L-Tyrosine

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a7_3star Reliable and relatively consistent scientific data showing a substantial health benefit.

a7_2star Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.

a7_1star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.

Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.

For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.

This supplement has been used in connection with the following health conditions:

Used for	Amount	Why
Stress	150 mg for every 2.2 lbs (1 kg) of body weight, split into two doses taken before stressful activitiy (take the second dose 40 to 90 minutes after the first)	Occasionally taking this amino acid before a stressful activity may help maintain your mental capacity.
Stress 150 mg for every 2.2 lbs (1 kg) of body weight, split into two doses taken before stressful activitiy (take the second dose 40 to 90 minutes after the first) Tyrosine is an amino acid used by the body to produce certain adrenal stress hormones and chemical messengers in the nervous system (neurotransmitters). Animal research shows that brain levels of these substances decline with stress, and that giving animals tyrosine supplements reverses this decline and improves various tests of performance in stressed animals.¹ In a controlled study, a protein drink containing 10 grams per day of tyrosine was more effective than a carbohydrate drink for improving mental performance scores in a group of cadets taking a stressful six-day combat training course.² A double-blind trial in humans found that one-time administration of 150 mg of tyrosine per 2.2 pounds of body weight helped prevent a decline in mental performance for about three hours during a night of sleep deprivation.³ Single administrations of tyrosine (100 to 150 mg per 2.2 pounds of body weight) have also helped preserve mental performance during physically stressful conditions such as noise or extreme cold in several controlled studies.⁴^{, 5}^{, 6}^{, 7} Learn More

Used for	Amount	Why
Depression	Consult your doctor	Some people with depression have been found to improve with tyrosine.
Depression Consult your doctor The amino acid L-tyrosine can be converted into norepinephrine, a neurotransmitter that affects mood. Women taking oral contraceptives have lower levels of tyrosine, and some researchers think this might be related to depression caused by birth control pills.⁸ L-tyrosine metabolism may also be abnormal in other depressed people⁹ and preliminary research suggests supplementation might help.¹⁰ ^{, 11} Several doctors recommend a 12-week trial of L-tyrosine supplementation for people who are depressed. Published research has used a very high amount—100 mg per 2.2 pounds of body weight (or about 7 grams per day for an average adult). It is not known whether such high amounts are necessary to produce an antidepressant effect. Learn More

Used for	Amount	Why
Phenylketonuria and L-Tyrosine Deficiency	Consult a qualified healthcare practitioner	Supplementing with L-Tyrosine may help prevent a deficiency caused by the PKU diet and improve behavoir.
Phenylketonuria and L-Tyrosine Deficiency Consult a qualified healthcare practitioner PKU results from a deficiency or malfunction of the enzyme, phenylalanine hydroxylase, which converts phenylalanine to . People with PKU have elevated concentrations of phenylalanine and low levels of L-tyrosine, which may contribute to behavior problems. In addition, low L-tyrosine levels in women with PKU may contribute to fetal damage. In some, but not all, double-blind studies, keeping L-tyrosine levels in the normal range by adding supplemental L-tyrosine to the diet improved behavior. In a preliminary study, blood L-tyrosine levels fluctuated significantly in people with PKU, suggesting a need for careful laboratory monitoring of people supplementing with L-tyrosine.

Used for	Amount	Why
Alcohol Withdrawal (Glutamine, Multivitamin, Phenylalanine, Tryptophan)	Refer to label instructions	In double-blind research, alcoholics treated with L-tyrosine combined with DLPA (D,L-phenylalanine), L-glutamine, prescription L-tryptophan, plus a multivitamin had reduced withdrawal symptoms and decreased stress.
Alcohol Withdrawal Kenneth Blum and researchers at the University of Texas have examined neurotransmitter deficiencies in alcoholics. Neurotransmitters are the chemicals the body makes to allow nerve cells to pass messages (of pain, touch, thought, etc.) from cell to cell. Amino acids are the precursors of these neurotransmitters. In double-blind research, a group of alcoholics were treated with 1.5 grams of D,L-phenylalanine (DLPA), 900 mg of L-tyrosine, 300 mg of L-glutamine, and 400 mg of L-tryptophan (now available only by prescription) per day, plus a multivitamin-mineral supplement.¹² This nutritional supplement regimen led to a significant reduction in withdrawal symptoms and decreased stress in alcoholics compared to the effects of placebo. Learn More

Used for	Amount	Why
Parkinson’s Disease	Refer to label instructions	L-tyrosine is the direct precursor to L-dopa and therefore could be an alternative to L-dopa therapy, however, it should not be taken with L-dopa as it may interfere with L-dopa transport to the brain.
Parkinson’s Disease L-tyrosine is the direct precursor to L-dopa. Theoretically, supplementing L-tyrosine could be an alternative to L-dopa therapy; however, L-tyrosine should not be taken with L-dopa as it may interfere with the transport of L-dopa to the brain.¹³ One small preliminary trial demonstrated that some people with Parkinson’s disease who supplemented with L-tyrosine (45 mg per pound of body weight) for three years had better clinical results and fewer side effects than did patients using L-dopa.¹⁴ Until these findings are confirmed, L-tyrosine should not be used as a replacement for, or in addition to, L-dopa. Learn More

Also indexed as:

L-tyrosine,
tyrosine

About this treatment

How to Use It

Most people should not supplement with L-tyrosine. Some human research with people suffering from a variety of conditions used 100 mg per 2.2 pounds of body weight, equivalent to about 7 grams per day for an average-sized person. The appropriate amount to use in people with PKU is not known, therefore, the monitoring of blood levels by a physician is recommended.

Where to Find It

Dairy products, meats, fish, wheat, oats, and most other protein-containing foods contain tyrosine.

Possible Deficiencies

Some people affected by PKU are deficient in tyrosine. Tyrosine levels are occasionally low in depressed people. Any person losing large amounts of protein, such as those with some kidney diseases, may be deficient in several amino acids, including tyrosine.

Interactions

Last Review: 05-11-2011

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The information presented in Aisle7 is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires June 2011.

© 1995-2011 Healthwise, Incorporated. Healthwise, Healthwise for every health decision, and the Healthwise logo are trademarks of Healthwise, Incorporated. This information does not replace the advice of a doctor. Healthwise, Incorporated disclaims any warranty or liability for your use of this information. Your use of this information means that you agree to the Terms of Use. How this information was developed to help you make better health decisions.

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