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L-tyrosine: what it does, food sources and research

L-tyrosine is an amino acid your body uses to make dopamine and thyroid hormones. We look at what the research says about focus under pressure, the best food sources and how study doses compare with the 250mg in a can of Hype.

By Louie Syred28 October 20267 min read

L-tyrosine is an amino acid, one of the building blocks of protein, that your body uses to make dopamine, noradrenaline and thyroid hormones. Most people get plenty of it from foods like cheese, soya, meat, fish and seeds. Research suggests it may help thinking under short bursts of stress, such as cold, sleep loss or intense multitasking, though studies use far larger doses than any food or drink provides.

A 2015 review in the Journal of Psychiatric Research concluded tyrosine is most promising for cognition in brief stressful or demanding situations, and has little potential for physical exercise (Jongkees et al. 2015).
In a 2015 study of 22 people, 2g of tyrosine in orange juice made switching between two tasks faster than a placebo when people had time to prepare (Steenbergen et al. 2015, via Leiden University).
Shredded parmesan contains about 2.3g of tyrosine per 100g, according to USDA data (USDA FoodData Central, via GetFoodFacts).
Stress studies have used 100mg to 150mg per kilogram of body weight, which is 7g to 10g for a 68kg adult (Healthline).

What is L-tyrosine?

L-tyrosine is the form of the amino acid tyrosine found in the protein you eat, and the form most supplements use. It is classed as non-essential, because your body can make its own from another amino acid, phenylalanine (Myprotein). It was first identified in cheese (Healthline).

The conversion from phenylalanine matters for people with phenylketonuria, or PKU, an inherited condition in which the body cannot turn phenylalanine into tyrosine because an enzyme called phenylalanine hydroxylase is missing or not working. In England, babies are checked for PKU through the NHS newborn blood spot test (NHS Genomics Education).

What does L-tyrosine do in the body?

Tyrosine is a starting material for several important chemical messengers. Your body uses it to make dopamine, adrenaline, melanin, the pigment in skin and hair, and the thyroid hormones (Myprotein). It is also used to make noradrenaline, and together with dopamine and adrenaline these messengers are known as catecholamines (Jongkees et al. 2015).

One theory behind the research is that intense stress, such as extreme cold, can lower levels of these messengers, and in animal studies extra tyrosine reversed the effect of cold on memory (Healthline). That idea explains why most studies test tyrosine in tough conditions rather than on an ordinary day.

Does L-tyrosine help focus under pressure?

This is where most of the interest lies, and the evidence is promising but limited. In 2015, Jongkees and colleagues reviewed the cognitive and behavioural studies of tyrosine. They found that results conflict, and concluded that tyrosine improves thinking when dopamine or noradrenaline is temporarily running low in an otherwise healthy brain, and that the benefit shows up mainly in those conditions (Jongkees et al. 2015).

A few studies show what that looks like in practice.

Military training. In 1999, Deijen and colleagues followed 21 cadets on a demanding combat training course. The 10 who had a protein-rich drink containing 2g of tyrosine did better on memory and tracking tasks on day six than the 11 who had a carbohydrate drink with the same calories. Their systolic blood pressure was also lower, and mood showed no difference (Deijen et al. 1999).
Switching between tasks. In 2015, 22 people drank orange juice with either 2g of tyrosine or a placebo, one week apart. An hour later, when they had time to prepare, they switched between judging letters and judging numbers significantly faster after tyrosine (Steenbergen et al. 2015, via Leiden University).
Working memory. In a study of 22 women, tyrosine improved working memory during a mentally demanding multitasking test compared with a placebo (Healthline).

A 2015 evidence assessment for the journal Military Medicine looked at 14 controlled trials, and reported that all six studies of thinking under stressors such as sleep loss, extreme climates and combat training showed some benefit to attention, reaction time or memory (Attipoe et al. 2015, summarised by AOR).

Not every trial is positive. In a small 2015 University of Bedfordshire study, presented as a conference abstract, eight men took a large dose of tyrosine before a long walk carrying a 25kg pack at 40°C, and it made no difference to their thinking or their time trial compared with a placebo (Coull et al. 2015). The fair summary is that tyrosine looks most useful for the mind during short, intense pressure, and that the studies are small.

Is L-tyrosine good for exercise?

Probably not, at least on its own. The 2015 Jongkees review saw little potential for tyrosine to improve physical exercise, likely because exercise depends on many other factors (Jongkees et al. 2015). One 2011 study found cyclists in 30°C heat kept going 15% longer on average after tyrosine, but this rests on a single study and the wider evidence is far less conclusive (Myprotein).

