L-Tyrosine is an amino acid produced within the body from a variety of dietary sources. Its primary roles are protein synthesis and maintaining healthy brain chemistry by providing the material from which dopamine, epinephrine, and norepinephrine are produced. These three vital neurotransmitters, known as catecholamines, have a profound effect on energy levels, mood, motivation, and cognitive function.

Though L-tyrosine doesn’t directly stimulate the production of these neurotransmitters, it does provide a “buffer” of the raw material the brain needs to produce them, particularly beneficial when stress has depleted their levels. L-Tyrosine also helps regulate the production of certain hormones and is necessary for the creation of the pigment melanin, which is present in skin, hair, and eyes. In addition, L-tyrosine is chemically related to thyroid hormones and may enhance weight loss by suppressing appetite and improving the body’s ability to burn fat.

Because the body can produce adequate amounts of L-tyrosine, supplementation isn’t essential for basic health. However, studies suggest that taking additional L-tyrosine can have both physical and cognitive benefits, particularly in scenarios that involve physical or environmental stressors.

Benefits and Effects

There is robust evidence for the effectiveness of L-tyrosine supplementation, particularly regarding cognitive enhancement, mood and motivation improvement, and mitigating the effects of stress on the mind. Some of the most commonly attributed benefits of L-tyrosine include the following:

Cognitive Enhancement Under Stress

A 2015 review of more than a dozen studies found that tyrosine loading effectively offset working memory and information processing deficits created by environmental stressors such as extreme weather or extreme cognitive demand.‍[1] The review speculated that this effect might be explained by the fact that tyrosine provides a “buffer” of raw material from which the brain can produce neurotransmitters, effectively neutralizing the depletion that stress creates. The review concluded that there is evidence that healthy individuals exposed to demanding situational conditions may benefit from supplemental L-tyrosine.

A 1999 military study of cadets on a combat training course showed that a week of L-Tyrosine supplementation significantly lowered systolic blood pressure.‍[2] The participants receiving L-tyrosine also performed better on memory and tracking tasks than those receiving a placebo.

Sleep-deprived individuals receiving supplemental L-tyrosine performed significantly better at a variety of cognitive and psychomotor tasks than a similar group which was given placebo in a 1995 study.‍[3]

Working Memory Improvement Under Increased Cognitive Demand

A 2013 study investigating the effect of L-tyrosine on adults doing a progressively challenging mental task found that participants who took supplemental tyrosine did better on the more difficult levels of the task but showed little or no improvement on the easier levels.‍[4] The researchers said the results confirm the concept that L-tyrosine selectively targets cognitive control situations, providing more resources only when more control is needed.

Increased Cognitive Flexibility

A small 2015 study involving 22 healthy adults showed that supplemental L-tyrosine enhanced cognitive flexibility, the ability to switch between tasks or modalities of thought.‍[5] This result was attributed largely to the fact that L-tyrosine increases brain levels of dopamine, which is believed to control cognitive flexibility.

ADHD Treatment and Focus Enhancement

A 2011 study of both adult and pediatric ADHD patients showed that 77% of patients treated with L-tyrosine alone showed significant improvement over a period of 10 weeks. Further studies indicated that the positive effect of pharmaceutical ADHD medication was markedly enhanced by the simultaneous administration of L-tyrosine.‍[6]

Anecdotally, even individuals without ADHD report enhanced focus from L-tyrosine supplementation.

How It Works

L-Tyrosine is created within the body from a variety of high protein dietary sources, including lean beef, pork, poultry, fish, nuts, soy products, milk, yogurt, cottage cheese, and some hard cheeses. It is produced when a precursor amino acid called phenylalanine is metabolized in the liver.

When phenylalanine has been converted to L-tyrosine, it is further metabolized by an enzyme called tyrosine hydroxylase, which prepares L-tyrosine to be used for the creation of catecholamine neurotransmitters. After it is hydrolyzed by the enzyme, L-tyrosine is carried in plasma and can be metabolized into catecholamines in various tissues.

