Tyrosine (N-Acetyl L-Tyrosine) is a non-essential amino acid that acts as a dopamine precursor and hence produces profound effects on memory and mental flexibility.

This amino acid is capable of enhancing many aspects of cognitive abilities, especially under stress. Several studies showed that military personnel and astronauts exposed to cold and altitude stressors were able to withstand these much better with increased tyrosine intake. Tyrosine has also been shown to increase concentration and attention as well as memory formation. 


N-Acetyl-L-Tyrosine, Tyrosine, L-Tyrosine, NALT.


Supports working memory, mental flexibility, and information processing

Supports adaptation to stressful circumstances

What is tyrosine?

Despite the reliance of nootropics enthusiasts on new synthetic research chemicals, often the most profound cognitive enhancing drugs are none other than amino acids and nutrients. Tyrosine is a non-essential amino acid, which is essential for the function of numerous cognitive features.

Tyrosine is most often used as a reliable dopamine precursor in addition to other brain chemicals like epinephrine and adrenaline [1]. N-acetyl-L-tyrosine (NALT) is an acetylated form of the amino acid L-tyrosine. NALT (as well as L-tyrosine) is used as a nootropic because it acts as a precursor for the critical brain neurotransmitter dopamine. Dopamine has a significant role in brain activities linked to reward, motivation, and pleasure, and plays a crucial part in modulating focus, motivation, cognitive flexibility, and emotional resilience. In addition to these creative-productive capacities and states, dopamine is one of the primary regulators of motor control and coordination of body movements, so it is also essential for exercise and muscle performance. Supplying NALT (or other sources of L-tyrosine) for cognitive support may be especially useful when participating in more demanding or stressful tasks [2]. Oral NALT has increased brain levels of L-tyrosine [3].

Tyrosine was found to enhance mental performance with greater benefits recorded as tasks progressed from easier (1-BACK) to more difficult (2-BACK) [14].



N-acetyl-L-tyrosine (NALT) is an acetylated form of the amino acid L-tyrosine; it has better solubility in water, so it is a more functional form than L-tyrosine for use in liquids.

N of 1, i.e., individual response, subjective feedback in the community of users suggests that NALT is experienced somewhat differently, and often at much lower doses than the more commonly used L-tyrosine.

Marco’s Grounds uses a NALT that is sourced from family-owned organic farm and is non-GMO, gluten-free, and vegan.


N-acetyl-l-tyrosine (NALT) seems to be experienced somewhat differently (and often at lower doses) than L-tyrosine. NALT is interesting because real-world experience of people taking it in the community of users does not match up with the bioavailability data. Marco’s Grounds believes it’s essential to consider bioavailability data, but not place too much weight on it. Especially, with ingredients like NALT, where almost all of the bioavailability studies have been either in animals, non-oral dosing (i.v, i.p. etc.), and usually both. During our formulation and testing process, the NALT form has been additive in the context of an overall formula at doses that are typically much lower than would be expected based on bioavailability data and research on L-tyrosine. We also believe that the supplementation of tyrosine, no matter which form is used, is subject to threshold responses (see Marco’s Grounds Dosing Principles). This is due to the tyrosine-induced increase in dopamine synthesis being regulated by end-product inhibition, i.e., once the optimal level is reached, higher levels of tyrosine will no longer increase dopamine synthesis) [3].




Brain function

Supports working memory [14–20]

Supports cognitive flexibility [21] 

Supports logical reasoning [15]

Supports mathematical processing [15]

Supports convergent (“deep”) thinking—a component of creativity [22] 

Supports perceptual-motor task performance [16,23]

Supports inhibition of behavioral responses—a cognitive control function [24]

Precursor for catecholamine synthesis (dopamine, noradrenaline, and adrenaline) [5] 

Supports the rate of dopamine synthesis and release upon neuronal activation [6–11]

Supports norepinephrine synthesis and release upon neuronal activation [11–13]

Protects from neurotransmitter (DA, NE) depletion due to increased brain activity [2]

Protects from performance decline during cognitively demanding tasks [2]


Protects from the adverse effects of stress on cognitive performance [16–19,23]

Protects from adverse behavioral responses to environmental stress [25]

Protects from stress-induced decreases in norepinephrine levels [26]

Protects from stress-induced increases in blood pressure [16,23] 

Supports global mood [27]


Citicoline, Mucuna Pruriens, Phenylalanine, Phenylethylamine, Hordenine, Phosphatidylserine, Rhodiola Rosea, Vitamin C



