L-tyrosine, a nonessential amino acid made by the body, helps produce melanin and serves as a building block for some mood-altering neurotransmitters. Sources of L-tyrosine include supplements, meats, eggs, beans, oats, wheat, nuts and fish. This amino acid may help treat phenylketonuria, improve brain functioning during times of stress and increase alertness during sleep deprivation, according to the University of Maryland Medical Center. As with any drug or supplement, consult your doctor before using L-tyrosine.
Mild Side Effects
The most common side effects reported for L-tyrosine include headaches, nausea, fatigue, joint pain and heartburn. "All medications often cause these commonly reported side effects," according to Barbara Mendez, a registered pharmacist and nutritional consultant in New York City. Mendez continues by stating that the studies done on L-tyrosine are rather small in size, so there could be more side effects than this and these side effects could have a different cause.
Thyroid Function
Do not take L-tyrosine if you suffer from any form of overactive thyroid, or hyperthyroidism, such as Graves disease. L-tyrosine helps create thyroxine, a type of thyroid hormone, which aggravates all types of hyperthyroidism when too high within the body. People with hypothyroidism who take synthetic thyroid hormones should also avoid taking L-tyrosine, because this combination can also elevate thyroxine levels too far.
Pregnancy and Breast-Feeding
Current scientific studies have not provided enough information on the use of L-tyrosine during pregnancy or breast-feeding, warns Dr. Abaz Sosic, an obstetrician for Bradford Regional Medical Center, in Bradford, Pennsylvania. He advises not using L-tyrosine supplements during these times. However, consuming moderate amounts of this amino acid from food sources should have no impact on you or your baby, because food sources do not provide you with a concentrated dose like the supplements do.
MAOIs
People on monoamine oxidase inhibitors, often called MAOIs, should avoid taking L-tyrosine supplements or eating foods containing L-tyrosine because the combination of the two can cause severe spikes in blood pressure. Since the body cannot adapt quick enough to rapid increases in blood pressure, this may lead to a stroke or a heart attack. Common MAOIs include isocarboxazid, phenelzine, tranylcypromine and selegiline. While most people take newer antidepressants that have fewer side effects, doctors still prescribe MAOIs to patients that do not respond to the newer medications. Talk to your doctor about possible interactions if you take any type of medication.
Levadopa
Levadopa, a common medication used to treat Parkinson's disease might decrease the amount of L-tyrosine your body absorbs, and vice versa, according to Mendez. By taking levadopa with L-tyrosine, you may decrease the effectiveness of both substances.
References
- University of Maryland Medical Center; Tyrosine; July 2010
- Barbara M. Mendez, RPh, MS; Private Practice; New York, New York
- Anaz Sosic, M.D.; Bradford Regional Medical Center; Bradford, Pennsylvania
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