L-Tyrosine to alleviate the effects of stress

The main effects of L-tyrosine that have been reported are acute effects in preventing a decline in cognitive function in response to physical stress. The physical stressors include those of interest to the military, such as cold stress, the combination of cold stress and high-altitude stress (i.e., mild hypoxia), extended wakefulness and lower body negative pressure stress (designed to simulate some of the effects of space flight). Doses of L-tyrosine in these studies ranged up to 20 g, many times the normal daily dietary intake. In one study, L-tyrosine was given at a dosage of 2 g per day for 5 days during a demanding military combat training course; it improved various aspects of cognitive function relative to placebo.

How Tyrosine, an Amino Acid, Works in the Body

Tyrosine is an amino acid made by the body. It helps generate brain chemicals called neurotransmitters, including dopamine, epinephrine, and norepinephrine. It shows some evidence of improving focus and mental clarity, especially in stressful or demanding situations. More research is needed to confirm and understand these effects.

While tyrosine supplements are generally safe, they’re not right for everyone. Those with an overactive thyroid (hyperthyroidism) should avoid it, as tyrosine may increase thyroid hormone production. People who get migraines may experience an increase in symptoms with tyrosine supplementation. It’s always best to consult a healthcare provider before adding any supplement to your routine.

In the United States, the Food and Drug Administration (FDA) does not regulate supplements the way it regulates prescription drugs. That means some supplement products may not contain what the label says. When choosing a supplement, look for third-party tested products and consult a healthcare provider, registered dietitian nutritionist (RD or RDN), or pharmacist.

Uses of L-Tyrosine

Supplement use should be individualized and vetted by a healthcare professional, such as a registered dietitian, pharmacist, or healthcare provider. No supplement is intended to treat, cure, or prevent disease.

Tyrosine is made in the body from another amino acid called phenylalanine. It is used in the body to make the catecholamines dopamine and norepinephrine. Under stressful conditions, these catecholamines can be depleted.

Tyrosine is marketed for stress relief, brain health, and improved cognitive function. It is also thought to stimulate thyroid hormone production in people with hypothyroidism (low thyroid function), including those with Hashimoto thyroiditis (the autoimmune form of hypothyroidism).

To date, there is very little evidence to support any of these claims, and most of the evidence involves small studies with variable results.

Getty Images / Olena Ruban

Improved Cognitive Function During Physical Stress

Tyrosine is often marketed to alleviate the effects of stress. The definition of stress is left open to interpretation, but the research supporting tyrosine evaluated its effects during periods of extreme physical stress.

During periods of physical stress, the body releases more catecholamines, resulting in a depletion of their levels.

Studies have evaluated anywhere from 2 grams (g) to 20 g of tyrosine on cognitive performance during periods of prolonged sleep deprivation, exposure to extremely cold temperatures, or during demanding military combat training.

In another study, tyrosine supplementation improved cognitive functioning, such as response inhibition, task switching, and working memory in young adults. However, this was mostly seen in short-term stressful situations or cognitively demanding scenarios.

These studies show improved cognitive function with tyrosine supplementation during extreme physical stress. Therefore, these results don’t necessarily apply to the general population, who may experience mild stress from psychosocial factors or daily activities.

Additionally, taking tyrosine will not help you feel less stressed, which some may mistakenly interpret from the marketing claims.

Phenylketonuria (PKU)

Phenylketonuria (PKU) is an inherited disorder in which the person cannot process phenylalanine appropriately.

Since phenylalanine converts to tyrosine, this could lead to low levels of tyrosine in the body. People with PKU may be advised to consume a diet containing tyrosine and very little phenylalanine to prevent low tyrosine levels.

Research that evaluated tyrosine supplementation in people with PKU found that tyrosine levels in the blood were higher with supplementation. However, there was no difference between the supplement or placebo group in any of the other outcomes measured.

What Are the Side Effects of L-Tyrosine?

Tyrosine is generally recognized as safe (GRAS) by the FDA. As a supplement, tyrosine is mostly safe, although long-term safety and safety in high doses are not known. Studies have used doses of 150 milligrams (mg) per kilogram of body weight (mg/kg) without harmful effects.

