Everything You Need To Know about Tyrosine

L-tyrosine, or tyrosine, is a non-essential amino acid naturally made in the body from the essential amino acid phenylalanine. It plays a vital role in many body functions, including creating proteins, enzymes, and muscle tissue. Tyrosine helps produce neurotransmitters, including epinephrine, norepinephrine, and dopamine, that affect mood, memory, and alertness.

Tyrosine is also involved in the production of melanin, the pigment that gives color to skin and hair, and thyroid hormones, which help regulate metabolism.

Tyrosine is found in many foods, including eggs, cheese, soybeans, chicken, beef, pork, fish, nuts, and beans. It's also available as a dietary supplement, commonly used to boost attention and focus.

Potential Benefits of Tyrosine

Tyrosine supplements may be helpful for certain people, especially those with a hereditary condition called phenylketonuria. Research shows that taking tyrosine supplements may also help improve cognitive function, particularly under periods of stress.

May Help People With Phenylketonuria

Phenylketonuria (PKU) is a rare but serious genetic disorder usually detected at birth. It's characterized by low levels of phenylalanine hydroxylase (PAH), an enzyme that breaks down the amino acid phenylalanine. This causes phenylalanine to build up in the blood, leading to brain damage and intellectual disability.

Tyrosine is made from phenylalanine, so people with PKU typically have low levels of tyrosine in their blood. This can affect behavior, mood, and thinking.

The treatment for PKU is to follow a diet low in phenylalanine. Supplementing with low-phenylalanine or phenylalanine-free amino acid supplements with tyrosine is recommended. However, there is currently not enough evidence to support taking an additional tyrosine supplement to improve health outcomes.

One review included three trials with 56 people who had PKU. Despite higher blood levels of tyrosine with routine supplementation, the study found no differences in neuropsychological performance compared to a placebo (no treatment).

Improves Cognitive Function Under Stress

Stressful situations can quickly reduce catecholamine neurotransmitters, including norepinephrine and epinephrine (adrenaline), that help with cognitive function. This can negatively affect decision-making and working memory.

There is some evidence that tyrosine, as a precursor to catecholamines, may prevent catecholamine depletion and improve cognitive performance during periods of extreme stress.

A review of 15 studies found that increased tyrosine intake may counteract the decline in cognitive function and behavior caused by physically or mentally stressful situations. Cognitive improvements, including working memory and information processing, were seen after a single dose.

A randomized controlled trial of 80 people examined the effect of tyrosine on stress markers and cognitive performance following a virtual reality (VR) active shooter training drill. Researchers found that, despite not lowering stress markers, tyrosine led to improvements in cognitive performance. In particular, it resulted in fewer missed answers on a test that measured response time and decision accuracy.

No significant evidence shows improvement in brain function during periods of mild stress or while resting.

May Improve Mood Under Stress

Behavioral changes, such as improved mood, may result from consistent tyrosine supplementation during stressful situations.

One study conducted in Antarctica over two seasons found that people who regularly took tyrosine during the arctic winter showed a 47% increase in mood scores compared to a 136% decrease in the placebo group. No significant changes in mood were observed during the summer.

Additional research is needed to confirm the effects of tyrosine supplementation on improving mood.

Other Potential Benefits

There is interest in using tyrosine supplements for other purposes, including boosting athletic performance and treating depression, chronic fatigue, and attention-deficit hyperactivity disorder (ADHD). However, current evidence does not support its effectiveness for these purposes.

How Much Do You Need?

For most adults, the current estimated daily requirement for phenylalanine and tyrosine combined is 27 milligrams per kilogram (mg/kg) of body weight. This requirement increases to 33 mg/kg for children with PKU and 36 mg/kg for pregnant people. However, data suggests that even these increased amounts may not be sufficient during pregnancy.

Protein synthesis is optimized with a 60:40 phenylalanine to tyrosine ratio, which means adults should ideally consume around 10.8 milligrams of tyrosine for each kg of body weight, or 4.9 milligrams per pound (mg/lb).

Most people get enough tyrosine from their diet and don't need supplementation.

The dosage of tyrosine supplements given in studies greatly varies, ranging from fixed amounts of 2-20 g to 25-150 mg/kg of body weight.

Speak with a healthcare provider to discuss the most appropriate dose for your health concerns.

Good Sources of Tyrosine

Many foods contain tyrosine, making it relatively easy to meet the daily requirements. Meat and meat products are among the best dietary sources. For example, each 6-ounce (oz) cooked serving of chicken and steak provides 1,446 mg and 1,640 mg of tyrosine, respectively.

Other dietary sources of tyrosine include:

• Soybeans and other beans
• Beef, lamb, pork
• Chicken
• Fish
• Sesame seeds
  
• Avocado
  
• Nuts
• Eggs
• Dairy, including cheese
  
• Whole grains

Supplements

Tyrosine is commonly added to energy drinks and pre-workout supplements to help boost focus and decrease fatigue. However, little research currently supports its effectiveness in improving athletic performance.

Tyrosine is also sold in its free form as capsules or tablets. If you decide to try a tyrosine supplement, choose one that a third party has tested, as the U.S. Food and Drug Administration (FDA) does not regulate dietary supplements.

Potential Risks and Side Effects

Tyrosine is generally recognized as safe (GRAS) in supplement form. Research has used doses of up to 150 mg/kg of body weight for up to three months with no significant side effects. There are no known side effects of long-term use, but more research is needed.

People with hyperthyroidism (overactive thyroid) should consult with a healthcare provider before taking tyrosine supplements because it may increase thyroid hormone levels.

Tyrosine Deficiency

Tyrosine deficiency is rare among healthy individuals. People with PKU are at a greater risk of low tyrosine levels, which has been associated with cognitive dysfunction, light skin and hair due to decreased melanin synthesis, and ADHD in this population.

Medication Interactions

Tyrosine-rich foods and supplements may interact with monoamine oxidase inhibitors (MAOIs), a class of antidepressant medications, causing a rapid increase in blood pressure. This dangerous increase in blood pressure, known as a hypertensive crisis, can lead to headaches, blurred vision, and chest pain. In severe cases, it can lead to a heart attack or stroke.

Examples of MAOIs include:

• Marplan (isocarboxazid)
• Nardil (phenelzine)
• Parnate (tranylcypromine)

If a person with Parkinson's disease (PD) takes tyrosine before the medication levodopa, tyrosine may compete in the gut for absorption, making it harder to absorb levodopa. Taking tyrosine two hours before or after levodopa may prevent this interaction.

A Quick Review

Tyrosine is a non-essential amino acid that the body naturally produces from another amino acid called phenylalanine. It helps make the pigment melanin and thyroid hormones. Tyrosine also helps make catecholamine neurotransmitters, which play an important role in the body's stress response.

Research shows that tyrosine supplementation can help replenish neurotransmitters that become depleted during stressful conditions, which may help boost cognitive function and mood. However, the effectiveness of tyrosine supplementation in healthy individuals under mild to moderate stress is inconclusive, and additional research is needed.

Tyrosine supplements are generally not needed because it's found in many foods, including meat, eggs, chicken, and fish. People with a rare genetic condition called PKU are among those at the greatest risk of deficiency.

Tyrosine is generally considered safe. However, as with all supplements, it's essential to consult a healthcare provider to determine whether the potential benefits outweigh the risks.