Tyrosine is a nonessential amino acid the body makes from another amino acid called phenylalanine. It is an essential component for the production of several important brain chemicals called neurotransmitters, including epinephrine, norepinephrine, and dopamine. Neurotransmitters help nerve cells communicate and influence mood. Tyrosine also helps produce melanin, the pigment responsible for hair and skin color. It helps in the function of organs responsible for making and regulating hormones, including the adrenal, thyroid, and pituitary glands. It is involved in the structure of almost every protein in the body.

It's rare to be deficient in tyrosine. Low levels have been associated with low blood pressure, low body temperature, and an underactive thyroid. This does not mean, however, that taking tyrosine supplements will help any of these conditions.

Phenylketonuria (PKU)

This serious condition occurs in people whose bodies can't use the amino acid phenylalanine. It can lead to brain damage, including intellectual disability. People with PKU must avoid any phenylalanine in their diets. Because tyrosine is made from phenylalanine, people with PKU can be deficient in tyrosine. Tyrosine is used in protein supplements for people with PKU, but most doctors don't recommend more tyrosine supplements. If you have PKU, your doctor will determine if you need more tyrosine and how much.

Stress

Tyrosine is involved in the production of the stress neurotransmitters epinephrine and norepinephrine. Some researchers believe that, under stress, the body isn't able to make enough tyrosine from phenylalanine. Some animal and human studies suggest that tyrosine supplements may help improve memory and performance under psychological stress. More research is needed.

Sleep deprivation

One study suggests that taking tyrosine may help you be more alert after sleep deprivation. More research is needed.

Other

Some athletes claim that tyrosine helps their performance. However, there is no proof that this claim is true or safe.

Because tyrosine helps the body produce the mood-influencing chemical dopamine, and because people who are depressed often have low levels of tyrosine, researchers thought that tyrosine might help treat depression. However, studies have found that it has no effect.

Preliminary research suggests that tyrosine kinase inhibitors may play a role in the treatment of thyroid cancer. Other studies suggest tyrosine kinase inhibitors may help improve lung function among people who have lung cancer or pulminary fibrosis. More research is needed.

Tyrosine is found in soy products, chicken, turkey, fish, peanuts, almonds, avocados, bananas, milk, cheese, yogurt, cottage cheese, lima beans, pumpkin seeds, and sesame seeds.

Tyrosine is also available as a dietary supplement, in capsule or tablet form.

Take tyrosine supplements 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

Don't give tyrosine supplements to a child without first asking your doctor.

Adult

Doses vary. Talk to your nutritionist or doctor about what dose is right for you. To treat symptoms of sleep deprivation, one study used 150 mg per kilogram of body weight per day.

Because of the potential for side effects and interactions with medications, you should take dietary supplements only under the supervision of a knowledgeable health care provider.

People who have migraine headaches should avoid tyrosine, as it can trigger migraine headaches and stomach upset.

People with hyperthyroidism or Graves disease should avoid tyrosine supplements because tyrosine may increase levels of thyroid hormone.

If you are being treated with any of the following medications, you should not use tyrosine supplements without first talking to your health care provider.

Monoamine Oxidase Inhibitors (MAOIs) -- Tyrosine may cause a severe increase in blood pressure in people taking antidepressant medications known as MAOIs. This rapid increase in blood pressure, also called "hypertensive crisis,” can lead to a heart attack or stroke. People taking MAOIs should avoid foods and supplements containing tyrosine. MAOIs include:

• Isocarboxazid (Marplan)
• Phenelzine (Nardil)
• Tranylcypromine (Parnate)
• Selegiline

Thyroid hormone -- Tyrosine is a precursor to thyroid hormone, so it might raise levels too high when taken with synthetic thyroid hormones.

Levodopa (L-dopa) -- Tyrosine should not be taken at the same time as levodopa, a medication used to treat Parkinson's disease. Levodopa may interfere with the absorption of tyrosine.

Carhill AA, et al. The noninvestigational use of tyrosine kinase inhibitors in thyroid cancer: establishing a standard for patient safety and monitoring. J Clin Endocrinol Metab. 2013;98(1):31-42.

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

Hoffman JR, Ratamess NA, Gonzalez A, Beller NA, Hoffman MW, Olson M, Purpura M, Jäger R. The effects of acute and prolonged CRAM supplementation on reaction time and subjective measures of focus and alertness in healthy college students. J Int Soc Sports Nutr. 2010 Dec 15;7:39.

Kliegman R, Behrman R, Jenson H, Stanton B. Nelson Textbook of Pediatrics, 19th ed. Philadelphia, PA: Saunders Elsevier; 2011.

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]

Melmed: Williams Textbook of Endocrinology, 12th ed. Philadelphia, PA: Saunders Elsevier; 2011.

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

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

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

Richeldi L, et al. Efficacy of a tyrosine kinase inhibitor in idiopathic pulmonary fibrosis. N Engl J Med. 2011;365(12):1079-87.

Thomas A, Rajan A, giaccone G. Tyrosine Kinase Inhibitors in Lung Cancer. Hematology/Oncology Clinics of North America. 2012;26(3).

Tumilty L, Davison G, Beckmann M, Thatcher R. Oral tyrosine supplementation improves exercise capacity in the heat. Eur J Appl Physiol. 2011 Mar 25. [Epub ahead of print]

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.

Webster D, Wildgoose J. Tyrosine supplementation for phenylketonuria. Cochrane Database Syst Rev. 2010 Aug 4;(8):CD001507. Review.

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