Tyrosine is an amino acid that the body makes from a different amino acid called phenylalanine. Foods that contain phenylalanine include soy, chicken, milk, sesame seeds, and lima beans.

Tyrosine may improve mood, cognition, or concentration. A deficiency in this amino acid may cause low blood pressure and a low body temperature.

People with the genetic disorder phenylketonuria (PKU) have a high risk of tyrosine deficiency because the body does not convert phenylalanine to tyrosine.

Person cutting tofu, a food high in tyrosine.Share on Pinterest
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Tyrosine is a nonessential amino acid. The term nonessential means that a person does not need to get it through the diet, not that it is unimportant to health. The body can manufacture tyrosine naturally when a person gets sufficient quantities of the amino acid phenylalanine.

The disease PKU, which is present at birth, causes a dangerous buildup of phenylalanine.

Children and adults with this disorder should limit their intake of foods containing phenylalanine. This puts them at risk of tyrosine deficiency because the body does not convert phenylalanine to tyrosine.

Tyrosine helps the body make several important neurotransmitters, including those below. These chemicals help carry nerve signals across a synapse, playing a vital role in many important functions.

  • Epinephrine: Also known as adrenaline, this chemical plays a critical role in the fight-or-flight response.
  • Norepinephrine: The body releases this chemical along with epinephrine to increase heart rate and support the fight-or-flight response. It also provides energy by breaking down fat and increasing blood sugar.
  • Dopamine: This neurotransmitter helps support feelings of pleasure, reward, and motivation. Its absence may contribute to sexual dysfunction, depression, addiction, and attention.

When the body cannot produce these neurotransmitters in sufficient quantities, a person may experience concentration issues, mood changes, and difficulty managing stress.

Some research also suggests that tyrosine supplements may offer health benefits.

Early research on tyrosine suggests that it may help counteract the effects of stress by supporting neurotransmitter function, attention, and cognition. For example, it may help prevent sudden declines in function when a person is under physical stress from an illness or exhaustion.

A 2015 study supports this claim, suggesting that when stress depletes neurotransmitters, tyrosine supplements may improve cognition. However, this effect only occurs when underlying neurotransmitter function is healthy, and the levels of neurotransmitters such as dopamine have become temporarily depleted.

Not all research supports this idea, though. A 2018 study of tyrosine supplements in healthy older adults found that the supplement actually harmed some cognitive functions in people aged 61–72 years.

The authors of the study suggest that tyrosine supplements may induce an overdose in older people, causing harmful effects. They emphasize that most prior research on tyrosine has looked at young people and that these results may not be applicable to the wider population.

A 2017 study that included adults aged 24–40 years and older adults aged 61–88 years showed benefits in both groups. The researchers found that high tyrosine consumption correlated with better scores on a cognitive assessment regardless of age.

However, as the study looked at dietary tyrosine, it does not provide guidance about the potential risks and benefits of tyrosine supplements.

Some research has found that tyrosine kinase inhibitors could play a role in the treatment of thyroid or lung cancer. A kinase inhibitor blocks the effects of kinases, which add phosphate to a protein and potentially change its function.

This suggests, but does not prove, that changes in how tyrosine behaves may play a role in the development of certain cancers.

High protein foods tend to be high in amino acids.

Some foods that are rich in phenylalanine, which the body needs to synthesize tyrosine, include:

  • soy products, such as soybeans, tofu, and soy milk
  • fish and meat, including chicken, turkey, and pork
  • eggs and dairy products, such as milk and cheese
  • seeds, including pumpkin and sesame seeds
  • beans, such as lima beans

Vegetarians and vegans may need to focus on eating more high protein foods, such as tofu, to ensure that they get enough tyrosine and other amino acids.

A doctor or dietitian can offer advice on how people with PKU can get enough tyrosine without eating phenylalanine.

A person can also take a tyrosine supplement, but the right dosage varies among individuals. It is important to talk with a doctor before taking any new supplements.

Tyrosine is vital for good health, and its absence can mean that the body does not make enough neurotransmitters to support attention, cognition, and mood.

Whole foods rich in phenylalanine can help a person meet their daily tyrosine needs, but meeting these needs can be difficult for people with PKU. A doctor can help these individuals understand how to get enough tyrosine.

People without PKU considering tyrosine supplements should weigh the risks and benefits, especially if they are over the age of 60 years, since some research suggests high levels of tyrosine may be harmful after this age.