Tyrosine: Benefits, Side Effects and Dosage

Tyrosine is an amino acid that is naturally produced in the body from another amino acid called phenylalanine.

It’s found in many foods, especially in cheese, where it was first discovered. In fact, “tyros” means “cheese” in Greek (2Trusted Source).

It is also found in chicken, turkey, fish, dairy products and most other high-protein foods (3Trusted Source).

Tyrosine helps make several important substances, including (4):

• Dopamine: Dopamine regulates your reward and pleasure centers. This important
  brain chemical is also important for memory and motor skills (5Trusted Source).
• Adrenaline
  and noradrenaline: These hormones are responsible
  for the fight-or-flight response to stressful situations. They prepare the
  body to “fight” or “flee” from a perceived attack or harm (5Trusted Source).
• Thyroid
  hormones: Thyroid hormones are produced by the thyroid
  gland and primarily responsible for regulating metabolism (6Trusted Source).
• Melanin: This pigment gives your skin, hair and eyes their color.
  Dark-skinned people have more melanin in their skin than light-skinned
  people (7Trusted Source).

It’s also available as a dietary supplement. You can purchase it alone or blended with other ingredients, such as in a pre-workout supplement.

Supplementing with tyrosine is thought to increase levels of the neurotransmitters dopamine, adrenaline and norepinephrine.

By increasing these neurotransmitters, it may help improve memory and performance in stressful situations (4).

Summary Tyrosine is an amino
acid that the body produces from phenylalanine. Supplementing with it is
thought to increase important brain chemicals, which affect your mood and
stress response.

Stress is something that everyone experiences.

This stress can negatively affect your reasoning, memory, attention and knowledge by decreasing neurotransmitters (8Trusted Source, 9Trusted Source).

For example, rodents who were exposed to cold (an environmental stressor) had impaired memory due to a decline in neurotransmitters (10, 11Trusted Source).

However, when these rodents were given a tyrosine supplement, the decline in neurotransmitters was reversed and their memory was restored.

While rodent data does not necessarily translate to humans, human studies have found similar results.

In one study in 22 women, tyrosine significantly improved working memory during a mentally demanding task, compared to a placebo. Working memory plays an important role in concentration and following instructions (12Trusted Source).

In a similar study, 22 participants were given either a tyrosine supplement or placebo before completing a test used to measure cognitive flexibility. Compared to the placebo, tyrosine was found to improve cognitive flexibility (13Trusted Source).

Cognitive flexibility is the ability to switch between tasks or thoughts. The quicker a person can switch tasks, the greater their cognitive flexibility.

Additionally, supplementing with tyrosine has been shown to benefit those who are sleep deprived. A single dose of it helped people who lost a night’s sleep stay alert for three hours longer than they otherwise would (14Trusted Source).

What’s more, two reviews concluded that supplementing with tyrosine can reverse mental decline and improve cognition in short-term, stressful or mentally demanding situations (15, 16Trusted Source).

And while tyrosine may provide cognitive benefits, no evidence has suggested that it enhances physical performance in humans (16Trusted Source, 17Trusted Source, 18Trusted Source).

Lastly, no research suggests that supplementing with tyrosine in the absence of a stressor can improve mental performance. In other words, it won’t increase your brainpower.

Summary Studies show that
tyrosine can help maintain your mental capacity when taken before a stressful
activity. However, there is no evidence that supplementing with it can improve your memory.

Phenylketonuria (PKU) is a rare genetic condition caused by a defect in the gene that helps create the enzyme phenylalanine hydroxylase (19Trusted Source).

Your body uses this enzyme to convert phenylalanine into tyrosine, which is used to create neurotransmitters (4).

However, without this enzyme, your body cannot break down phenylalanine, causing it to build up in the body.

The primary way to treat PKU is to follow a special diet that limits foods containing phenylalanine (20Trusted Source).

However, because tyrosine is made from phenylalanine, people with PKU can become deficient in tyrosine, which can contribute to behavioral problems (21Trusted Source).

Supplementing with tyrosine may be a viable option for alleviating these symptoms, but the evidence is mixed.

In one review, researchers investigated the effects of tyrosine supplementation alongside or in place of a phenylalanine-restricted diet on intelligence, growth, nutritional status, mortality rates and quality of life (22Trusted Source).

The researchers analyzed two studies including 47 people but found no difference between supplementing with tyrosine and a placebo.

A review of three studies including 56 people also found no significant differences between supplementing with tyrosine and a placebo on the outcomes measured (23Trusted Source).

The researchers concluded that no recommendations could be made about whether tyrosine supplements are effective for the treatment of PKU.

Summary PKU is a serious
condition that may cause tyrosine deficiency. More studies are needed before
recommendations can be made about treating it with tyrosine supplements.

Tyrosine has also been said to help with depression.

Depression is thought to occur when the neurotransmitters in your brain become unbalanced. Antidepressants are commonly prescribed to help realign and balance them (24Trusted Source).

