Although the exact causes of attention deficit hyperactivity disorder, or ADHD, haven't yet been determined, researchers theorize that it may be connected to brain levels of the neurotransmitter dopamine. L-tyrosine is the precursor compound to dopamine, and a number of scientific studies have focused on whether L-tyrosine supplementation is an effective treatment for people with ADHD. Although more studies and clinical trials are needed, L-tyrosine supplementation does not appear to alleviate ADHD symptoms. Consult your doctor before using L-tyrosine.
L-tyrosine is an amino acid that is synthesized within the body from phenylalanine, another amino acid. It is also found in high concentrations in poultry, soy products, dairy products, pumpkin seeds, sesame seeds, peanuts and lima beans. L-tyrosine has four main functions: it aids in the production of many of the body's proteins; skin cells use it to make melanin; it is needed for the proper function of glands in the endocrine system; and it is the base compound used in the production of essential neurotransmitters epinephrine, norepinephrine and dopamine. Researchers have studied L-tyrosine's ability to help with stress, memory retention, depression, fatigue and athletic performance, though no reliable evidence points to L-tyrosine being of any benefit.
Possible Function in ADHD
People with ADHD have one thing in common -- their brains appear to have less dopamine activity than those of people who do not have ADHD. Scientists are not certain whether this is because people with ADHD have lower than normal dopamine concentrations, fewer neural dopamine receptors or defective dopamine receptors. In the early 1980s, scientists hypothesized that the problems with dopamine in ADHD might be due to deficiencies in L-tyrosine.
The role L-tyrosine may play in ADHD was first researched in 1987. In a study published in the "American Journal of Psychiatry," scientists found that while many of the ADHD adults being supplemented with L-tyrosine seemed to experience decreased symptoms at first, by the end of the eight-week trial, there was no substantive change in the adults' behavior. Since that time, additional research studies have come to the same conclusion: supplementing with additional L-tyrosine does not appear to significantly improve the symptoms suffered by either adult or child ADHD patients.
The U.S. Food and Drug Administration does not regulate commercially produced L-tyrosine supplements; therefore, any L-tyrosine products you may purchase have not been checked for effectiveness, purity or safety. In addition, L-tyrosine supplementation may cause migraine headaches, nausea, heartburn and joint pain and may exacerbate the symptoms of Graves disease and hyperthyroidism. The supplements may also interfere with the function of medications like levodopa and monoamine oxidase inhibitors like selegiline, phenelzine and isocarboxazid. Do not use L-tyrosine without first speaking to your doctor about the possible side effects and dangers.
- VitaGuide.org: L-Tyrosine
- University of Maryland Medical Center: Tyrosine
- eMedTV: Tyrosine
- "The Journal of Clinical Psychiatry"; Effect of Tyrosine on Attention Deficit Disorder with Hyperactivity; J. Eisenberg, et al.; May 1988
- Neuroscience for Kids; ADHD Gets Some Attention (Attention Deficit Hyperactivity Disorder); Eric Chudler, Ph.D.