Clinically Studied

Pharmaceutical Grade Cognitive and Mind Enhancing Complex
Made in Switzerland


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  2. Jongkees, B. J., Hommel, B., Kühn, S., & Colzato, L. S. (2015). Effect of tyrosine supplementation on clinical and healthy populations under stress or cognitive demands—A review. Journal of psychiatric research, 70, 50-57.
  3. Topall, G., & Laborit, H. (1989). Brain tyrosine increases after treating with prodrugs: comparison with tyrosine. Journal of pharmacy and pharmacology, 41(11), 789-791.
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  7. Wurtman, R. J., Larin, F., Mostafapour, S., & Fernstrom, J. D. (1974). Brain catechol synthesis: control by brain tyrosine concentration. Science, 185(4146), 183-184.
  8. Scally, M. C., Ulus, I., & Wurtman, R. J. (1977). Brain tyrosine level controls striatal dopamine synthesis Journal of neural transmission, 41(1), 1-6.9.
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  10. During, M. J., Acworth, I. N., & Wurtman, R. J. (1989). Dopamine release in striatum: physiological coupling to tyrosine supply. Journal of neurochemistry, 52(5), 1449-1454.
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  12. Yeghiayan, S. K., Luo, S., Shukitt-Hale, B., & Lieberman, H. R. (2001). Tyrosine improves behavioral and neurochemical deficits caused by cold exposure. Physiology & behavior, 72(3), 311-316.13
  13. Gibson, C. J., & Wurtman, R. J. (1978). Physiological control of brain norepinephrine synthesis by brain tyrosine concentration. Life Sciences, 22(16), 1399-1405.
  14. Colzato, L., Jongkees, B., Sellaro, R., & Hommel, B. (2013). Working memory reloaded: tyrosine repletes updating in the N-back task. Frontiers in behavioral neuroscience, 7, 200.
  15. Magill, R. A., Waters, W. F., Bray, G. A., Volaufova, J., Smith, S. R., Lieberman, H. R., … & Ryan, D. H. (2003). Effects of tyrosine, phentermine, caffeine D-amphetamine, and placebo on cognitive and motor performance deficits during sleep deprivation. Nutritional neuroscience, 6(4), 237-246.
  16. Deijen, J. B., & Orlebeke, J. F. (1994). Effect of tyrosine on cognitive function and blood pressure under stress. Brain research bulletin, 33(3), 319-323
  17. Mahoney, C. R., Castellani, J., Kramer, F. M., Young, A., & Lieberman, H. R. (2007). Tyrosine supplementation mitigates working memory decrements during cold exposure. Physiology & behavior, 92(4), 575-582.
  18. O’Brien, C., Mahoney, C., Tharion, W. J., Sils, I. V., & Castellani, J. W. (2007). Dietary tyrosine benefits cognitive and psychomotor performance during body cooling. Physiology & behavior, 90(2-3), 301-307.
  19. Shurtleff, D., Thomas, J. R., Schrot, J., Kowalski, K., & Harford, R. (1994). Tyrosine reverses a cold-induced working memory deficit in humans. Pharmacology Biochemistry and Behavior, 47(4), 935-941.
  20. J.R. Thomas, P.A. Lockwood, A. Singh, P.A. Deuster, Pharmacol. Biochem. Behav. 64 (1999) 495–500.
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  22. Prochazkova, L., Lippelt, D. P., Colzato, L. S., Kuchar, M., Sjoerds, Z., & Hommel, B. (2018). Exploring the effect of microdosing psychedelics on creativity in an open-label natural setting. Psychopharmacology, 235(12), 3401-3413.
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  24. Colzato, L. S., Jongkees, B. J., Sellaro, R., van den Wildenberg, W. P., & Hommel, B. (2014). Eating to stop: tyrosine supplementation enhances inhibitory control but not response execution. Neuropsychologia, 62, 398-402.
  25. Banderet, L. E., & Lieberman, H. R. (1989). Treatment with tyrosine, a neurotransmitter precursor, reduces environmental stress in humans. Brain research bulletin, 22(4), 759-762.
  26. Lehnert, H., Reinstein, D. K., Strowbridge, B. W., & Wurtman, R. J. (1984). Neurochemical and behavioral consequences of acute, uncontrollable stress: effects of dietary tyrosine. Brain research, 303(2), 215-223.
  27. Palinkas, L. A., Reedy, K. R., Smith, M., Anghel, M., Steel, G. D., Reeves, D., … & Reed, H. L. (2007). Psychoneuroendocrine effects of combined thyroxine and triiodothyronine versus tyrosine during prolonged Antarctic residence. International Journal of circumpolar health, 66(5), 402-417.



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