Tyrosine, also known as L-tyrosine, is a non-essential amino acid that your body can synthesize from phenylalanine. It plays a critical role in the creation of proteins, enzymes, muscle tissue, and neurotransmitters like dopamine, norepinephrine, and epinephrine. These neurotransmitters influence mood, alertness, and memory.

Tyrosine is also important in producing melanin—the pigment responsible for skin and hair color—and thyroid hormones that regulate metabolism. This amino acid is found in a wide range of foods, including eggs, meats, soy products, dairy, and legumes. It is also available in supplement form, often marketed to support focus and mental performance.

Potential Benefits of Tyrosine

May Help People With Phenylketonuria (PKU)

Phenylketonuria (PKU) is a rare genetic disorder characterized by a deficiency in the enzyme phenylalanine hydroxylase (PAH), leading to a buildup of phenylalanine in the body. Since tyrosine is synthesized from phenylalanine, people with PKU often have low levels of tyrosine, which may affect brain function and behavior.

While supplementation with tyrosine is common in PKU diets, current research does not show clear evidence that additional tyrosine supplements improve neuropsychological outcomes. A review of three trials found no significant improvements in cognitive performance despite increased tyrosine levels.

Improves Cognitive Function Under Stress

During stress, levels of neurotransmitters like norepinephrine and dopamine may decrease, impairing decision-making and mental clarity. Tyrosine supplementation has shown promise in replenishing these neurotransmitters and preserving cognitive performance under extreme stress.

A review of 15 studies found improvements in working memory and decision-making following tyrosine supplementation during stressful conditions. One study even showed better test performance in participants undergoing a simulated high-stress VR training exercise.

May Improve Mood Under Stress

Preliminary research suggests that tyrosine may help stabilize mood during stress. In an Antarctic study, those who supplemented with tyrosine showed a 47% improvement in mood scores compared to a significant drop in the placebo group. However, the effect was only observed during winter conditions, not in summer.

More evidence is needed to fully understand tyrosine’s impact on mood regulation.

Other Potential Uses

Tyrosine is being explored for its potential to support athletic performance and address conditions like depression, chronic fatigue, and ADHD. However, there is currently limited scientific backing for these uses.

How Much Tyrosine Do You Need?

The daily requirement for phenylalanine and tyrosine combined is about 27 mg/kg of body weight for adults. For children with PKU and pregnant people, this requirement is slightly higher—33 mg/kg and 36 mg/kg, respectively.

For optimal protein synthesis, a 60:40 ratio of phenylalanine to tyrosine is ideal. This means adults should aim for approximately 10.8 mg/kg of tyrosine daily. Most people meet this requirement through a balanced diet without the need for supplements.

Supplement dosages in studies range from 2–20 grams per day or 25–150 mg/kg of body weight, depending on the objective. Always consult a healthcare provider before using tyrosine supplements.

Good Sources of Tyrosine

You can obtain tyrosine from both animal and plant-based foods. Some of the best sources include:

  • Chicken and beef (6 oz cooked = ~1,500 mg)

  • Soy products (tofu, soybeans)

  • Pork, lamb, fish

  • Eggs and dairy products (especially cheese)

  • Nuts and seeds (like sesame)

  • Beans and legumes

  • Avocados

  • Whole grains

Tyrosine is also added to energy drinks and workout supplements, although there’s little evidence supporting improved athletic outcomes.

Potential Risks and Side Effects

Tyrosine supplements are generally recognized as safe (GRAS) and have been tested in doses of up to 150 mg/kg body weight without major side effects for up to three months. However, individuals with hyperthyroidism should avoid taking tyrosine without medical advice, as it may elevate thyroid hormone levels.

Long-term safety data is still lacking, so consult a healthcare provider before starting.

Tyrosine Deficiency

Tyrosine deficiency is rare, especially in people without PKU. However, individuals with PKU may experience low tyrosine levels, leading to cognitive issues, reduced melanin production (light skin/hair), and ADHD-like symptoms.

Medication Interactions

Tyrosine can interact with monoamine oxidase inhibitors (MAOIs)—a class of antidepressants. This interaction may cause a hypertensive crisis, marked by dangerously high blood pressure, headaches, and chest pain. It can even result in a stroke or heart attack.

Examples of MAOIs include:

  • Marplan (isocarboxazid)

  • Nardil (phenelzine)

  • Parnate (tranylcypromine)

Tyrosine may also interfere with levodopa (a Parkinson's medication), affecting absorption. To avoid interaction, take tyrosine at least two hours apart from levodopa.

A Quick Review

Tyrosine is a non-essential amino acid that supports neurotransmitter production, skin pigmentation, and thyroid function. Supplementing with tyrosine may help boost cognitive function and mood under stress, but evidence is limited for mild stress or other conditions like ADHD.

Most people get enough tyrosine through food sources, so supplementation is typically unnecessary unless recommended by a healthcare provider. While generally safe, tyrosine supplements should be used cautiously, especially if you are on medication or have thyroid issues.