L-tyrosine can boost your cognition, mood, and thyroid hormones, especially when you’re under stress. However, it may do the opposite and worsen mental health in some cases. Read on to discover both sides of L-tyrosine supplements and learn how to use them properly.

What is L-Tyrosine?

The “Cheese” Amino Acid

L-tyrosine is a naturally occurring form of tyrosine, an amino acid your body uses to make proteins, neurotransmitters, and other vital compounds [1].

We don’t depend on food sources of tyrosine since we can make it from another amino acid, phenylalanine; this makes tyrosine a non-essential amino acid. Still, you can ensure its optimal levels by eating a variety of tyrosine-rich foods such as [2, 3]:

  • Cheese and dairy
  • Turkey
  • Beans
  • Eggs
  • Chicken
  • Peanuts

Did you know? Scientists named tyrosine after cheese (Greek: tyros), where they discovered it.

L-tyrosine is a popular nootropic supplement; people use it to boost cognition and alertness under stress. You will find it alone or combined with other ingredients in protein and pre-workout supplements.

L-tyrosine is an amino acid your body uses to make proteins and other vital compounds. People take it as a supplement to enhance cognition and mental clarity.



  • Boosts cognition under stress
  • Helps with mood disorders
  • May improve attention
  • May boost thyroid hormones
  • Helps with fibromyalgia


  • May cause headache and anxiety
  • May worsen cognition in the elderly
  • Interacts with L-DOPA and thyroid medications

Roles and Functions

Source: https://commons.wikimedia.org/wiki/File:Conversion_of_phenylalanine_and_tyrosine_to_its_biologically_important_derivatives.png

In your body, tyrosine acts as a precursor to neurotransmitters called catecholamines [4]:

These components play central roles in your mental health, cognition, behavior, and stress response. They also control your blood pressure and metabolism [5, 6].

As a supplement, L-tyrosine may be beneficial under stressful conditions that deplete your catecholamines.

Tyrosine helps build thyroid hormones and the skin pigment melanin [7, 8].

Your brain uses L-tyrosine to make dopamine and other neurotransmitters. Supplementing may help prevent drops in these neurotransmitters when you’re under stress.

N-Acetyl-L-Tyrosine (NALT)

N-acetyl-L-tyrosine (NALT or NAT) is more water-soluble than L-tyrosine and thus more suitable for intravenous nutrition for people who can’t eat and drink [9].

As a nutritional supplement, our bodies supposedly use it better than L-tyrosine, but the evidence tells a different story. We metabolize only 25% of NALT into free tyrosine and eliminate 35-38% with the urine [9, 10, 11].

In a study of 13 subjects, N-acetyl-L-tyrosine didnt increase tyrosine levels at all [12].

Thus, L-tyrosine remains a better option for oral supplementation.

N-acetyl-L-tyrosine is more soluble than L-tyrosine, but your body can’t use it as well. You may want to stick with L-tyrosine in supplements.

L-Tyrosine Benefits

1) Boosts Cognition Under Stress

A review of 15 clinical trials investigated the effects of L-tyrosine loading – short bouts of higher doses – on cognition and behavior. This dosing pattern prevented catecholamine depletion and boosted mental function in stressful and demanding situations [13].

It showed the best results in people exposed to:

  • Multitasking and distractions [14, 15, 16]
  • Sleep deprivation [17, 18]
  • Harsh military training [19, 20]
  • Cold weather [21, 22, 23]

Some people use L-tyrosine to enhance their physical performance under stress. However, multiple reviews failed to confirm this effect [13, 24, 25, 26].

Additionally, L-tyrosine may not improve cognitive performance under normal conditions. In older adults, L-tyrosine loading even produced the opposite effects – worsening memory and cognitive function [27].

L-tyrosine may boost your cognition in stressful situations such as multitasking, sleep deprivation, and cold exposure. It has no impact on physical performance.

2) Helps With Mood Disorders

Imbalances in brain neurotransmitters can lead to depression and other mood disorders. Since tyrosine enables the production of dopamine and noradrenaline, it may act as nutritional mood support [28].

Some doctors have reported success with L-tyrosine for a couple of patients with depression [29].

It seems to be beneficial for particular mood disorders such as:

  • Depression due to low dopamine [30]
  • Low mood from living in harsh, cold environments [31, 32]
  • Depression after childbirth [33]

However, the above results stem from small clinical trials, some of which lacked placebo controls. A larger trial of 65 patients failed to verify the antidepressant effects of L-tyrosine [34].