Which foods contain L-tyrosine?

Any food rich in protein gives you tyrosine. WebMD lists sesame seeds, cheese, soya beans, meat and poultry, fish and nuts among the best sources, and notes that most people do not need a supplement, because a balanced diet provides enough (WebMD). USDA figures give a sense of scale.

Food	Tyrosine per 100g	Worth knowing
Soya protein isolate	3.2g	A concentrated powder used in shakes and plant-based foods
Dried spirulina	2.6g	Usually eaten a teaspoon at a time
Shredded parmesan	2.3g	About 11g of parmesan holds the 250mg in a can of Hype
Low-fat sesame flour	2.1g	Sesame seeds and tahini are everyday sources
Defatted peanut flour	2.1g	Peanuts and peanut butter are everyday sources
Dried whole egg	2.0g	Fresh eggs contain less per 100g because of their water

Figures are from USDA FoodData Central, via GetFoodFacts. Many of the highest entries are dried or concentrated foods, so fresh versions contain less per 100g. There is no official recommended daily amount for tyrosine.

How much L-tyrosine do studies use?

Study doses are large. For stress and sleep loss, researchers have used 100mg to 150mg per kilogram of body weight, which works out at roughly 7g to 10g for a 68kg adult, often split and taken 30 to 60 minutes before the demanding task (Healthline). Pre-workout products tend to contain 300mg to 600mg (BarBend), and the task-switching study above used 2g.

Healthline also says free-form L-tyrosine is the preferred form. N-acetyl L-tyrosine, or NALT, dissolves more easily in water but converts poorly to tyrosine in the body, so you need more of it for the same result (Healthline).

Who should be careful with L-tyrosine?

Tyrosine from food is part of a normal diet. Doses of up to 150mg per kilogram a day for up to three months have been considered safe in studies, though higher doses may cause stomach upset, and Healthline highlights three groups who should take extra care (Healthline).

People taking MAOIs, a type of antidepressant, because of a possible risk of a dangerous rise in blood pressure.
People taking thyroid medication or with an overactive thyroid, because tyrosine is a building block of thyroid hormones.
People taking levodopa for Parkinson's, because the two compete for absorption in the gut.

For people with PKU, a 2021 Cochrane review of three trials with 56 participants found no evidence that tyrosine should be routinely added to the diet, so this is a decision for their specialist team (Cochrane 2021). If you take any regular medication, ask your GP or pharmacist before trying a supplement.

Why is there L-tyrosine in Peak Hype?

Every can of Peak Hype contains 250mg of L-tyrosine, alongside 60mg of natural caffeine from guayusa and B vitamins. Hype is a lightly sparkling berry citrus drink with 28 calories in a 250ml can. It is vegan and low in sugar, and our line for it is lifted, not wired.

To be clear about the numbers, 250mg is a fraction of the grams used in the studies above, and we make no claim that Hype or its tyrosine affects focus, memory or mood. Hype's caffeine comes from guayusa, the Amazon leaf our founder Louie Syred has drunk every day since 2020. Our guide to guayusa tells the story of the leaf. Our guide to whether all caffeine is the same looks at whether the source of caffeine changes how it feels, and our piece on ADHD and caffeine looks at why caffeine affects people differently.

Hype contains caffeine and is not recommended for children or for women who are pregnant or breastfeeding. If you would rather skip caffeine, Peak Calm is our caffeine-free mood, made to leave you relaxed, not tired.

Meet Hype, made with guayusa and L-tyrosine.

Common questions

What does L-tyrosine do?

L-tyrosine is an amino acid your body uses to make dopamine, noradrenaline, adrenaline, melanin and thyroid hormones. Research suggests extra tyrosine may help thinking during short, intense stress, such as cold, sleep loss or heavy multitasking, though the studies are small.

Can you get enough L-tyrosine from food?

Most people can. Protein foods such as cheese, soya, meat, fish, nuts and seeds all contain it, and your body can also make tyrosine from phenylalanine. WebMD notes that deficiency is unlikely with a balanced diet.

When do people take L-tyrosine?

Healthline suggests taking it 30 to 60 minutes before a stressful event, and the 2015 task-switching study tested people one hour after a 2g dose. Study doses were in grams, far more than a food or drink serving.

Is L-tyrosine safe?

Tyrosine is a normal part of the protein in your diet. Studies have generally found supplements safe for healthy adults over short periods, though higher doses may cause stomach upset. People taking MAOIs, thyroid medication or levodopa, and people with PKU, should speak to their doctor first.