NALT – An Overview
NALT (N-Acetyl L-Tyrosine) is a potent source of the amino acid l-tyrosine, which is a precursor to dopamine.
Supplementing with NALT can boost levels of dopamine in the brain, which could have a nootropic effect on the user.
Many people take NALT for:
- Stress Relief
NALT seems to be most effective at fighting the effects of fatigue and stress. People who are under difficult situations for an extended period of time usually get the most use out of this nootropic.1Jongkees BJ, et al. Effect of tyrosine supplementation on clinical and healthy populations under stress or cognitive demands–A review J Psychiatr Res. 2015
Some people also use NALT as a complementary treatment with ADHD medicine like Adderall and Ritalin. NALT can replenish the dopamine that these stimulants use up.
Some people even use NALT as a replacement for these drugs. 2Fernstrom JD, Fernstrom MH. Tyrosine, phenylalanine, and catecholamine synthesis and function in the brain J Nutr. 2007
What Does NALT Do?
NALT’s most powerful ability may be stress reduction, particularly during extreme situations.
Researchers have known for a while that tyrosine can make up for the neurotransmitters depleted during stressful situations.3Gibson CJ, Wurtman RJ. Physiological control of brain norepinephrine synthesis by brain tyrosine concentration Life Sci. 1978
Emotional stress has been shown to disbalance neurotransmitters like Dopamine and norepinephrine.
Post-traumatic stress can come from the depletion of these catecholamines. So, by replenishing these stocks, you could reverse the effects of this stress.4Antelman SM, Caggiula AR. Norepinephrine-dopamine interactions and behavior Science. 1977 5van der Kolk B, Greenberg M, Boyd H, Krystal J. Inescapable shock, neurotransmitters, and addiction to trauma: toward a psychobiology of post traumatic stress Biol Psychiatry. 1985
A significant number of human and animal studies back this up.
Researchers saw that NALT can increase mood, reaction time, and performance during periods of intense difficulty and stress.
This included fatigue from sleep deprivation and overexertion, hypothermia from work in cold temperature, and laboratory-induced stress.
In short, the researchers concluded that NALT could be useful for resisting the effects of working under extreme situations.
In fact, it seems that NALT’s benefits do not really kick in UNTIL you find yourself overstressed. It seems to act more for damage reduction than performance enhancement.6Harris R. Lieberman. Tyrosine and Stress: Human and Animal Studies Food Components to Enhance Performance: An Evaluation of Potential Performance-Enhancing Food Components for Operational Rations. 1994 7Brady K, Brown JW, Thurmond JB. Behavioral and neurochemical effects of dietary tyrosine in young and aged mice following cold-swim stress Pharmacol Biochem Behav. 1980 8Banderet LE, Lieberman HR. Treatment with tyrosine, a neurotransmitter precursor, reduces environmental stress in humans Brain Res Bull. 1989
NALT may also be able to reduce stress on the heart as well as the brain during trying times.9Pinto JM, Kirby DA, Lown B.. Epinephrine-induced decrease in repetitive extrasystole threshold is reversed by tyrosine in conscious dogs Life Sci. 1990
Because NALT works on dopamine, which is a major factor in mood, it may be useful as an antidepressant. Some users claim NALT is good for raising their mood.
However, clinical evidence is mixed.
A couple of rat studies found that NALT can replenish norepinephrine levels in rats. Low norepinephrine is associated with depression.
However, these effects were only noticeable in rats who were under stress.
This may point more to NALT being an anti-stress agent than an antidepressant.11Lehnert H, Reinstein DK, Strowbridge BW, Wurtman RJ. Neurochemical and behavioral consequences of acute, uncontrollable stress: effects of dietary tyrosine Brain Res. 1984 12Reinstein DK, Lehnert H, Scott NA, Wurtman RJ. Tyrosine prevents behavioral and neurochemical correlates of an acute stress in rats Life Sci. 1984
Theoretically, there are models of depression where low dopamine is the main factor.
