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Tyrosine

Tyrosine

While some complementary and alternative techniques have been studied scientifically, high-quality data regarding safety, effectiveness, and mechanism of action are limited or controversial for most therapies. Whenever possible, it is recommended that practitioners be licensed by a recognized professional organization that adheres to clearly published standards. In addition, before starting a new technique or engaging a practitioner, it is recommended that patients speak with their primary healthcare provider(s). Potential benefits, risks (including financial costs), and alternatives should be carefully considered. The below monograph is designed to provide historical background and an overview of clinically-oriented research, and neither advocates for or against the use of a particular therapy.

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.

Scientific Evidence

Uses

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.

B Phenylketonuria (PKU)

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.

C Alcoholism (stress)

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 Alzheimer’s disease

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 Athletic endurance

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 Attention-deficit hyperactivity disorder (ADHD)

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 Blood disorders (uremia)

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 Cocaine dependence

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 Cognitive function

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 Depression

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 High blood pressure

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 Muscle weakness

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

C Narcolepsy

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 Parkinson’s disease

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 Schizophrenia

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 Seasonal affective disorder

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 Stress

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

C Weight loss

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.

*Key to grades:

Tradition

The below uses are based on tradition or scientific theories. 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 health care professional.

  • Allergies, antioxidant, appetite suppressant, arthritis, communication skills, drug withdrawal (caffeine), energy, erectile dysfunction, fatigue, growth, growth hormone stimulation, hair dye, headache, heart disease, immune stimulant, irritability, libido, nerve disorders, nicotine withdrawal, premenstrual syndrome, skin aging, skin pigmentation disorders (little or no skin color), stroke, vitiligo (white patches on skin).

Dosing

The below doses are based on scientific research, publications, traditional use, or expert opinion. Many herbs and supplements have not been thoroughly tested, and safety and effectiveness may not be proven. Brands may be made differently, with variable ingredients, even within the same brand. The below doses may not apply to all products. You should read product labels, and discuss doses with a qualified healthcare provider before starting therapy.

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.

Children (under 18 years old)

  • To treat muscle weakness, 250-3,000 milligrams of tyrosine has been taken by mouth.

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.

Allergies

  • Avoid in people who are allergic or sensitive to tyrosine or to ingredients found in tyrosine supplements.

Side Effects and Warnings

  • In general, reports of serious side effects after taking tyrosine and long-term effects of high doses of tyrosine (greater than 1,000 milligrams daily) are lacking.
  • Tyrosine is likely to be safe in amounts normally found in food.
  • Tyrosine is possibly safe when taken short-term by adults or when applied to the skin.
  • Tyrosine may cause anxiety, changes in mood (increased irritability, tension, and restlessness), developmental problems, drowsiness, eye problems (such as changes in vision), overstimulation, reduced drooling (in children with nemaline myopathy, a muscle disorder), sleep problems, thickened skin on the hands and feet, and tics.
  • High doses may result in diarrhea, nausea, nervousness, or vomiting.
  • Use cautiously in people who have abnormal heartbeat or those using agents that may treat heart disorders. Tyrosine may cause abnormal or rapid heartbeat.
  • Tyrosine may affect blood pressure. Caution is advised in people who have blood pressure disorders or those taking drugs or herbs and supplements that affect blood pressure.
  • Caution is advised when taking monoamine oxidase inhibitor drugs (MAOIs) or drugs with similar properties, as tyrosine may cause dangerously high blood pressure when taken at the same time as these drugs.
  • Use cautiously in people who have thyroid disorders or Graves’ disease. Tyrosine supplementation may affect thyroxine levels and worsen symptoms.
  • Use cautiously in people who have migraine headaches. Tyrosine may act as a trigger.
  • Use cautiously in people who have stomach disorders or symptoms. Tyrosine may cause diarrhea, gas, heartburn, nausea, and vomiting.
  • Use cautiously in people who have diabetes or are taking antidiabetic agents. Tyrosine may increase levels of tyrosine in the body.
  • Use cautiously in people who have seizures. Tyrosine may trigger seizures.
  • Use cautiously in people who are taking stimulants or agents to treat anxiety.
  • Use cautiously in people who may have a high risk of skin cancer. Tyrosine may promote cancer cell division.
  • Use cautiously in pregnant and breastfeeding women, due to a lack of information.
  • Avoid in people who are allergic or sensitive to tyrosine or to ingredients found in tyrosine supplements.

Pregnancy and Breastfeeding

  • There is a lack of scientific evidence on the use of tyrosine during pregnancy or breastfeeding.

Interactions

Most herbs and supplements have not been thoroughly tested for interactions with other herbs, supplements, drugs, or foods. The interactions listed below are based on reports in scientific publications, laboratory experiments, or traditional use. 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.

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.

