In this blog post, I will walk you through the potential health benefits of N-Acetyl L-Tyrosine, an amino acid precursor to neurotransmitters that help with cognitive function. Find out why it’s one of the ingredients in our Seneca Nootropic Complex.
Table of Contents
What is N-Acetyl L-Tyrosine?
N-Acetyl L-Tyrosine (NALT) is a form of L-Tyrosine with an added acetyl group, making NALT more bioavailable. This helps NALT cross the blood-brain barrier more easily, so it can move into the brain.
Tyrosine is a precursor to the Catecholamines: Dopamine, Norepinephrine, and Epinephrine. All 3 act as neurotransmitters, with norepinephrine and epinephrine also being hormones.
All 3 of these neurotransmitters are vital for cognitive processing, focus, motivation, and memory. Both stress and not getting enough tyrosine through the diet can affect our ability to produce these neurotransmitters. Fortunately, supplementing with tyrosine can correct any reduction in cognitive function and deficiency in catecholamine levels caused by stress (1).
Thyroid Hormone
Tyrosine is also used as the base from which we make all the thyroid hormones T4, T3, and reverse T3. Every cell in the body uses thyroid hormones. Think of these hormones as accelerators on a car. The higher our thyroid hormones (at least levels of T3 and T4, as reverse T3 acts a little like a break), the more energy we have.
To make the thyroid hormones, 4 molecules of iodine are added to tyrosine to make T4. And 3 molecules of iodine are added to tyrosine to make T3 and reverse T3 (2).
Ensuring Adequate Tetrahydrobiopterin Levels
Tyrosine is considered a conditionally essential amino acid. We can make it from the amino acid phenylalanine, but it requires essential resources to make the conversion. The essential resource is Tetrahydrobiopterin (BH4 or Biopterin for short).
Biopterin is also vital for the production of serotonin and melatonin. Additionally, it’s also important for Nitric Oxide, an essential molecule for heart health. Nitric Oxide relaxes the blood vessels, which helps increase blood flow and oxygen delivery (3).
Biopterin also stops Nitric Oxide from turning into peroxynitrite, which is formed from the free radical superoxide. Peroxynitrite is a powerful oxidant that can cause a lot of damage to the body.
By ensuring we have adequate levels of tyrosine necessary to make both catecholamines and thyroid hormones, we can avoid using the body stores of biopterin.
N-Acetyl L-Tyrosine (NALT) vs L-Tyrosine
Comparing NALT to L-Tyrosine is an active discussion in supplementation circles, especially in the nootropics niche. NALT is more soluble and more stable at blood PH, so it should be more bioavailable than L-Tyrosine. However, a ‘should’ doesn’t mean that it actually is.
First reason why NALT is better
Several studies have shown plasma tyrosine levels significantly increased after oral supplementation with L-Tyrosine. Increases have ranged from 130% to 276% in blood tyrosine levels. These studies used 100mg/kg to 200mg/kg of L-Tyrosine daily. So, for a 70kg adult, that would equal 7,000mg of L-Tyrosine per day (4, 5, 6, 7).
On the other hand, another study that supplemented volunteers with 5000mg of NALT daily only increased blood tyrosine levels by 25%. Most of the NALT ended up in urine.
At first glance, it may seem like L-Tyrosine is the better option. However, I actually think differently. The study makes it clear that if you want to use an IV to increase tyrosine levels, such as for patients who cannot eat, then it should only be done using much lower levels of tyrosine.
Using an IV for NALT completely bypasses the enzymes that remove the acetyl group from NALT (the majority are in the gut). The remainder of these enzymes (mostly in the kidney) become saturated when infused with high doses of NALT. This means the enzymes can’t deacetylate all of the NALT, leading to NALT’s excretion (8). So, smaller concentrations of NALT mixed in with fats, carbs, and other amino acids will likely work much better.
Second reason why NALT is better
Another reason I prefer NALT over L-Tyrosine is because people seem to notice a bigger difference with NALT. While this is anecdotal over ‘real science,’ real science can sometimes have problems, just as sometimes anecdotal data can give a really good picture. Yes, it’s important to look at all the experimental data we have available. But it’s also crucial to look at the overall picture. And on that basis, I prefer to recommend NALT.
Show Me The Science!
Tyrosine as a Nootropic
Dopamine, Norepinephrine, and Epinephrine deficiencies can occur due to tyrosine deficiencies. Fortunately, tyrosine supplementation (such as with our Seneca Nootropic Complex) can correct that. Supplementation can help maintain adequate levels when we use catecholamine neurotransmitters faster, especially during stressful times (9).
However, while tyrosine supplementation can correct deficiencies, it is unlikely to increase neurotransmitter levels over what is ‘normal’ for your brain. This explains why sometimes people can take tyrosine and experience a plateau effect after a week or so. They stop feeling an improvement, and often, they think they’ve reached a tolerance.
However, it seems more likely that they have corrected any pre-existing deficiency and reached peak benefit from tyrosine. Having said that, tyrosine is still an important part of the overall nootropic picture, even when the deficiency has been corrected.
Related article: What Are Nootropics and Cognitive Enhancing Supplements?
Tyrosine and Cognitive Flexibility
Cognitive flexibility can be thought of a little bit like brain fitness. It measures how well someone can adapt to new situations and stimuli.
Researchers tested 22 healthy adults in a task-switching paradigm in a double-blind, placebo-controlled study. They first put the subjects on one type of cognitive test, such as visual recall. Then they swapped to a different type of test, such as mental arithmetic. And then back to the first test, and so on. At the end of the study, the group taking tyrosine performed significantly better on the tests than those given a placebo (10).