Some have reported nausea, fatigue, and headaches with tyrosine supplementation.

Precautions

There is insufficient data on the safety of supplementing tyrosine in pregnant or breastfeeding people. Therefore, sticking to amounts of tyrosine found naturally in foods is safest.

People with hyperthyroidism (overactive thyroid gland) should avoid tyrosine supplements as they can increase thyroid hormone production and worsen symptoms of hyperthyroidism (including Graves’ disease, the autoimmune form of hyperthyroidism).

Tyrosine can also trigger migraine headaches. If you have frequent migraines, avoid tyrosine supplementation.

Dosage: How Much L-Tyrosine Should I Take?

Always speak with a healthcare provider before taking a supplement to ensure that the supplement and dosage are appropriate for your individual needs.

Tyrosine is available in the foods that we eat. Therefore, most people get enough tyrosine from their diet alone.

For adults, the estimated amino acid requirement for phenylalanine and tyrosine combined is 14 mg/kg body weight daily.

Dosage may vary depending on what you’re taking it for. Talk to a healthcare provider or a registered dietitian nutritionist on the most appropriate dosing regimen for you

There is not a lot of data on the effects of high doses of tyrosine or toxicity. The possible ill effects of such high doses over the long term are not known.

Interactions

Some medications may interact with supplemental tyrosine:

• Levodopa is a medication used for Parkinson’s disease. Levodopa and tyrosine can compete for absorption in the small intestine, which could influence how well they work. This can be avoided by dosing tyrosine two hours apart from the levodopa dose. Additionally, high protein intake, in general, may make levodopa less effective. But the benefit of improved efficacy of levodopa should be weighed against the risk of tyrosine deficiency by you and your healthcare provider.
• Monoamine oxidase inhibitors (MAOIs) combined with high-tyramine foods can increase blood pressure to dangerous levels. Tyrosine is broken down to tyramine. In theory, it could affect blood pressure. But it is not yet known if supplementing tyrosine would increase tyramine levels. For now, it is best to avoid tyrosine supplements while prescribed MAOIs and discuss your supplementation needs with your healthcare provider.
• Thyroid medications are used to control levels of thyroid hormones. Supplementing tyrosine may also influence hormone levels and raise levels too high.

It is essential to carefully read the ingredients list and nutrition facts panel of a supplement to know which ingredients and how much of each ingredient is included. Review the supplement label with your healthcare provider to discuss any potential interactions with foods, other supplements, and medications.

How to Store L-Tyrosine

Store tyrosine as you would for other supplements, following the manufacturer’s guidelines for the best shelf life. Always store supplements and medications out of the reach of children and pets to prevent accidental consumption.

Frequently Asked Questions

What are the best food sources of tyrosine?

High-protein foods such as meats, chicken, turkey, fish, and eggs are good sources of tyrosine. You can also get it in some cheeses, like cheddar and cottage cheese, and yogurt.

Can tyrosine improve physical performance in athletes?

There is not enough evidence to suggest that tyrosine alone can improve performance. Preliminary research has found that caffeine, theanine, and tyrosine may improve performance, but caffeine is already known to be an ergogenic aid. Tyrosine also did not improve performance in a hot environment. It also did not have a measurable effect on endurance, muscle strength, or power in healthy men. More research is needed before tyrosine supplementation can be routinely recommended.

Sources of L-Tyrosine and What To Look For

Tyrosine is easy to get through diet alone. High tyrosine foods include:

• Meat, such as chicken or turkey
• Fish
• Dairy products, like cheese, or yogurt
• Eggs
• Soy
• Avocado
• Wheats and oats
• Pumpkin seeds
• Peanuts

Tyrosine supplementation can be found in its free form. It can also be found as N-acetyl L-Tyrosine (NALT). The conversion rate of NALT to tyrosine is lower so some may take higher doses of NALT.

Tyrosine is available as a combination product, with high amounts of several B vitamins. It can also be found combined with iodine. Products are often marketed and labeled for “brain health,” “neurotransmitter support during stress,” or “thyroid support.” As mentioned previously, there is little evidence to support these claims.