Traditional antidepressants do not treat depression through this pathway.
This may be why some users claim that NALT has lifted them out of a depressed state.14Boadie W. Dunlop, MD; Charles B. Nemeroff, MD, PhD. The Role of Dopamine in the Pathophysiology of Depression Arch Gen Psychiatry. 2007
On the other hand, individuals with psychotic depression may have excess dopamine.
Therefore, adding more dopamine would probably worsen symptoms in this case.15Sapru MK, Rao BS, Channabasavanna SM.. Serum dopamine-beta-hydroxylase activity in clinical subtypes of depression Acta Psychiatr Scand. 1989
NALT seems to have a positive effect on memory. However, as mentioned above, it only seems to improve memory under stressful conditions.
So far, research has not shown that it can improve memory in otherwise normal situations.
Several studies looked at tyrosine and cold exposure. Exposure to low temperatures significantly degrades cognitive abilities in humans, especially memory.
It appears that by supplementing with tyrosine, participants were able to preserve their memory function versus those that did not.16Mahoney CR, Castellani J, Kramer FM, Young A, Lieberman HR.. Tyrosine supplementation mitigates working memory decrements during cold exposure Physiol Behav. 2007 17O’Brien C, Mahoney C, Tharion WJ, Sils IV, Castellani JW. Dietary tyrosine benefits cognitive and psychomotor performance during body cooling Physiol Behav. 2007 18Muller MD, et al. Acute cold exposure and cognitive function: evidence for sustained impairment Ergonomics. 2012
It can also improve working memory in people working at high elevation. High elevation can cause hypoxia induced neurodegeneration through lack of oxygen to the brain.
NALT can at least partially reverse that.19 Shukitt-Hale B, Stillman MJ, Lieberman HR. Tyrosine administration prevents hypoxia-induced decrements in learning and memory Physiol Behav. 1996
Tyrosine may sustain working memory when competing requirements to perform other tasks simultaneously degrade performance.
In other words, it helps with memory when multitasking.20Thomas JR, Lockwood PA, Singh A, Deuster PA. Tyrosine improves working memory in a multitasking environment Pharmacol Biochem Behav. 1999
Another trial with healthy young volunteers saw that NALT improved working memory, but only during elevated-stress conditions.21Lorenza S. Colzato, et al. Working Memory Reloaded: Tyrosine Repletes Updating in the N-Back Task Front Behav Neurosci. 2013
Current models of ADHD suggest that dopamine malfunction may be the cause of this disorder.
Pharmaceuticals like Adderall and Ritalin work by releasing more dopamine. These drugs are generally effective but do have some pretty nasty side effects.22Del Campo N, Chamberlain SR, Sahakian BJ, Robbins TW. The roles of dopamine and noradrenaline in the pathophysiology and treatment of attention-deficit/hyperactivity disorder Biol Psychiatry. 2011
So, some people have started supplementing with NALT to either replace their ADHD meds or to at least counteract the side effects caused by neurotransmitter depletion.
There are plenty of anecdotes that this is effective, although clinical evidence is mixed.
Some researchers believe that one risk factor for ADHD is trouble metabolizing catecholamines.
So, NALT could make up the deficit dopamine that your body has trouble making on its own.
One study of ADHD children found that NALT was effective at treating their symptoms. They claimed it might be as effective as traditional medication.24Marty Hinz, et al. Treatment of attention deficit hyperactivity disorder with monoamine amino acid precursors and organic cation transporter assay interpretation Neuropsychiatr Dis Treat. 2011
However, another (smaller) study failed to find any correlation between tyrosine and ADHD symptoms in children.25Eisenberg J, Asnis GM, van Praag HM, Vela RM. Effect of tyrosine on attention deficit disorder with hyperactivity J Clin Psychiatry. 1988
One study saw that NALT improved ADHD in patients that also had phenylketonuria. This makes sense, as phenylketonurics do not have the enzyme to convert phenylalanine into tyrosine.
