Tyrosine - its many important roles

Tyrosine is one of 20 amino acids that your body uses to build proteins, and also serves as a precursor for neurotransmitter production. It is considered a conditionally essential amino acid. This means that your body can synthesize it naturally, but production may be limited during periods of stress, poor diet, etc. Tyrosine passes through a metabolic pathway to produce dopamine, which can then be further processed to produce norepinephrine and epinephrine, as shown in the image below. These chemicals are called catecholamines, and tyrosine is important for maintaining them in healthy levels.

Image source: https://www.wikidoc.org/index.php/File:Tyrosine_metabolism.png

Tyrosine also serves other important roles in the body. It is used to produce thyroid hormones. It is needed to synthesize coenzyme Q10 (if you would like to learn more, check out our previous blog post on CoQ10). Tyrosine is the precursor to the pigment melanin. It can be broken down to form Krebs cycle (see our previous blog) intermediates. Tyrosine is important to the function of many of the body’s signaling pathways due to its incorporation into the structure of receptor proteins called receptor tyrosine kinases. As you can see, tyrosine plays numerous vital roles throughout the body.

Evidence shows that tyrosine supplementation attenuates the loss of cognitive function associated with stressful situations or environments. Catecholamines, especially dopamine, are related to positive mood, motivation, and reward behaviors. Since tyrosine is a precursor to these molecules, it makes sense that supplementation helps the brain persevere through stressful experiences.

As tyrosine is an amino acid, it can be obtained through dietary protein sources. You may then ask, if I get tyrosine from my diet, why supplement it? It turns out that tyrosine is one of multiple amino acids in a class called large-neutral amino acids (LNAA). These LNAAs share a common transporter across the blood brain barrier, and they compete with each other for access to the brain. Increasing the ratio of tyrosine to the other LNAAs in the blood will lead to more tyrosine being transported into the brain, where it is used for neurotransmitter production. It is for this reason that supplementing tyrosine specifically can be helpful, rather than solely relying on diet, which contains large proteins that are a mix of many amino acids.

The best way to know if a supplement is right for you is to speak to your provider, and tyrosine is no exception. Some people may want/need to avoid tyrosine – for example, people taking MAOIs, which inhibit catecholamine breakdown. Since tyrosine plays so many roles throughout the body, there are people who need to be aware that tyrosine supplements might worsen certain specific conditions. As tyrosine is needed for melanin production, a patient with pigmented melanoma should likely avoid it. Patients with overactive thyroid may need to be careful as well, since tyrosine is a precursor to thyroid hormones. To be clear, most people will likely benefit from tyrosine. However, like any supplement or medication, it is always best to talk to your provider before starting a regimen.

References:

Hase, A., Jung, S. E., & Rot, M. a. H. (2015). Behavioral and cognitive effects of tyrosine intake in healthy human adults. Pharmacology Biochemistry and Behavior, 133, 1–6. https://doi.org/10.1016/j.pbb.2015.03.008

Tyrosine. (n.d.). https://healthlibrary.uwmedicine.org/Search/19,Tyrosine

Tyrosine supplementation: Can this amino acid boost brain dopamine and improve physical and mental performance? (n.d.). Gatorade Sports Science Institute. https://www.gssiweb.org/sports-science-exchange/article/sse-157-tyrosine-supplementation-can-this-amino-acid-boost-brain-dopamine-and-improve-physical-and-mental-performance-

Wintheiser, G. A., & Silberstein, P. (2022, September 26). Physiology, tyrosine kinase receptors. StatPearls - NCBI Bookshelf. https://www.ncbi.nlm.nih.gov/books/NBK538532/