Overview:

Tyrosine is a nonessential amino acid the body makes from another amino acid called phenylalanine. It is a building block for several important neurotransmitters, including epinephrine, norepinephrine, serotonin, and dopamine. Neurotransmitters help nerve cells communicate and influence mood. Tyrosine also helps produce melanin (the pigment responsible for hair and skin color) and helps in the function of organs responsible for making and regulating hormones, including the adrenal, thyroid, and pituitary glands. It is involved in the structure of almost every protein in the body.

Tyrosine deficiencies are rare. Low levels have been associated with low blood pressure, low body temperature, and an underactive thyroid. This does not mean, however, that taking tyrosine supplements will improve any of these conditions.

Phenylketonuria (PKU)

This serious condition occurs in people who cannot metabolize the amino acid phenylalanine and leads to brain damage, including mental retardation. People with PKU must avoid any phenylalanine in their diets. Because tyrosine is made from phenylalanine, people with PKU can be deficient in tyrosine. Tyrosine is used in protein supplements for people with PKU, but most doctors don't recommend more tyrosine supplements. If you have PKU, your doctor will determine if you need more tyrosine and how much.

Stress

Tyrosine is involved in the production of the stress hormones epinephrine and norepinephrine. Some researchers believe that, under stress, the body isn't able to make enough tyrosine from phenylalanine. Some animal and human studies suggest that tyrosine supplements may help improve memory and performance under psychological stress, but more research is needed.

Sleep deprivation

One study suggests that taking tyrosine may help you be more alert after sleep deprivation, but more research is needed.

Other

Some athletes claim that tyrosine helps their performance. However, there is no proof that this claim is true or safe.

Because tyrosine helps the body produce the mood-influencing chemicals serotonin and dopamine, and because people who are depressed often have low levels of tyrosine, researchers have thought that tyrosine might help treat depression. However, studies have found that it has no effect.

Dietary Sources:

Tyrosine is found in soy products, chicken, turkey, fish, peanuts, almonds, avocados, bananas, milk, cheese, yogurt, cottage cheese, lima beans, pumpkin seeds, and sesame seeds.

Available Forms:

Tyrosine is also available as a dietary supplement, in capsule or tablet form.

How to Take It:

You should take tyrosine supplements at least 30 minutes before meals, divided into three daily doses. Taking vitamins B6, B9 (folate), and copper along with tyrosine helps the body convert tyrosine into important brain chemicals.

Pediatric

There is no specific dietary recommendation for tyrosine. Talk to your doctor before giving a child any dietary supplement.

Adult

Doses vary. Talk to your nutritionist or doctor about what dose is right for you. The dose most commonly recommended is 500 - 1,000 mg three times per day (before each of the three meals). To treat symptoms of sleep deprivation, 150 mg per kilogram of body weight, per day, has been used.

Precautions:

Because of the potential for side effects and interactions with medications, you should take dietary supplements only under the supervision of a knowledgeable health care provider.

People who have migraine headaches should avoid tyrosine, as it can trigger migraine headaches and gastrointestinal upset.

People with hyperthyroidism or Graves disease should avoid tyrosine supplements because tyrosine may increase levels of thyroid hormone.

Possible Interactions:

If you are currently being treated with any of the following medications, you should not use tyrosine supplements without first talking to your health care provider.

Monoamine Oxidase Inhibitors (MAOIs) -- Tyrosine may cause a severe increase in blood pressure in people taking the antidepressant medications known as MAOIs. This rapid increase in blood pressure (also called "hypertensive crisis") can lead to a heart attack or stroke. For this reason, people taking MAOIs should avoid foods and supplements containing tyrosine. MAOIs include:

• Isocarboxazid (Marplan)
• Phenelzine (Nardil)
• Tranylcypromine (Parnate)
• Selegiline

Thyroid hormone -- Tyrosine is a precursor to thyroid hormone, so it might raise levels too high when taken with synthetic thyroid hormones.

Levodopa(L-dopa) -- No one should take tyrosine at the same time as levodopa, a medication used to treat Parkinson's disease because levodopa may interfere with the absorption of tyrosine.

Alternative Names:

L-tyrosine