L-tyrosine (also referred to as tyrosine) is an amino acid. It is considered a nonessential amino acid since the body can make tyrosine from another amino acid, phenylalanine.
Tyrosine has several functions in the body, including: 4 Hydroxyphenylalanine
Tyrosine is found in many foods we eat, like eggs, chicken, turkey, fish, soy, cheese, yogurt, and some nuts and seeds. It is also available in supplement form.
This article reviews everything you should know about tyrosine supplementation.
Dietary supplements are not regulated like drugs in the United States, meaning the Food and Drug Administration (FDA) does not approve them for safety and effectiveness before products are marketed. When possible, choose a supplement tested by a trusted third party, such as U.S. Pharmacopeia (USP), ConsumerLab.com, or NSF.
However, even if supplements are third-party tested, they are not necessarily safe for all or effective in general. Therefore, it is important to talk to your healthcare provider about any supplements you plan to take and check in about potential interactions about other supplements or medications.
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 brain health, stress reduction, improved cognitive function, thyroid health, and more. Yet, there is very little evidence that it works, and most of the research includes small studies in very specific situations.
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) 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.
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.
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 thyroid disorders should avoid supplementing tyrosine. Supplemental tyrosine may increase thyroxine levels, ultimately worsening hyperthyroidism or Graves' disease.
Tyrosine can also trigger migraine headaches. If you have frequent migraines, avoid tyrosine supplementation.
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.
Some medications may interact with supplemental tyrosine:
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.
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.
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.
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.
Tyrosine is easy to get through diet alone. High tyrosine foods include:
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.
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 aid stress, thyroid disorders, and cognitive function or brain health, but very little science supports these claims. Talk to a healthcare provider or registered dietitian nutritionist if you're interested in supplementation.
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By Jennifer Lefton, MS, RD/N, CNSC, FAND Jennifer Lefton, MS, RD/N-AP, CNSC, FAND is a Registered Dietitian/Nutritionist and writer with over 20 years of experience in clinical nutrition. Her experience ranges from counseling cardiac rehabilitation clients to managing the nutrition needs of complex surgical patients.
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