When looking for supplements, be sure to find ones that have been third-party tested so that you can trust they contain what the label claims and are free of harmful contaminants.

Summary

Tyrosine is a nonessential amino acid that is produced in the body. It is also easily available in many of the foods we eat. For this reason, a food-first approach to getting more tyrosine is usually preferred.

Tyrosine is marketed to relieve stress, ease symptoms of hypothyroidism, and improve brain health, but there is very little scientific evidence to support any of these claims. Speak with a healthcare provider if you are interested in using supplements of any sort.

15 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

1. Attipoe S, Zeno S, Lee C, et al. Tyrosine for mitigating stress and enhancing performance in healthy adult humans, a rapid evidence assessment of the literature. Military Med. 2015 Jul;180(7):754–765. doi:10.7205/MILMED-D-14-00594
2. Mount Sinai. Tyrosine.
3. Young SN. L-tyrosine to alleviate the effects of stress?J Psychiatry Neurosci. 2007;32(3):224.
4. Neri DF, Wiegmann D, Stanny RR, Shappell SA, McCardie A, McKay DL. The effects of tyrosine on cognitive performance during extended wakefulness. Aviat Space Environ Med. 1995;66(4):313-319.
5. O’Brien C, Mahoney C, Tharion WJ, Sils IV, Castellani JW. Dietary tyrosine benefits cognitive and psychomotor performance during body cooling. Physiol Behav. 2007;90(2-3):301-307. doi:10.1016/j.physbeh.2006.09.027
6. Deijen JB, Wientjes CJ, Vullinghs HF, Cloin PA, Langefeld JJ. Tyrosine improves cognitive performance and reduces blood pressure in cadets after one week of a combat training course. Brain Res Bull. 1999;48(2):203-209. doi:10.1016/s0361-9230(98)00163-4
7. Jongkees BJ, Hommel B, Kühn S, Colzato LS. Effect of tyrosine supplementation on clinical and healthy populations under stress or cognitive demands–a review. J Psychiatr Res. 2015;70:50-57. doi:10.1016/j.jpsychires.2015.08.014
8. Remmington T, Smith S. Tyrosine supplementation for phenylketonuria. Cochrane Database Syst Rev. 2021;1(1):CD001507. doi:10.1002/14651858.CD001507.pub4
9. National Research Council (US) Subcommittee on the Tenth Edition of the Recommended Dietary Allowances. Proteins and amino acids. Washington (DC): National Academies Press (US); 1989.
10. Boelens Keun JT, Arnoldussen IA, Vriend C, van de Rest O. Dietary approaches to improve efficacy and control side effects of levodopa therapy in Parkinson’s disease: a systematic review. Adv Nutr. 2021;12(6):2265-2287. doi:10.1093/advances/nmab060
11. Flockhart DA. Dietary restrictions and drug interactions with monoamine oxidase inhibitors: an update. J Clin Psychiatry. 2012;73 Suppl 1:17-24. doi:10.4088/JCP.11096su1c.03
12. Palinkas LA, Reedy KR, Smith M, et al. Psychoneuroendocrine effects of combined thyroxine and triiodothyronine versus tyrosine during prolonged Antarctic residence. Int J Circumpolar Health. 2007;66(5):401-417.
13. Zaragoza J, Tinsley G, Urbina S, et al. Effects of acute caffeine, theanine and tyrosine supplementation on mental and physical performance in athletes. J Int Soc Sports Nutr. 2019;16(1):56. doi:10.1186/s12970-019-0326-3
14. Tumilty L, Gregory N, Beckmann M, Thatcher R. No influence of low-, medium-, or high-dose tyrosine on exercise in a warm environment. Med Sci Sports Exerc. 2020;52(6):1404-1413. doi:10.1249/MSS.0000000000002245
15. Sutton EE, Coill MR, Deuster PA. Ingestion of tyrosine: effects on endurance, muscle strength, and anaerobic performance. Int J Sport Nutr Exerc Metab. 2005;15(2):173-185. doi:10.1123/ijsnem.15.2.173

By Jennifer Lefton, MS, RD/N, CNSC, FAND
Lefton is a registered dietitian/nutritionist and certified nutrition support clinician with over 20 years of experience in clinical nutrition.