In a further study, tyrosine supplementation improved the performance of sleep-deprived adults. Notably, though, the improvement was to a lesser extent than amphetamines which were also tested during the experiment (11). Tyrosine also helped increase deep thinking, which is great for musing on the meaning of life (12)!
Improved cognitive performance following exercise and heat stress
This study tested football players (as in soccer) on a 90-minute football simulated test in a warm environment of 77°F (25°C). They gave half of the subjects tyrosine before the task. Then they tested them halfway through and again at the end of the 90-minute test.
The researchers found that both cognitive performance and mental effort increased in the subjects that took tyrosine at both the halfway and full-time tests (13).
Cognitive function, blood pressure, and heart rate during stress
A Dutch study looked at tyrosine supplementation to help improve cognitive function, heart rate, and blood pressure. The researchers put 16 healthy young subjects through a number of cognitive tests after exposure to an acute stressor. In this case, the stressor was loud noise at 90dB.
The subjects scored better on cognitive tests after supplementing with tyrosine. They also had lower diastolic blood pressure. However, there was no difference in systolic blood pressure or heart rate (14).
Conclusion
As you’ve learned in this article, choosing N-Acetyl L-Tyrosine over L-Tyrosine has a lot of upsides. You get to enjoy a cognitive boost even during stressful times, such as sustained work periods and sleep loss. If you need help with this right now, consider supplementing with NALT. Each serving of our Seneca Nootropic Complex contains 250mg of NALT, along with other natural nootropic ingredients!
Related article: Seneca Nootropic Complex 101: What Makes This Nootropic Stack So Good?
References
(1) Behavioral and cognitive effects of tyrosine intake in healthy human adults, Adrian Hase, Sophie E Jung, Marije aan het Rot, Pharmacol Biochem Behav . 2015 Jun;133:1-6.
(2) Interactions of peroxynitrite, tetrahydrobiopterin, ascorbic acid, and thiols: implications for uncoupling endothelial nitric-oxide synthase, Nermin Kuzkaya, Norbert Weissmann, David G Harrison, Sergey Dikalov, J Biol Chem . 2003 Jun 20;278(25):22546-54.
(3)Chemistry of Thyroid Hormones, VIVO Pathophysiology: http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/thyroid/chem.html
(4) Elevation of plasma tyrosine after a single oral dose of L-tyrosine, B S Glaeser, E Melamed, J H Growdon, R J Wurtman, Life Sci . 1979 Jul 16;25(3):265-71.
(5) Randomised controlled trial of tyrosine supplementation on neuropsychological performance in phenylketonuria, M L Smith, W B Hanley, J T Clarke, P Klim, W Schoonheyt, V Austin, D C Lehotay, Arch Dis Child . 1998 Feb;78(2):116-21.
(6) Effect of high-dose tyrosine supplementation on brain function in adults with phenylketonuria, J Pietz, R Landwehr, A Kutscha, H Schmidt, L de Sonneville, F K Trefz, J Pediatr . 1995 Dec;127(6):936-43.
(7) Increased neurotransmitter biosynthesis in phenylketonuria induced by phenylalanine restriction or by supplementation of unrestricted diet with large amounts of tyrosine, C Lykkelund, J B Nielsen, H C Lou, V Rasmussen, A M Gerdes, E Christensen, F Güttler, Eur J Pediatr . 1988 Dec;148(3):238-45.
(8) Amino Acid Solutions for Premature Neonates During the First Week of Life: The Role of N-Acetyl-L-Cysteine and N-Acetyl-L-Tyrosine, J.B. Van Goudoever MD, PHD, E.J. Sulkers MD, PHD, M. Timmerman, J.G.M. Huijmans PHD, K. Langer PHD, V.P. Carnielli MD, PHD, P.J.J. Sauer MD, PHD, Journal of Parenteral and Enteral Nutrition, Volume 18, Issue 5 p. 404-408
(9) Effect of tyrosine supplementation on clinical and healthy populations under stress or cognitive demands–A review, Bryant J Jongkees, Bernhard Hommel, Simone Kühn, Lorenza S Colzato, J Psychiatr Res . 2015 Nov;70:50-7.
(10) Tyrosine promotes cognitive flexibility: evidence from proactive vs. reactive control during task switching performance, Laura Steenbergen, Roberta Sellaro, Bernhard Hommel, Lorenza S Colzato, Neuropsychologia . 2015 Mar;69:50-5.
(11) Effects of tyrosine, phentermine, caffeine D-amphetamine, and placebo on cognitive and motor performance deficits during sleep deprivation, Richard A Magill, William F Waters, George A Bray, Julia Volaufova, Steven R Smith, Harris R Lieberman, Nancy McNevin, Donna H Ryan, Nutr Neurosci . 2003 Aug;6(4):237-46.
(12) Food for creativity: tyrosine promotes deep thinking, Lorenza S Colzato, Annelies M de Haan, Bernhard Hommel, Psychol Res . 2015 Sep;79(5):709-14.
(13) Effect of tyrosine ingestion on cognitive and physical performance utilising an intermittent soccer performance test (iSPT) in a warm environment, Nicole A Coull, Samuel L Watkins, Jeffrey W F Aldous, Lee K Warren, Bryna C R Chrismas, Benjamin Dascombe, Alexis R Mauger, Grant Abt, Lee Taylor, Eur J Appl Physiol . 2015 Feb;115(2):373-86.
(14) Effect of tyrosine on cognitive function and blood pressure under stress, J B Deijen, J F Orlebeke, Brain Res Bull . 1994;33(3):319-23.
