L Tyrosine
Tyrosine (Tyr) is one of the amino acids, which are the building blocks of protein. The body makes tyrosine from another amino acid called phenylalanine. Tyrosine can also be found in dairy products, meats, fish, eggs, nuts, beans, oats, and wheat. Tyrosine is used in protein supplements to treat an inherited disorder called phenylketonuria (PKU). People who have this problem can’t process phenylalanine properly, so as a result they can’t make tyrosine. To meet their bodies’ needs, supplemental tyrosine is given. People take tyrosine for depression, attention deficit disorder (ADD), attention deficit-hyperactivity disorder (ADHD), the inability to stay awake (narcolepsy), and improving alertness following sleep deprivation. It is also used for stress, premenstrual syndrome (PMS), Parkinson's disease, Alzheimer's disease, chronic fatigue syndrome (CFS), alcohol and cocaine withdrawal, heart disease and stroke, ED (erectile dysfunction), loss of interest in sex, schizophrenia, and as a suntan agent and appetite suppressant. Some people also apply tyrosine to the skin to reduce age-related wrinkles.

What is L-Tyrosine?
Other names
2-Amino-3-(4-hydroxyphenyl) propanoic acid

Tyrosine is non-essential amino acid because it is synthesized in the body from phenylalanine. Tyrosine has a sparing action, because if tyrosine is fed then phenylalanine- need of the body is decreased. Tyrosine has got an immense metabolic role in the body. It is ketogenic as well as glycogenic. Both phenylalanine and tyrosine are metabolized through the common pathways. Phenylalanine is initially but irreversibly hydroxylated to tyrosine. Tyrosine then undergoes series of metabolic changes leading to the formation of hormones and melanin.

Tyrosine was first isolated from casein in 1849 and is abundant in insulin as well as the enzyme papain and can be synthesized from the amino acid phenylalanine in the body. It is a precursor of the neurotransmitters epinephrine, nor epinephrine and dopamine, all of them extremely important in the brain and transmits nerve impulses and prevents depression. Dopamine is also vital to mental function and seems to play a role in sex drive.

L-Tyrosine is formed by skin cells into melanin, the dark pigment that protects against the harmful effects of ultraviolet light. Thyroid hormones, which have a role in almost every process in the body, also contain tyrosine as part of their structure.

Tyrosine and tryptophan have with been used with some success in the treatment of cocaine abuse and in another study it was combined with the antidepressant Imipramine to treat chronic cocaine abuse where it was reported that the combination blocked the cocaine high and prevented the severe depression that accompanies withdrawal.

How is it Made?
In plants and most microorganisms, tyr is produced via prephenate, an intermediate on the shikimate pathway. Prephenate is oxidatively decarboxylated with retention of the hydroxyl group to give p-hydroxyphenylpyruvate, which is transaminated using glutamate as the nitrogen source to give tyrosine and α-ketoglutarate.

Mammals synthesize tyrosine from the essential amino acid phenylalanine (phe), which is derived from food. The conversion of phe to tyr is catalyzed by the enzyme phenylalanine hydroxylase, a monooxygenase. This enzyme catalyzes the reaction causing the addition of an hydroxyl group to the end of the 6-carbon aromatic ring of phenylalanine, such that it becomes tyrosine.

Where is it Found?
Tyrosine, which can be synthesized in the body from phenylalanine, is found in many high protein food products such as soy products, chicken, turkey, fish, peanuts, almonds, avocados, milk, cheese, yogurt, cottage cheese, lima beans, pumpkin seeds, and sesame seeds.

Benefits / Uses

arw L-tyrosine is also important for making neurotransmitters, which are small chemicals that nerves use to communicate with each other. L-tyrosine is used to make many different neurotransmitters, including dopamine, norepeinephrine and epinephrine (also known as adrenaline).

arw There has been some research that indicates L-tyrosine may be able to help treat depression. Because L-tyrosine is used to make norepinephrine, it's thought that supplementation of L-tyrosine could raise norepinephrine levels. Because medications that raise norepinephrine levels are often used to treat depression, it's theorized that L-tyrosine could have a similar effect. But the evidence for this has been mixed at best.

arw Because L-tyrosine is also able to be made into dopamine, it has been investigated as a possible treatment for Alzheimer's. One of the hallmarks of Alzheimer's is a decrease in dopamine levels; many medications are used to try to increase these levels. This treatment has been found to increase levels of dopamine but doesn't always result in clinical improvement.
Tyrosine supplements should be taken at least 30 minutes before meals, divided into 3 daily doses. Taking vitamins B6, B9 (folate), and copper along with tyrosine helps the body convert tyrosine into important brain chemicals.

Pediatric - There is no specific dietary recommendation for tyrosine. Talk to your doctor before giving a child any dietary supplement.

Adult - Doses vary. Talk to your nutritionist or doctor about what dose is right for you. Most health professionals recommend a dose of 500 - 1,000 mg 3 times per day (before each of the 3 meals). To treat symptoms of sleep deprivation, most doctors recommend 150 mg per kilogram of body weight, per day, has been used.
Possible Side-Effects / Precautions / Possible Interactions
Tyrosine is likely safe in food amounts and possibly safe when taken by adults short-term in medicinal amounts or applied to the skin. Tyrosine seems to be safe when used in doses up to 150 mg/kg per day for up to 3 months. Side-effects such as nausea, headache, fatigue, heartburn, and joint pain have been reported in some cases.

