L-tyrosine is one form of the amino acid tyrosine. It is a non-essential amino acid, meaning that you don't have to get it from food. The body manufactures it, using another amino acid, phenylalanine. You may see tyrosine sold in supplement form with or without the "L."
Tyrosine is in all tissues of the human body and in most of its fluids. It helps the body build proteins in your body, and produce enzymes, thyroid hormones, and the skin pigment melanin. It also helps the body produce neurotransmitters that help nerve cells communicate. Tyrosine is particularly important in the production of epinephrine, norepinephrine, and dopamine. It helps form important brain chemicals that affect mood and sleep. Nutrition Supplements
Most people do not need to take L-tyrosine because their bodies have a mechanism for regulating tyrosine supply. If you do not consume enough tyrosine from food, your body can make more. If you consume too much, your body will break it down and get rid of it.
Although most people do not need to take L-tyrosine, it may be beneficial in certain circumstances, including these:
For a few people, tyrosine is an essential amino acid. These are people who have phenylketonuria (PKU). PKU is a serious condition in which phenylalanine builds up in the body. The main treatment for PKU is restricting dietary sources of phenylalanine. Treatment might also include the use of L-tyrosine as a supplement.
Treatment with tyrosine may help humans perform in stressful situations, such as being exposed to extreme weather or being asked to perform certain cognitive tasks. In several studies, those taking tyrosine did not exhibit the processing problems or the memory deficits that would normally occur in difficult situations.
Tyrosine may also help you stay mentally sharp when you have lost sleep. In one study, subjects were kept awake for over 24 hours. Those who took tyrosine performed much better on two types of tasks than those who took a placebo. The effect lasted around three hours.
Because tyrosine is turned into the brain chemicals dopamine and norepinephrine, it may play a role in relieving depression. An analysis of several studies found that tyrosine might be effective in treating mild-to-moderate depression.
Some children and adults take tyrosine for ADHD. But studies have not shown that it helps.
People also take tyrosine for other reasons, such as easing PMS symptoms and boosting libido. For now, we don't know if tyrosine helps with these conditions.
L-tyrosine is rated as likely or possibly safe at most dosages, but you should still talk to your doctor before taking it. It can interact with medicines, including some medications taken for thyroid problems or depression, and with levodopa, taken for Parkinson's disease.
Tyrosine supplements can cause insomnia, restlessness, palpitations, headache, upset stomach, and heartburn.
Women who are pregnant or breastfeeding should not take L-tyrosine. Also, you should not take it if you have these conditions:
Since tyrosine is involved in the production of thyroid hormones, you should not use L-tyrosine if you have a thyroid condition such as hyperthyroidism or Graves disease. It could cause your levels to go too high.
Some tyrosine is converted into the neurotransmitter epinephrine. During this process, a substance called tyramine is created. Tyramine can trigger a migraine headache by causing blood vessels to constrict and then dilate. For this reason, those who are susceptible to migraines should not take L-tyrosine.
A typical dosage for L-tyrosine is 150 milligrams (mg) daily. You should take tyrosine supplements before meals, preferably divided into three daily doses. Your body might use tyrosine more effectively if you take it with vitamin B6, folate, and copper.
Tyrosine is abundant in many foods, especially traditional sources of protein like peanuts, fish, chicken, turkey, soy, eggs, and cottage cheese. It’s also in pumpkin seeds, oats, wheat, beans, sesame seeds, avocado, and bananas.
Supplements are not regulated by the FDA in the same way food and drugs are. The FDA does not review these supplements for safety or efficacy before they hit the market.
Alternative Medical Review: "Use of neurotransmitter precursors for treatment of depression."
The American Journal of Clinical Nutrition: "Phenylketonuria: tyrosine supplementation in phenylalanine-restricted diets."
Aviation, Space, and Environmental Medicine: "The effects of tyrosine on cognitive performance during extended wakefulness."
Kapalka, G. Nutritional and Herbal Therapies for Children and Adolescents, Academic Press, 2010.
Pharmacology, Biochemistry, and Behavior: "Behavioral and cognitive effects of tyrosine intake in healthy human adults."
Natural Medicines Comprehensive Database: "Tyrosine."
NYU Langone Medical Center: "Tyrosine."
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