Tyrosine: Benefits, Side Effects and Dosage

Tyrosine is a supplement that may enhance alertness, attention, and concentration. Depending on the amount taken, it might boost both physical and cognitive performance. However, not all studies are definitive, and adverse effects are possible.

Tyrosine helps generate vital brain chemicals that facilitate nerve cell communication and can influence mood regulation.

Despite these potential upsides, taking tyrosine supplements can cause side effects and may interfere with certain medications.

This article explains everything you need to know about tyrosine, including its functions, possible advantages, adverse reactions, and suggested dosing.

What Is Tyrosine and What Does It Do?

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

It occurs in numerous foods, especially cheese, where it was initially identified. In fact, “tyros” means “cheese” in Greek.

Tyrosine is also present in chicken, turkey, fish, dairy and most other protein-rich foods.

It contributes to the synthesis of several important compounds, including (4):

• Dopamine: Dopamine governs reward and pleasure pathways. This crucial brain chemical is also essential for memory and motor control.
• Adrenaline and noradrenaline: These hormones drive the fight-or-flight reaction to stress. They ready the body to “fight” or “flee” from perceived danger.
• Thyroid hormones: Produced by the thyroid gland, these hormones chiefly regulate metabolic rate.
• Melanin: This pigment determines the color of your skin, hair and eyes. Individuals with darker skin have greater melanin content than those with lighter skin.

Tyrosine is also offered as a dietary supplement. It is available by itself or blended with other ingredients, such as in pre-workout mixes.

Supplementing with tyrosine is believed to raise levels of the neurotransmitters dopamine, adrenaline and norepinephrine.

By elevating these neurotransmitters, it may help sustain memory and performance under stress (4).

Summary Tyrosine is an amino acid the body synthesizes from phenylalanine. Taking it as a supplement is thought to boost key brain chemicals that influence mood and the stress response.

It May Improve Mental Performance in Stressful Situations

Stress is a universal experience.

Stress can impair reasoning, memory, attention and knowledge by lowering neurotransmitter levels.

For example, animals exposed to cold (an environmental stressor) showed memory problems linked to reduced neurotransmitters (10, ).

However, when these animals received tyrosine, the neurotransmitter drop was prevented and memory function returned.

Although animal findings don’t always apply directly to humans, similar effects have been observed in people.

In one trial of 22 women, tyrosine notably improved working memory during a mentally taxing task compared with a placebo. Working memory is important for focus and following directions.

In another small study, 22 participants received either tyrosine or a placebo before taking a test that measures cognitive flexibility. Tyrosine improved cognitive flexibility relative to placebo.

Cognitive flexibility refers to the ability to switch between tasks or thoughts; faster switching indicates greater flexibility.

Moreover, tyrosine has been shown to help sleep-deprived individuals. A single dose allowed people who had missed a night’s sleep to remain alert for about three hours longer than they would have otherwise.

Two reviews also concluded that tyrosine supplementation can reverse cognitive decline and bolster cognition in short-term, stressful or mentally demanding contexts (15, ).

While tyrosine may offer cognitive advantages, no evidence indicates it improves physical performance in humans.

Finally, there is no research suggesting that taking tyrosine when not under stress will enhance mental performance — it won’t increase baseline brainpower.

Summary Research indicates tyrosine can help preserve cognitive function when taken prior to a stressful task. However, there’s no evidence it enhances memory in non-stressful situations.

It Might Help Those With Phenylketonuria

Phenylketonuria (PKU) is a rare inherited disorder caused by a defect in the gene responsible for producing the enzyme phenylalanine hydroxylase.

This enzyme converts phenylalanine into tyrosine, which is needed to synthesize neurotransmitters (4).

Without this enzyme, phenylalanine accumulates in the body.

The main treatment for PKU is a special diet that restricts phenylalanine-containing foods.

Because tyrosine is produced from phenylalanine, people with PKU can become low in tyrosine, which may contribute to behavioral issues.

Supplementing with tyrosine might be an option to address these symptoms, but the evidence is inconclusive.

One review examined tyrosine supplementation alongside or instead of a phenylalanine-restricted diet and looked at effects on intelligence, growth, nutrition, mortality and quality of life.

The review evaluated two studies with 47 participants and found no benefit of tyrosine over placebo.

An analysis of three studies including 56 people likewise found no meaningful differences between tyrosine supplementation and placebo for the outcomes measured.

The authors concluded there is insufficient evidence to recommend tyrosine supplements for PKU treatment.

Summary PKU is a serious disorder that can lead to tyrosine deficiency. More research is required before tyrosine supplementation can be recommended for management of PKU.