This may cause a dopamine deficiency and be responsible for ADHD symptoms.
However, these results do not necessarily translate for non-phenylketonurics.26Posner J, Gorman D, Nagel BJ. Tyrosine supplements for ADHD symptoms with comorbid phenylketonuria J Neuropsychiatry Clin Neurosci. 2009
One interesting study indicates that tyrosine may be able to enhance inhibitory control in healthy students.
Inhibitory control is the ability to consciously stop automatic responses.
Researchers suspect that lack of inhibitory control is a hallmark of ADHD, leading to hyperactivity and not being able to focus attention.27Colzato LS, et al. Eating to stop: tyrosine supplementation enhances inhibitory control but not response execution Neuropsychologia. 2014
Cognitive and Mood Enhancement
There is some clinical evidence that NALT can raise mood and overall cognition.
Like it’s other effects, this seems to be the case mostly under stress and pressure.
Most of the studies saw at least some improvement on mental tasks vs placebo when participants took NALT.
Several trials also saw decreased blood pressure under stressful situations with NALT.28Deijen JB, Orlebeke JF. Effect of tyrosine on cognitive function and blood pressure under stress Brain Res Bull. 1994 29Steenbergen L, et al. Tyrosine promotes cognitive flexibility: evidence from proactive vs. reactive control during task switching performance Neuropsychologia. 2015 30Hase A, Jung SE, aan het Rot M. Behavioral and cognitive effects of tyrosine intake in healthy human adults Pharmacol Biochem Behav. 2015
However, there is also some evidence that tyrosine can cause anger in users who are subjected to stress.31Harris R. Lieberman, et al. The catecholamine neurotransmitter precursor tyrosine increases anger during exposure to severe psychological stress Psychopharmacology (Berl). 2015
How NALT Works In The Brain
When you take NALT, you are getting a highly bioavailable form of the non-essential acid l-tyrosine. Adding the acetyl group makes it easier for your body to absorb.
L-tyrosine is considered “non-essential” because your body can produce it on it’s own from the substance phenylalanine.
However, many people still do not get enough in their diets.32Harris R. Lieberman. Amino Acid and Protein Requirements: Cognitive Performance, Stress, and Brain Function The Role of Protein and Amino Acids in Sustaining and Enhancing Performance. 1999
Once it is absorbed by your body, the enzyme tyrosine hydroxylase converts it into the compound L-DOPA.
From L-DOPA, it rapidly converts to the neurotransmitter dopamine.
Dopamine is eventually broken down further into norepinephrine and, finally, epinephrine. 33NAGATSU T, LEVITT M, UDENFRIEND S. TYROSINE HYDROXYLASE. THE INITIAL STEP IN NOREPINEPHRINE BIOSYNTHESIS J Biol Chem. 1964 34Fernstrom JD, Faller DV. Neutral amino acids in the brain: changes in response to food ingestion J Neurochem. 1978
Dopamine, norepinephrine, and epinephrine are all crucial neurotransmitters that can have a huge impact on mood, focus, stress, and cognition.
So, by providing the raw materials for these transmitters, NALT can have a huge impact on the way your brain functions.
How Much NALT Should I Take?
Most people see a positive effect from NALT in the 200-500 mg range.
Some people see a better effect when they take it in the morning, others when they take it at night.
If you are stacking it with an ADHD medication, you may want to supplement with even more to counteract the dopamine depletion.
You may want to take as much as 2,000 mg, spaced throughout the day.
NALT Potential Side Effects
NALT is non-toxic and you cannot overdose on it. However, there are still some negative reactions with some people.
The most common side effects of NALT are :
- Anxiety and irritability
- Gastrointestinal issues
You should NOT take NALT if you are on MAOIs, have low blood pressure, or have certain thyroid problems.
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