L-Tyrosine Known and unknown facts about the amino acid
L-tyrosine is a non-essential amino acid that is part of the proteins in our body. This means that normally our body can only synthesize enough tyrosine by converting another amino acid – L-phenylalanine. Tyrosine is always present – in our food, in our supplements, even in some drinks.
Table of Contents
What is tyrosine?
L-tyrosine (hereinafter referred to as tyrosine) is an amino acid that is used to form norepinephrine and dopamine, has anti-stress properties and can help memory in certain situations.
Usually, our body can only synthesize enough tyrosine by converting another amino acid – L-phenylalanine.
However, in certain circumstances, such as phenylketonuria, this is not possible and tyrosine becomes an essential amino acid that must be taken with food or supplements. For these reasons, the tables of recommended daily intake of nutrients contain the column “phenylalanine + tyrosine” and do not give the daily requirement of these two amino acids separately.
Main physiological effects of tyrosine
Tyrosine is part of most proteins in our body. In addition, it is a starting substance from which our body produces the so-called. catecholamines or neurotransmitters (hormones involved in the conduction of a nerve impulse in the nervous system). These include: dopamine, dihydroxyphenylalanine, norepinephrine and epinephrine (in the central and peripheral nervous system and adrenal glands) and thyroxine and triiodothyronine from the thyroid gland. The pigment melanin (which gives brown skin and hair) is also formed by tyrosine.
After ingestion, L-tyrosine is absorbed by the body in the small intestine through sodium-dependent active transport. It is then transported to the liver by the bloodstream. There, L-tyrosine is involved in a number of processes, incl. protein synthesis and oxidative metabolic reactions. This part of it, which is not absorbed by the liver, is transported to a number of tissues of the body through the circulatory system.
Tyrosine is rapidly and easily absorbed in the serum. Peak levels are maintained within 2 to 4 hours after ingestion.
Which foods contain L-tyrosine?
Tyrosine is found in all proteins of plant or animal origin, with yogurt, turkey, seafood, tofu, tuna and legumes such as beans and soy being particularly rich in tyrosine.
Proven and potential benefits in humans
- Positive effects on memory and cognitive function by increasing norepinephrine levels. Tyrosine intake alone does not improve baseline memory, but it can maintain memory quality in the presence of a stress factor;
- Potential benefits for increased attention in children with ADHD. Used in combination with 5-HTP;
- Counteracts drowsiness with stress and excessive fatigue;
- Counteracts the side effects of stress caused by excessive cold;
- Improves energy, mood and counteracts fatigue from excessive physical stress. Improves overall well-being in times of stress;
- It may increase blood pressure at rest, but some studies suggest lowering blood pressure as a result of stress;
- Potential benefits for improving physical performance during periods of severe stress on the nervous system. Does not improve physical properties systematically.
Proven and potential benefits in animals / in vitro
Strong anti-stress agent. Unlike adaptogens, which help in the long run, tyrosine exhibits fast and short properties; Potential benefits for counteracting neurodegenerative processes. It is due to the antioxidant properties of catecholamines synthesized using tyrosine.
Optimal doses and method of administration
Through his diet, the adult should take 33 mg / kg body weight / day, which usually means from 2.8 to 6.4 grams per day. In case of additional intake through supplements, it is usually taken from 0.5 to 2 grams per day.
At this stage, it is assumed that the only reasonable intake of tyrosine as a dietary supplement is before a stressful situation. Such a situation can be understood as training, other physical or mental load.
In these cases, a shock dose of 500 to 2000 mg is recommended, 30-60 minutes before the stressful situation. If a high dose of the amino acid causes gastrointestinal problems, the dose can be divided into two doses. Take one half 60 minutes and the other 30 minutes before exercise. Safe doses of tyrosine as a dietary supplement reach 100-150 mg / kg body weight / day.
Forms of L-tyrosine
Tyrosine is mainly available in the form of the free amino acid. However, alternatives are also available on the market, including N-acetyl-L-tyrosine (NALT). NALT is a more stable form in solution and at high temperatures and is deacetylated in the kidneys. For the time being, there is no definite data on the practical benefits of NALT and the advantages of this form over L-tyrosine in free form. NALT intake has been shown to increase tyrosine concentrations, but much of the complex form is also excreted in the urine.
Side effects and contraindications
As tyrosine is found in large quantities in many foods, no serious side effects have been observed so far from its use (even in large quantities) by healthy people. Nervousness and insomnia have been observed in only a small proportion of people taking extra tyrosine. Potential side effects of tyrosine may occur at the following doses:
- Increased heart rate and increase in blood pressure at doses between 100 and 150 mg / kg body weight;
- Decrease in THS (thyroid-stimulating hormone) by up to 30% when taken at 10-12 g daily;
- Excitement, dryness, diarrhea, nausea and vomiting at doses of 2500 to 3000 mg daily.