The release of the tyrosine hydroxylase enzyme is activated by stimulation of adrenergic neurons in the brain, creating an internal regulatory system that maintains adequate catecholamine levels when the body is experiencing stress. When there is a high demand on the body’s stores of epinephrine, norepinephrine, or dopamine, the brain responds with an increased release of adrenergic transmitters. This, in turn, increases the amount of the modifying enzyme released, and more L-tyrosine can be converted into catecholamines, boosting levels and preventing deficits.

This regulatory system is believed by many to be an argument in favor of L-tyrosine supplementation. When the release of the tyrosine hydroxylase enzyme is increased over a sustained period of time, catecholamine synthesis is thought to become dependent on concentrations of tyrosine, and supplementation may increase catecholamine synthesis and release by ensuring a sufficiency of tyrosine during prolonged periods of stimulation.


Tyrosine supplements are available in two forms, standard L-tyrosine and NALT (N-Acetyl-L-Tyrosine), a modified form of L-tyrosine that has an acetyl group attached to the tyrosine molecule to enhance bioavailability. The acetylated form of the supplement is more soluble than the standard form and is broken down in the kidneys, where it becomes L-tyrosine. Both forms of the supplement provide the same functions and benefits. However, NALT may be more effective in a nootropic stack due to its improved bioavailability.

The standard recommended dosage of L-tyrosine for a healthy adult is 500-1000 mg daily, divided into two to three doses and taken 30 minutes before meals. Higher daily dosages can trigger a variety of side effects, and daily dosages of 12 grams or more can lead to toxicity.

The recommended dose for NALT is lower, with 300 mg being a standard daily dose for cognitive enhancement purposes.


N-Acetyl-L-Tyrosine Stack for Universal Cognitive Enhancement

For a preformulated nootropic that contains a blend of 11 cognitive enhancing supplements, including NALT, designed to optimize a wide array of cognitive functions, we recommend Mind Lab Pro.

Mind Lab Pro’s strategy aims at all aspects of memory, mental performance, mood and stress resistance, and brain repair, and maintenance. Their combination of nootropics is designed to affect brain energy, neurotransmitters, brain blood flow, brain waves, neuroprotection, and regeneration.

Read our Mind Lab Pro review for a detailed overview.

Side Effects

L-tyrosine is considered safe when taken in recommended doses. Commonly reported side effects tend to be both mild and temporary, and include headaches, migraine, indigestion, stomach trouble and gastrointestinal upset.

Contraindications: L-Tyrosine should not be taken by people who are taking high blood pressure medication, Levadopa, thyroid medication, MAO inhibitors, or stimulants. L-tyrosine should not be taken by individuals with thyroid disease, Graves disease, or melanoma. L-tyrosine has not been proven safe for women who are pregnant or nursing.

Where to Buy

L-Tyrosine is readily available in retail stores that sell supplements as well as via online vendors.

We recommend buying L-tyrosine from, a one-stop shop for cognitive enhancing supplements.

If you prefer to do your shopping on, we recommend Source Naturals N-Acetyl L-Tyrosine Capsules as a high-quality source of L-tyrosine.

Alternatively, if you’d like to take a supplement that contains a blend of 11 cognitive enhancing nootropics, including NALT, we recommend Mind Lab Pro. Read our Mind Lab Pro review for a detailed overview.

Closing Thoughts

L-Tyrosine is a tested and proven supplement with evidence that it can enhance memory, increase cognitive flexibility, and improve mental performance in individuals exposed to acute stress or elevated cognitive demand.

One of the most interesting aspects of L-tyrosine supplementation is that it definitely performs best under pressure. Does this mean that L-tyrosine’s effectiveness to only extreme situations?

While there is limited research on this aspect of L-tyrosine, the few studies that have been done, combined with anecdotal evidence from users, indicate that L-tyrosine may well be beneficial even for those that are not experiencing military-grade stress.

Working or studying long hours, struggling with anxiety, and even intense exercise are all stressors, that can have a negative effect on cognition, and L-tyrosine supplementation may help.

References   [ + ]

Planning to start a new supplementation regimen? See our medical disclaimer.

This page was last updated on November 6, 2018.