L-Tyrosine to alleviate the effects of stress?

Stress is an inescapable part of human existence and in extreme forms can cause or exacerbate psychiatric disorders, including depression, schizophrenia and posttraumatic stress disorder. Many people feel that their level of stress is above the optimal level, and this probably accounts for the large number of herbal and “natural” compounds sold over the counter in supermarkets and drug stores and sold on the web to help counteract the effects of stress. For many of these compounds, there is little or no evidence of efficacy. However, for one, L-tyrosine, the claims cannot be dismissed summarily. Any patient with even modest Web-searching skills can discover that the ability of L-tyrosine (often referred to on the Web as simply tyrosine) to alleviate the effects of stress is the subject of several publications in respectable journals over the past decade. Most of these articles originated from research units attached to the US military; other publications originated from universities and the Dutch military.

L-Tyrosine is the precursor of the catecholamines; alterations in the availability of L-tyrosine to the brain can influence the synthesis of both dopamine and norepinephrine in experimental animals and probably in humans. In animals, stress increases the release of catecholamines, which can result in the depletion of their levels, an effect that can be corrected by giving L-tyrosine. L-Tyrosine does not seem to enhance the release of catecholamines when neurons are firing at their basal rates, but it does when firing rates are increased by stress. This is the basis for studying the effect of L-tyrosine on the stress response of humans.

The main effects of L-tyrosine that have been reported are acute effects in preventing a decline in cognitive function in response to physical stress. The physical stressors include those of interest to the military, such as cold stress, the combination of cold stress and high-altitude stress (i.e., mild hypoxia), extended wakefulness and lower body negative pressure stress (designed to simulate some of the effects of space flight). Doses of L-tyrosine in these studies ranged up to 20 g, many times the normal daily dietary intake. In one study, L-tyrosine was given at a dosage of 2 g per day for 5 days during a demanding military combat training course; it improved various aspects of cognitive function relative to placebo.

Some of the papers have titles that include the words “dietary tyrosine,” even though L-tyrosine is given without the amino acids that accompany it when it is ingested as part of protein. The use of L-tyrosine in purified form ensures that it is metabolized less via protein synthesis and more by catecholamine synthesis. Given that purified L-tyrosine is handled metabolically in a somewhat different way from ingesting it as part of the diet, calling it a dietary or natural remedy is misleading. Effectively, it is being used as a drug. Safety data on long-term L-tyrosine use in healthy people is lacking. In one of the longest studies, 2.5 g L-tyrosine 3 times daily had no beneficial or adverse effects when given to people with mild essential hypertension for 2 weeks. The measures in this study were limited to heart rate and blood pressure.

Patients or healthy people feeling somewhat stressed may read claims that L-tyrosine alleviates the effects of stress. They probably imagine that L-tyrosine will help them to feel less stressed in response to the psychosocial stressors of everyday life. What has been shown is that L-tyrosine prevents some of the cognitive decline in response to physical stressors, an effect of interest to almost noone outside the military. The use of L-tyrosine cannot be recommended for patients. Patients who are already taking it need to be educated about what it has actually been shown to do and about the lack of evidence for long-term safety.

Simon N. Young, PhD Professor, Department of Psychiatry McGill University Montréal, Que.

Footnotes

The information in this column is not intended as a definitive treatment strategy but as a suggested approach for clinicians treating patients with similar histories. Individual cases may vary and should be evaluated carefully before treatment is provided.

Psychopharmacology for the Clinician columns are usually based on a case report that illustrates a point of interest in clinical psychopharmacology. They are about 500 words long, and references are not necessary.

Please submit appropriate columns online at http://mc.manuscriptcentral.com/jpn; inquiries may be directed to [email protected]

An online bibliography for this column is available in the online version at www.cma.ca.

Articles from Journal of Psychiatry and Neuroscience are provided here courtesy of Canadian Medical Association