It induced no changes in mood or behavior in healthy people under normal conditions [35, 36].

L-tyrosine may relieve the winter blues and certain types of depression, but the evidence is limited.

3) May Boost Thyroid Hormones

With the help of selenium, your body combines tyrosine and iodine to make thyroid hormones [7].

In 85 volunteers, supplementation with high doses of L-tyrosine (12 g daily) during harsh winter slightly increased T3, the active thyroid hormone. It also greatly reduced TSH, high levels of which are linked with hypothyroidism and stress [32].

Tyrosine supplementation prevented thyroid hormone drops in mice exposed to chronic stress [37].

Large, well-designed clinical trials should confirm the benefits of L-tyrosine supplementation for thyroid health.

Tyrosine builds thyroid hormones, but the benefits of supplementation for thyroid health lack solid evidence.

4) May Help With Attention Disorders

In a clinical trial, L-tyrosine improved attention in eight of 12 participants with attention deficit disorder over two weeks. However, after six weeks, all patients developed a tolerance to the treatment, and their improvement stalled [38].

L-tyrosine supplementation provided no benefits to 7 children with ADHD [39].

Impaired production of dopamine and noradrenaline may trigger attention disorders, and such cases would more likely benefit from tyrosine supplementation [40].

Combination With Adderall

Adderall is an amphetamine-based drug for attention disorders; its long-term use may deplete brain catecholamines [41, 42].

L-tyrosine helps restore catecholamines, and some people combine it with Adderall to lessen the side effects. No studies have verified the safety and efficacy of this combination.

There’s not enough evidence to proclaim L-tyrosine effective for attention disorders, neither alone nor in combination with Adderall.

5) Combats Narcolepsy

Patients with narcolepsy struggle to stay awake during the day. They often experience cataplexy (sudden muscle weakness with intact awareness) and sleep paralysis [43].

L-tyrosine supplies dopamine and noradrenaline, neurotransmitters that promote arousal and prevent cataplexy [44, 4].

In a study of 10 patients, L-tyrosine improved only three of more than 20 tested symptoms. The patients felt less tired and more alert [45].

A group of doctors managed to handle daytime sleep attacks and cataplexy with L-tyrosine in eight patients. They kept using this approach in other narcolepsy patients after the initial success. The lack of placebo controls doesn’t allow for a definite conclusion [46].

According to limited clinical evidence, L-tyrosine may reduce daytime bouts of sleep and muscle weakness in people with narcolepsy.

6) May Relieve Addiction and Substance Withdrawal

Dopamine plays a central role in the brain’s reward pathway. Scientists first thought that it makes certain things (such as food and sex) enjoyable. New research suggests dopamine actually doesn’t make us feel pleasure, it makes us want it. People with addiction may be depleting or over-sensitizing this pathway, which increases their cravings and drug-seeking behavior [47].

In 83 former heroin addicts, a combination of L-tyrosine and other neurotransmitter precursors (lecithin, L-glutamine, and 5-HTP) significantly improved withdrawal symptoms such as [48]:

  • Anxiety
  • Depression
  • Anger and hostility
  • Fatigue
  • Suppressed vigor
L-tyrosine may relieve addiction and substance withdrawal, but the available research is scarce.

Weight Loss

Tyrosine supplies catecholamines and thyroid hormones, which both enhance metabolism and energy production. For this reason, many people want to know if L-tyrosine can boost weight loss.

A supplement containing L-tyrosine, green tea extract, and caffeine slightly enhanced weight loss in 80 obese adults. Other ingredients have likely contributed to the results [49].

No other trials have documented the benefits of L-tyrosine for weight loss.

Based on the current evidence, we can’t tell if L-tyrosine supports weight loss.


People with an inborn metabolic disorder – phenylketonuria (PKU) – are unable to break down phenylalanine properly. In turn, the buildup of phenylalanine causes brain damage and cognitive impairment [50, 51, 52].

These patients should follow a special low-protein diet to minimize the intake of phenylalanine. They are at risk of tyrosine deficiency since the body converts phenylalanine into tyrosine.

L-tyrosine supplementation for PKU may sound reasonable, but a Cochrane Database review of six clinical trials failed to confirm its benefits [53].

To avoid variations in blood tyrosine levels, doctors suggest using protein substitutes with optimized tyrosine content (3-6g/100g) instead [54, 55, 56, 57].

