L-tyrosine, also called tyrosine, is is a non-essential amino acid that is important for certain body processes. Your body produces these types of amino acids naturally, and obtaining them through diet is not necessary. However,adding more L-tyrosine may have beneficial effects. L-tyrosine can be found in foods containing protein, such as meat, fish, dairy products, soy, nuts and avocados. Supplements also are available.
Neurotransmitter Production
L-tyrosine is necessary for the production of several neurotransmitters involved in helping nerve cells communicate and in regulating mood, according to the UMHS. These include dopamine, serotonin, epinephrine, norepinephrine and levadopa, also known as L-dopa. Imbalances in these neurotransmitters are associated with health conditions such as anxiety disorder, depression and Parkinson's disease. Epinephrine and norepinephrine are stress hormones produced by the adrenal gland, and research indicates that tyrosine supplements may help improve memory and performance when an individual experiences psychological stress, according to the University of Maryland Medical Center.
Sleep Deprivation Benefits
A study published in the August 2003 issue of "Nutritional Neuroscience" investigated the effects of L-tyrosine on cognitive and motor performance after sleep deprivation, a condition which impairs these functions. Participants--all healthy young men--took either 150 mg of tyrosine, a stimulant or a placebo following overnight sleep deprivation. Stimulants included 300 mg of caffeine, 37.5 mg of phentermine or 20 mg of D-amphetamine. All the active substances, including L-tyrosine, improved at least some aspects of cognitive and motor performance after sleep deprivation.
A study published in the April 1995 issue of "Aviation, Space and Environmental Medicine" examined the effects of 150 mg of tyrosine compared with placebo on participants during continuous nighttime work after one night's sleep loss. Tyrosine was associated with a significant improvement in the typical performance decline connected with sleep deprivation.
Side Effects
L-tyrosine generally is not associated with side effects, although it can cause digestive upset. People with certain health conditions should not take tyrosine supplements, according to the UMMC. L-tyrosine can induce migraine headaches, so people prone to migraines should not take this substance. Patients with overactive thyroid, known as hyperthyroidism, and those with Graves disease also should not take L-tyrosine because this amino acid may increase thyroid hormone levels. Individuals taking monoamine oxidase inhibitors, which are antidepressant medications called MAOIs, also should not take L-tyrosine because the combination can cause a severe increase in blood pressure. The safety of long-term L-tyrosine supplementation, particularly in doses over 1,000 mg daily, is unknown, according to the University of Michigan Health System, which recommends taking that amount only with a doctor's supervision.
References
- University of Michigan Health System: L-Tyrosine
- University of Maryland Medical Center: Tyrosine
- Nutritional Neuroscience: Effects Effects of Tyrosine on Cognitive and Motor Performance Deficits During Sleep Deprivation
- Aviation, Space and Environmental Medicine: Effects of Tyrosine on Cognitive Performance During Extended Wakefulness
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