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5 Benefits and Side Effects of Tyrosine (6 Contraindications To Be Noted)

Tyrosine is a common amino acid dietary supplement often used to improve alertness and concentration in stressful situations.

In empirical medicine, what are the benefits of tyrosine supplementation? Are there any side effects of tyrosine? See text analysis for details.

What is Tyrosine?

Tyrosine is a non-essential neutral amino acid or conditioned essential amino acid, because it can be synthesized from the essential amino acid phenylalanine, which is a precursor used by the body to make proteins, neurotransmitters and other important compounds, including: dopamine, epinephrine and norepinephrine, thyroid hormone, melanin synthesis are all related to it.

Tyrosine is found in many foods, especially protein-rich foods such as dairy products, meat, fish, eggs, seeds, nuts, and legumes, and the word “tyros” means “cheese” in Greek.

What are the proven benefits of tyrosine?

1. Tyrosine improves cognitive memory function (under stress)

Memory is the ability to retain information and recall it later, a basic biological function that is essential for survival. Short-term memory relies on the function of the frontal and parietal lobes, while long-term memory relies on the function of large areas of the brain.

There is substantial evidence that stress and increased glucocorticoid levels can have complex effects on memory performance, with both negative and positive effects.

Two controlled studies have shown that tyrosine supplementation is effective in improving memory decline caused by cold. Note 1 / Note 2

A double-blind, randomized, placebo-controlled study in which tyrosine supplementation helped improve cognitive flexibility in task-switching mode. Note 6

*Conclusion: Tyrosine supplementation may improve cognitive memory decline associated with stressful states, but in general, it is not helpful for mental improvement

2. Tyrosine is beneficial for phenylketonuria

Phenylketonuria is a birth defect in phenylalanine metabolism caused by phenylalanine hydroxylase deficiency, which leads to abnormal accumulation of phenylalanine and its metabolites in the patient’s tissues and body fluids.

Clinical features may include developmental delay, severe intellectual disability, autistic behavior, skin dyspigmentation, movement disorders, eczematous rash, and epilepsy. As we age, behavioral and mental disorders become apparent.

There is currently no cure for phenylketonuria, but the mainstream treatment is mainly phenylalanine-restricted diet, supplemented by specially designed medical foods.

In a Cochrane Database of Systematic Reviews (3 randomized controlled trials of 56 people with phenylketonuria), although tyrosine supplementation increased blood tyrosine levels, no significant differences were found between other measures (including: intelligence, neuropsychological performance, growth and nutritional status, mortality, and quality of life). Note 3

*Conclusion: Up to now, the use of tyrosine in patients with phenylketonuria has not been significantly helpful, and more studies need to further confirm in the future

3. Tyrosine is beneficial for depression

Depression is a mood disorder that manifests itself primarily as persistent sadness or loss of happiness, or both.

Its global annual prevalence is 5.5% in women and 3.2% in men, respectively, and the incidence is about 1.7 times higher in women.

The increased prevalence of depression in women may be associated with hormonal changes, especially during puberty, premenstruation, post-pregnancy, and perimenopause.

A randomized, double-blind controlled trial (in 65 patients with melancholic disorder who met diagnostic criteria) noted that oral tyrosine increased excretion of 3-methoxy-4-hydroxybenzenediol (MHPG) but had no antidepressant activity. Note 4

*Conclusion: For patients with depression, the use of tyrosine has not been associated with clinical improvement

4. Tyrosine is beneficial for schizophrenia

Schizophrenia, a brain disorder that affects a person’s behavior, thinking, and perception of the world, is characterized by delusions, hallucinations, inattention, lack of motivation, incoherence, and reduced emotional expression, affecting about 1% of the population.

According to statistics, the burden of long-term disability associated with schizophrenia is much greater than that of any other mental disorder, with direct costs of 1% to 3% of the national health care budget.

With both pharmacological and non-pharmacological treatments, many people with schizophrenia can live independently and achieve a normal standard of living.

One placebo-controlled, double-blind, cross-over trial noted that tyrosine plus drugs did not confer significant symptom improvement in schizophrenia compared with the drug morpholindone/molindone alone (as measured by weekly brief psychiatric rating scale (BPRS), negative symptom assessment schedule (SANS), or clinical overall impression (CGI) scale). Note 5

*Conclusion: Based on the current preliminary evidence, oral tyrosine has failed to improve schizophrenia

5. Tyrosine improves narcolepsy/narcolepsy

Narcolepsy is a type of sleep disorder characterized by typical daytime extreme sleepiness and irresistible sleep episodes, cataplexy (sudden bilateral loss of muscle tone), hallucinations and sleep paralysis before falling asleep, irregular sleep, involuntary behavior, poor concentration, memory loss, and blurred vision.

The prevalence of narcolepsy is about 0.05%, which has a great negative impact on the quality of life of patients, often coexisting with other sleep disorders, such as obstructive sleep apnea syndrome, periodic limb movements during sleep, and REM sleep behavior disorder) and nocturnal eating disorder.

A randomized, double-blind, placebo-controlled study (4 weeks, 10 people with narcolepsy) showed that tyrosine supplementation improved some visual analogue scoring measures, such as fatigue, drowsiness, and alertness, compared with placebo. Note 7

However, there were no significant differences in indicators such as daytime sleepiness, cataplexy, sleep paralysis, nocturnal sleep, overall clinical response, multiple sleep latency measurements, speed and attention tests.

*Conclusion: Tyrosine supplementation is not clinically significant in the treatment of narcolepsy.

Are there any side effects of tyrosine?

Tyrosine as a supplement is safe for use in short-term appropriate doses (up to 3 mg/kg daily oral dose) for most well-established populations.

However, possible side effects or adverse effects that have been reported include irritability, nausea, headache, fatigue, and heartburn.

Safety precautions (6 contraindications for use)

1. Patients with the hereditary disease tyrosinemia should use with caution, excessive amount may cause skin and eye lesions

2. Do not use by pregnant women, lactating women, and children (due to unknown safety)

3. Do not use for poor liver and kidney function (due to unknown safety)

4. Do not use it for patients taking thyroid supplementation drugs or hyperthyroidism, because additional tyrosine may increase thyroxine levels, resulting in excessive thyroxine, and even worsening symptoms

5. Do not use with Parkinson’s disease medications: levodopa may affect the efficacy of the drug

6. Do not combine with monoamine oxidase inhibitors, because the combination of monoamine oxidase inhibitors and high tyramine foods will increase blood pressure to dangerous levels.

Where can I buy the highest quality Tyrosine that is recommended by most people?

NOW Foods, L-Tyrosine, 500 mg, 120 Capsules

(Direct shipping from the United States / Worldwide delivery)

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Product Features:

Now Foods is one of several common national brands of health products in the United States, which has been established for more than 50 years.


The product line contains vitamins, minerals and herbal extracts, and has a high sales rate in major e-commerce channels.


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