Patients with phenylketonuria lack tyrosine, but they may not benefit from L-tyrosine supplementation.

L-Tyrosine Side Effects and Precautions

Side Effects

According to the FDA, L-tyrosine is “generally recognized as safe” (GRAS) [58].

It was safe in clinical trials and caused only minor side effects such as [13, 24]:

  • Headache
  • Irritability
  • Nausea

High doses (100-200 mg/kg) caused cognitive decline in older adults [27].

Drug Interactions

L-tyrosine competes for brain uptake with L-DOPA, a drug for Parkinson’s disease. Tyrosine supplements and even tyrosine-rich foods may hinder the transport of L-DOPA into the brain; this can lead to variations in the treatment response, known as the “on-off” phenomenon [59, 60].

This interaction is crucial since many people use L-tyrosine as a natural dopamine booster for Parkinson’s disease, despite the lack of clinical evidence [61, 62].

Patients with Parkinson’s disease are often deficient in tyrosine hydroxylase – an enzyme that converts tyrosine to L-DOPA – which is another limitation for tyrosine supplements [63].

High doses of L-tyrosine (12 g daily, for 4 months) can increase thyroid hormones. People with an overactive thyroid and those taking thyroid medications may want to avoid it [32].

L-tyrosine supplements may interact with thyroid medications and L-DOPA treatment for Parkinson’s disease.

Sensitive Groups

Children and pregnant women should avoid L-tyrosine unless prescribed by their doctor. This supplement is safe for nursing women as it doesn’t increase the milk tyrosine content [64, 65, 33].

L-Tyrosine Dosage & Supplements


Average L-tyrosine dosage for most conditions is 100 mg/kg; that would be around 7 g daily for a 154-lbs (70-kg) person, divided into 2-3 daily doses. It’s a good idea to start with a lower dose and work your way up to an optimal response [13, 24].

For short-term cognitive enhancement, you should take L-tyrosine 30-60 mins before a stressful or challenging task. Benefits for depression, fibromyalgia, and attention disorders usually take 1-4 weeks [13, 30, 45, 38].

Supplement Reviews

Most products contain 500 mg of L-tyrosine per pill. If you need long-term supplementation with higher doses, bulk powders might be a better option.

Users take L-tyrosine to boost their mental clarity, alertness, and focus. A smaller number has reported success with depression, sugar cravings, and alcohol withdrawal.

Combinations with antidepressants and other supplements such as 5-HTP are popular for mood disorders, but you should never combine drugs and supplements before consulting with your doctor.

Other users experienced no benefits for cognition and mental health; some of them even said their mood and focus worsened. The most common side effects are anxiety, headache, and insomnia. Users also suggest starting with lower doses to see how your body will react.

People take L-tyrosine (500 mg per pill) to boost mood and cognition. Start with lower doses to avoid headache, anxiety, and insomnia and consult with your doctor first.


Want More Targeted Ways to Enhance Brain Function and Mood?

If you’re interested in natural and targeted ways of improving your cognitive function, we recommend checking out SelfDecode’s Limitless Mind DNA Protocol. It gives genetic-based diet, lifestyle and supplement tips that can help improve your cognitive function. The recommendations are personalized based on your genes.

Also check out SelfDecode’s Mood DNA Wellness Report. It also gives genetic-based diet, lifestyle and supplement tips that can help improve your mood.

SelfDecode is a sister company of SelfHacked. This post contains sponsored links, which means that we may receive a small percentage of profit from your purchase, while the price remains the same to you. The proceeds from your purchase support our research and work. Thank you for your support.


L-tyrosine is an amino acid that builds proteins, neurotransmitters, and thyroid hormones in your body. Protein-rich foods such as cheese, meat, eggs, and beans are great sources of this amino acid.

Supplementation with L-tyrosine boosts your cognitive performance when you’re under stress. It may also improve mood and attention and help with substance dependence.

L-tyrosine may cause headache, anxiety, and nausea. Pregnant women, children, and people taking L-DOPA or thyroid hormones should avoid it unless prescribed by a doctor.

About the Author

Aleksa Ristic, MSc (Pharmacy)

MS (Pharmacy)

Aleksa received his MS in Pharmacy from the University of Belgrade, his master thesis focusing on protein sources in plant-based diets.


Aleksa is passionate about herbal pharmacy, nutrition, and functional medicine. He found a way to merge his two biggest passions—writing and health—and use them for noble purposes. His mission is to bridge the gap between science and everyday life, helping readers improve their health and feel better.

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