L-tyrosine is a chemical building block known as an amino acid. The "L" in the name refers to the left-handed configuration of the molecule. L-tyrosine plays an important role in the production of hormones, melanin and neurotransmitters. As an amino acid, it is also part of the molecular foundation of all proteins. Because of its effect on brain function, researchers have tried to use L-tyrosine as part of treatment for attention deficit disorder, with varied results.
Dietary Sources
L-tyrosine is a nonessential amino acid. This means your body produces L-tyrosine independent of its consumption. Components necessary for production of L-tyrosine come from another amino acid known as phenylalanine. This amino acid is found in beef, poultry, pork, fish, milk, yogurt, eggs, cheese and soy products. Health companies also sell L-tyrosine as a dietary supplement. However, deficiencies of L-tyrosine are rare, and its medical applications are limited.
ADHD
Approximately 8 to 9 million adults, or 4 percent to 6 percent of the U.S. population, have attention deficit hyperactivity disorder. It is not a condition limited to children. People with ADHD tend to be distractible, impulsive and hyperactive. For an ADHD diagnosis, these symptoms must be excessive and long-lasting; they must appear before age 7 and create difficulties for the person. Other symptomatic behaviors include difficulty following instructions, difficulty awaiting turns, excessive talking and failure to listen when spoken to directly.
Neurotransmitters
L-tyrosine is a building block for several important neurotransmitters, including epinephrine, norepinephrine and dopamine. Neurotransmitters are like chemical messengers that influence mood and help nerve cells communicate. Researchers think ADHD arises from various genetic or environmental factors, many of which depress neurotransmitters such as dopamine. The provenance of the condition is complex, and the degree to which ADHD can be treated after its onset is not entirely known.
Research
Most research involving the effects of L-tyrosine upon ADHD comes from the 1980s. A 1987 study published in "The American Journal of Psychiatry" found that eight of the subjects participating in the trial demonstrated moderate clinical responses to L-tyrosine, but developed a tolerance to the treatment after only six weeks. A year later, another study found that none of the subjects in the trial showed a significant improvement with a treatment using L-tyrosine. However, more recent research from 2011 has suggested that a novel amino acid protocol specifically designed to increase the total number of neurotransmitters in the central nervous system achieved significant improvements in two thirds of participants tested. L-tyrosine was a major part of the amino acid mixture. However, further testing is needed to verify the results.
References
- University of Maryland Medical Center; Tyrosine; Steven D. Ehrlich, et al.; July 2010
- Attention Deficit Disorder Association; ADHD Fact Sheet; Peter Jaksa; 1998
- Science Daily; ADHD Appears To Be Associated With Depressed Dopamine Activity In The Brain; August 2007
- "The American Journal of Psychiatry"; An Open Trial of L-Tyrosine in the Treatment of Attention Deficit Disorder, Residual Type; F.W. Reimherr, et al.; August 1987
- "The Journal of Clinical Psychiatry"; Effect of Tyrosine on Attention Deficit Disorder with Hyperactivity; J. Eisenberg, et al.; May 1988
- "Neuropsychiatric Disease and Treatment"; Treatment of Attention Deficit Hyperactivity Disorder with Monoamine Amino Acid Precursors and Organic Cation Transporter Assay Interpretation; Marty Hinz, et al.; January 2011
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