may not work)
F: Strong scientific evidence against this use (it likley does not work)
* Key to grades

A: Strong scientific evidence for this use
B: Good scientific evidence for this use
C: Unclear scientific evidence for this use
D: Fair scientific evidence for this use (it may not work)
F: Strong scientific evidence against this use (it likley does not work)

Tradition / Theory

The below uses are based on tradition, scientific theories, or limited research. They often have not been thoroughly tested in humans, and safety and effectiveness have not always been proven. Some of these conditions are potentially serious, and should be evaluated by a qualified healthcare provider. There may be other proposed uses that are not listed below.

Dosing

Adults (18 years and older)
To improve cognitive performance, 100-300 milligrams of tyrosine per kilogram has been taken by mouth daily, sometimes as a food or energy bar. A protein-rich drink containing two grams of tyrosine has been taken by mouth in five daily doses.
To treat depression, 100 milligrams of tyrosine per kilogram has been taken by mouth daily in three divided doses for two weeks.
To treat narcolepsy (excessive sleepiness), 70-80 milligrams of tyrosine has been taken by mouth daily in three doses, adjusted to a final average dose of 100 milligrams per kilogram, for six months.
To treat seasonal affective disorder (SAD), 12 grams of tyrosine mixed in 113 grams of applesauce has been taken by mouth daily for about 92 days in summer and/or about 138 days in winter.

Safety

The U.S. Food and Drug Administration does not strictly regulate herbs and supplements. There is no guarantee of strength, purity or safety of products, and effects may vary. You should always read product labels. If you have a medical condition, or are taking other drugs, herbs, or supplements, you should speak with a qualified healthcare provider before starting a new therapy. Consult a healthcare provider immediately if you experience side effects.

Interactions

Interactions with Drugs
Tyrosine may affect blood pressure. Caution is advised in people taking drugs that affect blood pressure. Caution is advised when taking monoamine oxidase inhibitors (MAOIs) or drugs with similar properties, as taking tyrosine at the same time may cause dangerously high blood pressure.
Tyrosine may interfere with the way the body processes certain drugs using the liver's cytochrome P450 enzyme system. As a result, the levels of these drugs may be increased in the blood and may cause increased effects or potentially serious adverse reactions. People using any medications should check the package insert and speak with a qualified healthcare professional, including a pharmacist, about possible interactions.
Tyrosine may also interact with agents that may affect seizure risk, agents that may prevent nausea and vomiting, agents that may treat abnormal heartbeat, agents that may treat depression, antianxiety agents, antidiabetic agents, antidiarrheal agents, antiulcer and stomach acid-reducing agents, birth control taken by mouth, dexamethasone, eye agents, levodopa, nitisinone, skin agents, stimulants, and thyroid hormones.

Attribution

This information is based on a systematic review of scientific literature edited and peer-reviewed by contributors to the Natural Standard Research Collaboration (www.naturalstandard.com).

Bibliography

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Vrshek-Schallhorn S, Wahlstrom D, Benolkin K, et al. Affective Bias and Response Modulation Following Tyrosine Depletion in Healthy Adults. Neuropsychopharmacology 2006;31(11):2523-2536.
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