The use of supplements containing tyrosine is contraindicated in people with melanoma, with congenital metabolic diseases (alkaptonuria and tyrosinemia type I and type II), as well as those allergic to it. It is possible that the additional use of tyrosine causes or exacerbates chronic migraine, and the exact mechanism is unclear. One of the main hypotheses is that too high levels of tyrosine in the body can cause chronic migraines. The main reason is probably the residual amines that are formed during the conversion of tyrosine to l-dopa.
Also avoid the use of antidepressants (eg phenelzine sulphate), which act by inhibiting the enzyme monoamine oxidase. This enzyme breaks down catecholamines in our body, and if we block its action with antidepressants and, on the other hand, take extra tyrosine, this can lead to a dangerous increase in blood pressure. Tyrosine should not be taken with medications such as levodopa, thyroid medications and MAOIs.
It is not recommended to take tyrosine in phenylketonuria. This is a condition in which the body cannot metabolize the amino acid L-phenynalanine and its levels can become toxic. The data are preliminary and not definite, but the recommendations are there.
With what supplements to combine L-tyrosine?
As a dietary supplement, L-tyrosine is most commonly used for pre-workout energy, a stimulator of cognitive function and memory, and fat burning. For fat burning tyrosine can be combined with:
- Thermogenics such as synephrine, caffeine and green tea; Lipotropic substances such as carnitine,
- CLA and alpha lipoic acid.
For pre-stress stimulation (physical and mental), tyrosine can be combined with proven nootropics such as caffeine, acetyl L-carnitine, choline, DMAE and Alpha-GPC. From the BB-Team we are convinced that a combination of tyrosine with caffeine and DMAE / Alpha-GPC can be a faithful helper not only before a strong mental load at work, but also before strenuous training, especially those with predominant strength exercises. . L-tyrosine is one of our selected supplements in the article “How to assemble a pre-workout stack without stimulants?”. You can read more about L-tyrosine or amino acid-related substances in the following materials:
- Neurotransmitters;
- L-DOPA;
- Phenylethylamine.
Sources used :
- https://examine.com/supplements/l-tyrositsf
- Tyrosine supplementation for phenylketonuria. Webster D, Wildgoose J.
- Tyrosine supplementation for phenylketonuria. Poustie VJ, Rutherford P.
- N-acetyl-L-tyrosine and N-acetyl-L-cysteine as tyrosine and cysteine precursors during intravenous infusion in humans. Magnusson I, Ekman L, Wångdahl M, Wahren J.
- Pathogenesis of migraine: role of neuromodulators. D’Andrea G, D’Arrigo A, Dalle Carbonare M, Leon A.
- Tyrosine improves working memory in a multitasking environment. Thomas JR, Lockwood PA, Singh A, Deuster PA.
- Effect of tyrosine on cognitive function and blood pressure under stress. Deijen JB, Orlebeke JF.
- Psychoneuroendocrine effects of combined thyroxine and triiodothyronine versus tyrosine during prolonged Antarctic residence. Palinkas LA, Reedy KR, Smith M, Anghel M, Steel GD, Reeves D, Shurtleff D, Case HS, Van Do N, Reed HL.
- Role of N-terminus of tyrosine hydroxylase in the biosynthesis of catecholamines. Nakashima A, Hayashi N, Kaneko YS, Mori K, Sabban EL, Nagatsu T, Ota A.
- Elevation of plasma tyrosine after a single oral dose of L-tyrosine. Glaeser BS, Melamed E, Growdon JH, Wurtman RJ.
- A study of plasma free amino acid levels. II. Normal values for children and adults. Armstrong MD, Stave U.
- Tyrosine reverses a cold-induced working memory deficit in humans. Shurtleff D, Thomas JR, Schrot J, Kowalski K, Harford R.
- Tyrosine improves behavioral and neurochemical deficits caused by cold exposure. Yeghiayan SK, Luo S, Shukitt-Hale B, Lieberman HR.
- Treatment of attention deficit hyperactivity disorder with monoamine amino acid precursors and organic cation transporter assay interpretation Marty Hinz,Alvin Stein, Robert Neff, Robert Weinberg and Thomas Uncini
- The effects of tyrosine on cognitive performance during extended wakefulness. Neri DF, Wiegmann D, Stanny RR, Shappell SA, McCardie A, McKay DL.
- Effects of coping behavior in different warning signal conditions on stress pathology in rats. Weiss JM.
- Behavioral and neurochemical effects of dietary tyrosine in young and aged mice following cold-swim stress. Brady K, Brown JW, Thurmond JB.
- Treatment with tyrosine, a neurotransmitter precursor, reduces environmental stress in humans. Banderet LE, Lieberman HR.
- Tyrosine improves cognitive performance and reduces blood pressure in cadets after one week of a combat training course. Deijen JB, Wientjes CJ, Vullinghs HF, Cloin PA, Langefeld JJ.