Evidence Regarding Its Effects on Depression Is Mixed

Tyrosine has also been proposed as a treatment for depression.

Depression is believed to stem from imbalances in brain neurotransmitters, and antidepressants aim to correct these imbalances.

Because tyrosine can be converted into neurotransmitters, some claim it acts as an antidepressant.

However, early trials don’t support this assertion.

In one study, 65 people with depression received either 100 mg/kg of tyrosine, 2.5 mg/kg of a standard antidepressant, or placebo daily for four weeks. Tyrosine showed no antidepressant benefit.

Depression is a complex, heterogeneous disorder, which likely explains why a simple dietary supplement such as tyrosine is generally ineffective at treating its symptoms.

Still, depressed individuals who specifically have low dopamine, adrenaline, or noradrenaline levels might benefit from tyrosine.

Indeed, one trial in people with dopamine-deficient depression reported clinically meaningful improvements with tyrosine.

Dopamine-dependent depression is marked by low energy and reduced motivation.

Until more high-quality studies are available, the evidence does not support using tyrosine broadly to treat depression.

Summary Tyrosine can be converted into mood-related neurotransmitters, but current research does not support its routine use to treat depression.

Side Effects of Tyrosine

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

It has been administered safely at 68 mg per pound (150 mg per kg) of body weight per day for up to three months (15, , ).

Although safe for most individuals, tyrosine can cause adverse effects and interact with medications.

Monoamine Oxidase Inhibitors (MAOIs)

Tyramine is an amino compound that helps regulate blood pressure and is formed from the breakdown of tyrosine.

Tyramine can accumulate in foods when tyrosine and phenylalanine are converted into tyramine by microbial enzymes (31).

Foods such as cheddar and blue cheese, cured or smoked meats, soy products and beer contain elevated tyramine levels (31).

MAOI antidepressants block monoamine oxidase, the enzyme that degrades excess tyramine in the body.

Combining MAOIs with high-tyramine foods can dangerously raise blood pressure.

It is unclear whether taking tyrosine supplements leads to significant tyramine accumulation, so those on MAOIs should take precautions (, 35).

Thyroid Hormone

The thyroid hormones triiodothyronine (T3) and thyroxine (T4) regulate growth and metabolism.

It’s important to maintain appropriate T3 and T4 levels.

Tyrosine supplementation may affect these hormones.

Because tyrosine is a precursor for thyroid hormones, adding more could potentially elevate their levels.

Therefore, people taking thyroid medication or with an overactive thyroid should be cautious with tyrosine supplements.

Levodopa (L-dopa)

Levodopa (L-dopa) is commonly prescribed for Parkinson’s disease.

In the gut, L-dopa and tyrosine compete for absorption, which can reduce the drug’s effectiveness (38).

Therefore, doses of these substances should be spaced by several hours to prevent interaction.

Interestingly, tyrosine is being explored for easing some cognitive symptoms associated with aging (38, ).

Summary Tyrosine is safe for most people, but it can interact with particular medications.

How to Supplement With Tyrosine

Tyrosine supplements come in the free-form amino acid or as N-acetyl L-tyrosine (NALT).

NALT dissolves better in water than free-form tyrosine, but it converts to tyrosine less efficiently in the body.

This lower conversion means you’d need a larger NALT dose to achieve equivalent effects, so free-form tyrosine is generally preferred.

Common supplemental doses range from 500–2,000 mg taken 30–60 minutes before exercise, although evidence for exercise performance benefits is inconclusive (42, 43).

Tyrosine appears effective for preserving cognitive function during physically stressful events or sleep loss when dosed at 45–68 mg per pound (100–150 mg per kg) of body weight.

For example, that equates to about 7–10 grams for a 150-pound (68.2-kg) person.

Such higher amounts may cause stomach upset and are often split into two doses taken 30 and 60 minutes before a stressful situation.

Summary Free-form tyrosine is the preferred supplement form. Its most robust anti-stress benefits have been reported with doses of 45–68 mg per pound (100–150 mg per kg) of body weight taken roughly 60 minutes before a stressful event.

The Bottom Line

Tyrosine is a widely used dietary supplement taken for several reasons.

In the body it serves as a precursor for neurotransmitters that tend to fall during stressful or mentally demanding episodes.

Good evidence suggests that tyrosine supplementation replenishes these neurotransmitters and enhances cognitive function compared with placebo in short-term stress conditions.

Tyrosine appears safe even at relatively high doses, but it can interact with certain medications, so caution is warranted.

Although tyrosine offers potential benefits, their full importance remains uncertain pending additional research.