Interactions with Herbs and Dietary Supplements

  • Tyrosine may affect blood pressure. Caution is advised in people taking herbs or supplements that affect blood pressure. Caution is advised when taking herbs or supplements that have similar properties to monoamine oxidase inhibitors (MAOIs), as taking tyrosine at the same time may cause dangerously high blood pressure.
  • Tyrosine may interfere with the way the body processes certain herbs or supplements using the liver’s cytochrome P450 enzyme system. As a result, the levels of other herbs or supplements may become too high in the blood. It may also alter the effects that other herbs or supplements possibly have on the P450 system.
  • Tyrosine may also interact with amino acids, antianxiety agents, antidiabetic herbs and supplements, antidiarrheal herbs and supplements, antiulcer and stomach acid-reducing herbs and supplements, aspartame, birth control taken by mouth, calcium and calcium-containing foods, capsaicin, copper, folic acid, green tea and green tea extract, herbs and supplements that may affect seizure risk, herbs and supplements that may prevent nausea and vomiting, herbs and supplements that may treat abnormal heartbeat, herbs and supplements that may treat depression, herbs and supplements that may treat eye disorders, herbs and supplements that may treat skin disorders, phenylalanine, protein, stimulants, thyroid agents, and vitamin B6.

Author Information

  • 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).

References

Natural Standard developed the above evidence-based information based on a thorough systematic review of the available scientific articles. For comprehensive information about alternative and complementary therapies on the professional level, go to www.naturalstandard.com. Selected references are listed below.

  1. Barrett SP and Leyton M. Acute phenylalanine/tyrosine depletion: A new method to study the role of catecholamines in psychiatric disorders. Primary Psychiatry 2004;11(6):37-41.
  2. Belza A, Frandsen E, Kondrup J. Body fat loss achieved by stimulation of thermogenesis by a combination of bioactive food ingredients: a placebo-controlled, double-blind 8-week intervention in obese subjects. Int.J.Obes.(Lond) 2007;31(1):121-130. View Abstract
  3. Bjerkensted L, Farde L, Terenius L, et al. Support for limited brain availability of tyrosine in patients with schizophrenia. International Journal of Neuropsychopharmacology 2006;9(2):247-255.
  4. Ellis KA, Mehta MA, Murthy PJ, et al. Tyrosine depletion alters cortical and limbic blood flow but does not modulate spatial working memory performance or task-related blood flow in humans. Human Brain Mapping 2007;28(11):1136-1149.
  5. Hitsman B, MacKillop J, Lingford-Hughes A, et al. Effects of acute tyrosine/phenylalanine depletion on the selective processing of smoking-related cues and the relative value of cigarettes in smokers. Psychopharmacology 2008;196(4):611-621.
  6. Leyton M, Dagher A, Boileau I, et al. Decreasing Amphetamine-Induced Dopamine Release by Acute Phenylalanine/Tyrosine Depletion: A PET/ [¹¹C]Raclopride Study in Healthy Men. Neuropsychopharmacology 2004;29(2):427-432.
  7. Lythe KE, Anderson IM, Deakin JFW, et al. Lack of behavioural effects after acute tyrosine depletion in healthy volunteers. Journal of Psychopharmacology 2005;19(1):5-11.
  8. Magill RA, Waters WF, Bray GA, et al. Effects of tyrosine, phentermine, caffeine D-amphetamine, and placebo on cognitive and motor performance deficits during sleep deprivation. Nutr.Neurosci. 2003;6(4):237-246. View Abstract
  9. McLean A, Rubinsztein JS, Robbins TW, et al. The effects of tyrosine depletion in normal healthy volunteers: Implications for unipolar depression. Psychopharmacology 2004;171(3):286-297.
  10. Montgomery AJ, McTavish SFB, Cowen PJ, et al. Reduction of Brain Dopamine Concentration With Dietary Tyrosine Plus Phenylalanine Depletion: An [¹¹C]Raclopride PET Study. American Journal of Psychiatry 2003;160(10):1887-1889.
  11. Munafo MR, Mannie ZN, Cowen PJ, et al. Journal of Effects of acute tyrosine depletion on subjective craving and selective processing of smoking-related cues in abstinent cigarette smokers. Psychopharmacology 2007;21(8):805-814.
  12. Ryan MM, Sy C, Rudge S, et al. Dietary L-tyrosine supplementation in nemaline myopathy. J.Child Neurol. 2008;23(6):609-613. View Abstract
  13. Sutton EE, Coill MR, Deuster PA. Ingestion of tyrosine: effects on endurance, muscle strength, and anaerobic performance. Int.J.Sport Nutr.Exerc.Metab 2005;15(2):173-185. View Abstract
  14. 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.
  15. Young SN. Psychopharmacology for the clinician: Psychopharmacologie pratique: L-Tyrosine to alleviate the effects of stress? Journal of Psychiatry & Neuroscience 2007;32(3):224.

The information in this monograph is intended for informational purposes only, and is meant to help users better understand health concerns. Information is based on review of scientific research data, historical practice patterns, and clinical experience. This information should not be interpreted as specific medical advice. Users should consult with a qualified healthcare provider for specific questions regarding therapies, diagnosis and/or health conditions, prior to making therapeutic decisions.