Special Precautions & Warnings:
Pregnancy and breast-feeding: Not enough is known about the safety of using tyrosine during pregnancy and breast-feeding. Stay on the safe side and avoid use.

Overactive thyroid (hyperthyroidism) or Graves disease: The body uses tyrosine to make thyroxine, a thyroid hormone. Taking extra tyrosine might increase thyroxine levels too much, making hyperthyroidism and Graves disease worse.
If you have one of these conditions, don’t take tyrosine supplements.

Research Studies / References

arw Levodopa interacts with tyrosine.

arw Tyrosine might decrease how much levodopa the body absorbs. By decreasing how much levodopa the body absorbs, tyrosine might decrease the effectiveness of levodopa. Do not take tyrosine and levodopa at the same time.

arw Thyroid hormone interacts with tyrosine.

arw The body naturally produces thyroid hormones. Tyrosine might increase how much thyroid hormone the body produces. Taking tyrosine with thyroid hormone pills might cause there to be too much thyroid hormone. This could increase the effects and side effects of thyroid hormones.

arw Awad AG. Diet and drug interactions in the treatment of mental illness -- a review. Can J Psychiatry. 1984;29:609-613.

arw Camacho F, Mazuecos J. Treatment of vitiligo with oral and topical phenylalanine: 6 years of experience. Arch Dermatol. 1999;135:216-217

arw Chakraborty DP, Roy S, Chakroborty AK. Vitiligo, psoralen, and meanogenesis: some observations and understanding. Pigment Cell Res. 1996;9(3):107-116.

arw Chiaroni P, Azorin JM, Bovier P, et al. A multivariate analysis of red blood cell membrane transports and plasma levels of L-tyrosine and L-tryptophan in depressed patients before treatment and after clinical improvement. Neuropsychobiology. 1990;23(1):1-7.
arw Deijen JB, Orlebeke JF. Effect of tyrosine on cognitive function and blood pressure under stress. Brain Res Bull. 1994;33(3):319-323.

arw Fernstrom JD. Can nutrient supplements modify brain function? Am J Clin Nutr. 2000;71(6 Suppl):1669S-1675S.

arw Fugh-Berman A, Cott JM. Dietary supplements and natural products as psychotherapeutic agents. Psychosom Med. 1999;61:712-728.

arw Gelenberg AJ, Wojcik JD, Falk WE, et al. Tyrosine for depression: a double-blind trial. J Affect Disord. 1990;19:125-132.

arw Growdon JH, Melamed E, Logue M, et al. Effects of oral L-tyrosine administration on CSF tyrosine and homovanillic acid levels in patients with Parkinson's disease. Life Sci. 1982;30:827-832.

arw Kelly GS. Nutritional and botanical interventions to assist with the adaptation to stress. Altern Med Rev. 1999;4940;249-265.

arw Kirschmann GJ and Kirschmann JD. Nutrition Almanac, 4th ed. New York, NY: McGraw-Hill;1966:304.

arw Kliegman R, Behrman R, Jenson H, Stanton B. Nelson Textbook of Pediatrics, 18th ed. Philadelphia, PA: Saunders Elsevier; 2007.

arw Koch R. Tyrosine supplementation for phenylketonuria treatment. Am J Clin Nutr. 1996;64(6):974-975.

arw Mahoney CR, Castellani J, Kramer FM, Young A, Lieberman HR. Tyrosine supplementation mitigates working memory decrements during cold exposure. Physiol Behav. 2007 May 22; [Epub ahead of print]

arw Meyers S. Use of neurotransmitter precursors for treatment of depression. Altern Med Rev. 2000;5(1):64-71.

arw Neri DF, Wiegmann D, Stanny RR, Shappell SA, McCardie A, McKay DL. The effects of tyrosine on cognitive performance during extended wakefulness.Aviat Space Environ Med. 1995;66(4):313-319.

arw Parry BL. The role of central serotonergic dysfunction in the aetiology of premenstrual dysphoric disorder: therapeutic implications. CNS Drugs. 2001;15(4):277-285.

arw Pizzorno JE and Murray MT. Textbook of Natural Medicine, Vol 2. New York, NY: Churchill Livingstone; 1999:1049-1059.

arw Poustie VJ, Rutherford P. Tyrosine supplementation for phenylketonuria. Cochrane Database Syst Rev. 2000;(2):CD001507.

arw Riederer P. L-Dopa competes with tyrosine and tryptophan for human brain uptake. Nutr Metab. 1980;24(6):417-423.

arw Smith ML, Hanley WB, Clarke JT, et al. Randomised controlled trial of tyrosine supplementation on neuropsychological performance in phenylketonuria. Arch Dis Child. 1998;78(2):116-121.

arw van Spronsen FJ, van Rijn M, Bekhof J, Koch R, Smit PG. Phenylketonuria: tyrosine supplementation in phenylalanine-restricted diets. Am J Clin Nutr. 2001;73(2):153-157.

arw Wagenmakers AJ. Amino acid supplements to improve athletic performance. Curr Opin Clin Nutr Metab Care. 1999;2(6):539-544.

arw Yehuda S. Possible anti-Parkinson properties of N-(alpha-linolenoyl) tyrosine. A new molecule. Pharmacol Biochem Behav. 2002;72(1-2):7-11.