Because tyrosine can increase the production of neurotransmitters, it’s claimed to act as an antidepressant (25Trusted Source).

However, early research doesn’t support this claim.

In one study, 65 people with depression received either 100 mg/kg of tyrosine, 2.5 mg/kg of a common antidepressant or a placebo each day for four weeks. Tyrosine was found to have no antidepressant effects (26Trusted Source).

Depression is a complex and varied disorder. This is likely why a food supplement like tyrosine is ineffective at combating its symptoms.

Nevertheless, depressed individuals with low levels of dopamine, adrenaline or noradrenaline may benefit from supplementing with tyrosine.

In fact, one study among individuals with dopamine-deficient depression noted that tyrosine provided clinically significant benefits (27Trusted Source).

Dopamine-dependent depression is characterized by low energy and a lack of motivation (27Trusted Source).

Until more research is available, the current evidence does not support supplementing with tyrosine to treat symptoms of depression (25Trusted Source).

Summary Tyrosine can be
converted into neurotransmitters that affect mood. However, research doesn’t
support supplementing with it to combat symptoms of depression.

Tyrosine is “generally recognized as safe” (GRAS) by the Food and Drug Administration (28).

It has been supplemented safely at a dose of 68 mg per pound (150 mg per kg) of body weight per day for up to three months (15, 29Trusted Source, 30Trusted Source).

While tyrosine is safe for most people, it can cause side effects and interact with medications.

Monoamine Oxidase Inhibitors (MAOIs)

Tyramine is an amino acid that helps regulate blood pressure and is produced by the breakdown of tyrosine.

Tyramine accumulates in foods when tyrosine and phenylalanine are converted to tyramine by an enzyme in microorganisms (31).

Cheeses like cheddar and blue cheese, cured or smoked meats, soy products and beer contain high levels of tyramine (31).

Antidepressant medications known as monoamine oxidase inhibitors (MAOIs) block the enzyme monoamine oxidase, which breaks down excess tyramine in the body (2Trusted Source, 32Trusted Source, 33Trusted Source).

Combining MAOIs with high-tyramine foods can increase blood pressure to a dangerous level.

However, it is unknown if supplementing with tyrosine may lead to a buildup of tyramine in the body, so caution is necessary for those taking MAOIs (34Trusted Source, 35).

Thyroid Hormone

The thyroid hormones triiodothyronine (T3) and thyroxine (T4) help regulate growth and metabolism in the body.

It’s important that T3 and T4 levels are neither too high nor too low.

Supplementing with tyrosine may influence these hormones (36Trusted Source).

This is because tyrosine is a building block for the thyroid hormones, so supplementing with it might raise their levels too high.

Therefore, people who are taking thyroid medications or have an overactive thyroid should be cautious when supplementing with tyrosine.

Levodopa (L-dopa)

Levodopa (L-dopa) is a medication commonly used to treat Parkinson’s disease (37Trusted Source).

In the body, L-dopa and tyrosine compete for absorption in the small intestine, which can interfere with the drug’s effectiveness (38).

Thus, doses of these two drugs should be separated by several hours to avoid this.

Interestingly, tyrosine is being investigated for alleviating some of the symptoms associated with cognitive decline in older adults (38, 39Trusted Source).

Summary Tyrosine is safe for
the majority of people. However, it may interact with certain medications.

As a supplement, tyrosine is available as a free-form amino acid or N-acetyl L-tyrosine (NALT).

NALT is more water-soluble than its free-form counterpart, but it has a low conversion rate to tyrosine in the body (40Trusted Source, 41Trusted Source).

This means that you would need a larger dose of NALT than tyrosine to get the same effect, making the free-form the preferred choice.

Tyrosine is commonly taken in doses of 500–2,000 mg 30–60 minutes before exercise, even though its benefits on exercise performance remains inconclusive (42, 43).

It does seem to be effective for preserving mental performance during physically stressful situations or periods of sleep deprivation when taken in doses ranging from 45–68 mg per pound (100–150 mg per kg) of body weight.

This would be 7–10 grams for a 150-pound (68.2-kg) person.

These higher doses may cause gastrointestinal upset and be split into two separate doses, taken 30 and 60 minutes prior to a stressful event.

Summary Tyrosine as a free-form amino acid is the best form of the supplement. Its greatest
anti-stress effects have been observed when it’s taken in doses of 45-68 mg per pound (100–150 mg per kg) of body weight about 60 minutes before a stressful event.

Tyrosine is a popular dietary supplement used for a variety of reasons.

In the body, it’s used to make neurotransmitters, which tend to decrease under periods of stressful or mentally demanding situations.

There is good evidence that supplementing with tyrosine replenishes these important neurotransmitters and improves mental function, compared to a placebo.

Supplementing with it has been shown to be safe, even in high doses, but has the potential to interact with certain medications, warranting caution.

While tyrosine has many benefits, their significance remains unclear until more evidence is available.